ANTS UNCOVERING THE TRUTH
ANTS DEPARTMENT OF THE ARMY
ANTS UNCOVERING THE TRUTH
Copyright © 2015 by Gino Santoro All rights reserved. No part of this publication may be reproduced, distributed, or transmitted in any form or by any means, including photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the publisher, except in the case of brief quotations embodied in critical reviews and certain other noncommercial uses permitted by copyright law. For permission requests, write to the publisher, addressed “Attention: Permissions Coordinator,” at the address below. Printed in the United States of America
This book is dedicated to the ants. Researching this topic has given me a new found respect for them.
CONTENTS
WARNING
This book is the property of the United States Government. It is unlawful to sell it to any other person, or to use it or permit anyone else to use it, except to obtain rationed goods in accordance with regulations of the Office of Price Administration.
06 Ants
Fa c t s
14
22
39
Communi-
of
Architects
cation
Labor
Ants
Division
Master
No. 01
Major General Karl W. Gustafson The Provost Marshal General Department of the Army Washington, D.C. 20314
Dear General Gustafson:
Ants, the most common household pest, can be a mere nuisance or more than that: there are some that just want to share the food, but others sting or damage building materials. In the same family with bees and wasps, the ant is a member of a group of insects with thousands of species, some of which are household pests. They can range in size from 0.1� (.25 cm) to 1� (2.54 cm), and are variously yellow, red, brown, black, or a blend. Being omnivorous, they eat human food as well as waste. In addition, the carpenter ant creates living area in wood, often choosing sites where the wood is wet and damaged. Ants have a clearly delineated 3-section body (head, thorax, and abdomen), six legs, compound eyes, and a pair of antennae. Some have stings, and some can spray poison. Some varieties have wings. They are nocturnal, being most active at night. Since ants like to parade in line, it may be fairly easy to find the point of entry that they are using. When found, seal it. Sincerely yours,
JEREMIAH P. HOLLAND Brigadier General U.S. Army
ANT FACTS Any further letter on this subject should be addressed to: Office i/c
FRANCIS J. HARVEY, Records,
and the following No. quoted
026849
Forms/B104-125/2 Wt30243.1252
500M
9/39
K.H.k> 1179
01
Serial.
N o 920315
UNITED STATES DEPARTMENT OF AGRICULTURE For use of secretariat.
Date of Receipt in Secretariat.
Registered Number.
P.262/US/j/225 Name of Species.
1. Formicidae
Description.
1. 2. 3. 4. 5.
2 1 feb 1952
Large head Slender Oval abdomen joined to the thorax small waist Six legs
SHORT STATEMENT OF FACTS
Ant are from the Formicidae family that are social in habit and live together in organized colonies. Ants occur worldwide but are especially common in hot climates. They range in size from about 2 to 25 mm (about 0.08 to 1 inch). Their colour is usually yellow, brown, red, or black. A few genera (e.g., Pheidole of North America) have a metallic lustre. Typically, an ant has a large head and a slender, oval abdomen joined to thethorax, or midsection, by a small waist. In all ants there are either one or two finlike extensions running across the thin waist region. The antennae are always elbowed. There are two sets of jaws: the outer pair is used for carrying objects such as food and for digging, and the inner pair is used for chewing. Some species have a powerful sting at the tip of the abdomen. Like all insects, ants have six legs. Each leg has three joints. The legs of the ant are very strong so they can run very quickly. If a man could run as fast for his size as an ant can, he could run as fast as a racehorse. Ants can lift 20 times their own body weight. An ant brain has about 250 000 brain cells. A human brain has 10,000 million so a colony of 40,000 ants has collectively the same size brain as a human. The average life expectancy of an ant is 45-60 days. Ants use their antenae not only for touch, but also for their sense of smell. The head of the ant has a pair of large, strong jaws. The jaws open and shut sideways like a pair of scissors. Adult ants cannot chew and swallow solid food. Instead they swallow the juice which they squeeze from pieces of food. They throw away the dry part that is left over. The ant has two eyes, each eye is made of many smaller eyes. They are called compound eyes. The abdomen of the ant contains two stomachs. One stomach holds the food for itself and second stomach is for food to be shared with other ants. Like all insects, the outside of their body is covered with a hard armour this is called the exoskeleton. Ants have four distinct growing stages, the egg, larva, pupa and the adult. Biologists classify ants as a special group of wasps. (Hymenoptera Formicidae) There are over 10000 known species of ants. Each ant colony has at least one or more queens.
No. 05
A N T S D E C L A S S I F I E D | Ant Facts
Head Mesosoma Gaster
Forms/B104-125/2 Wt30243.1252 1179
500M
9/39
K.H.k>
[14]
[13]
[12]
[00]
[02] [01]
[03] [04]
No. 07
A N T S D E C L A S S I F I E D | Ant Facts
Forms/B104-125/2 Wt30243.1252
500M
9/39
K.H.k>
1179
ANATOMY
[11]
[10]
[09]
[00]
Pygidium
[01]
Femur
[02]
Tibia
[03]
Trochanter
[04]
Coxa
[05]
Tarsal Claw
[06]
Funiculi
[07]
Mandible
[08]
Antennae
[09]
Eye
[10]
Protonum
[11]
Mesonotum
[12]
Peduncle
[13]
Petiole
[14]
Wing
The queen begins her life with wings, which she uses while mating.
After mating with a male ant (or many males), she flies to her nesting area.
She then loses her wings and spends her life laying eggs.
[08]
[07]
[06]
[05]
Any further letter on this subject should be addressed to: Office i/c
John harvey
, Serial.
No
Records,
ant the following No. quoted
920315 FACTS CONTINUED
The job of the queen is to lay eggs which the worker ants look after. Worker ants are sterile, they look for food, look after the young, and defend the nest from unwanted visitors. Ants are clean and tidy insects. Some worker ants are given the job of taking the rubbish from the nest and putting it outside in a special rubbish dump! Each colony of ants has its own smell. In this way, intruders can be recognized immediately. Many ants such as the common Red species have a sting which they use to defend their nest. The common Black Ants and Wood Ants have no sting, but they can squirt a spray of formic acid. Some birds put ants in their feathers because the ants squirt formic acid which gets rid of the parasites. The Slave-Maker Ant (Polyergus Rufescens) raids the nests of other ants and steals their pupae. When these new ants hatch,they work as slaves within the colony. The worker ants keep the eggs and larvae in different groups according to ages. At night the worker ants move the eggs and larvae deep into the nest to protect them from the cold. During the daytime, the worker ants move the eggs and larvae of the colony to the top of the nest so that they can be warmer. If a worker ant has found a good source for food, it leaves a trail of scent so that the other ants in the colony can find the food. Army Ants are nomadic and they are always moving. They carry their larvae and their eggs with them in a long column. The Army Ant (Ecitron Burchelli) of South America, can have as many as 700,000 members in its colony. The Leaf Cutter Ants are farmers. They cut out pieces of leaves which they take back to their nests. They chew them into a pulp and a special fungus grows it. Ants cannot digest leaves because they cannot digest cellulose. Many people think ants are a pest but I like them. To stop them coming into my kitchen I put some sugar outside. They they have so much to eat that they are not interested in coming into my kitchen. There are generally three castes, or classes, within a colony: queens, males, and workers. Some species live in the nests of other species as parasites. In these species the parasite larvae are given food and nourishment by the host workers. Wheeleriella santschii is a parasite in the nests of Monomorium salomonis, the most common ant of northern Africa. Most ants live in nests, which may be located in the ground or under a rock or built above ground and made of twigs, sand, or gravel. Carpenter ants (Camponotus) are large black ants common in North America that live in old logs and timbers. Some species live in trees or in the hollow stems of weeds. Tailor, or weaver, ants, found in the tropics of Africa (e.g., Tetramorium), make nests of leaves and similar materials held together with silk secreted by the larvae.Dolichoderus, a genus of ants that are found worldwide, glues together bits ofanimal feces for its nest. The widely distributed pharaoh ant (Monomarium pharaonis), a small yellowish insect, builds its nest either in houses, when found in cool climates, or outdoors, when it occurs in warm climates. Army ants, of the subfamily Dorylinae, are nomadic and notorious for the destruction of plant and animal life in their path. The army ants of tropical America (Eciton), for example, travel in columns, eating insects and other invertebrates along the way. Periodically, the colony rests for several days while the queen lays her eggs. As the colony travels, the growing larvae are carried along by the workers. Habits of the African driver ant (Dorylus) are similar. The red imported fire ant (Solenopsis invicta), introduced into Alabama from South America, had spread throughout the southern United States by the mid-1970s. It inflicts a painful sting and is considered a pest because of the large soilmounds associated with its nests. In some areas the red imported fire ant has been displaced by the invasive tawny crazy ant (also called hairy crazy ant, Nylanderia fulva), a species known in South America that was first detected in the United States (in Texas) in 2002. The hairy crazy ant is extremely difficult to control and is considered to be a major pest and threat to native species and ecosystems.
No. 09
A N T S D E C L A S S I F I E D | Ant Facts
The life cycle of the ant has four stages, including egg, larva, pupa, and adult, and spans a period of 8 to 10 weeks. The queen spends her life laying eggs. The workers are females and do the work of the colony, with larger individuals functioning as soldiers who defend the colony. At certain times of the year, many species produce winged males and queens that fly into the air, where they mate. The male dies soon afterward, and the fertilized queen establishes a new nest. The food of ants consists of both plant and animal substances. Certain species, includ ing those of the genus Formica, often eat the eggs and larvae of other ants or those of their own species. Some species eat the liquid secretions of plants. The honey ants (Camponotinae, Dolichoderinae) eat honeydew, a by-product of digestion secreted by certain aphids. The ant usually obtains the liquid by gently stroking the aphid’s abdomen with its antennae. Some genera (Leptothorax) eat the honeydew that has fallen onto the surface of a leaf. The so-called Argentine ant (Iridomyrmex humilis) and the fire ant also eat honeydew. Harvester ants (Messor, Pogonomyrmex) store grass, seeds, or berries in the nest, whereas ants of the genus Trachymyrmex of South America eat only fungi, which they cultivate in their nests. The Texas leafcutter ant (Atta texana) is a pest that often strips the leaves from plants to provide nourishment for its fungus gardens. The social behaviour of the ants, along with that of the honeybees, is the most complex in the insect world. Slave-making ants, of which there are many species, have a variety of methods for “enslaving” the ants of other species. The queen ofBothriomyrmex decapitans of Africa, for example, allows herself to be dragged byTapinoma ants into their nest. She then bites off the head of the Tapinoma queen and begins laying her own eggs, which are cared for by the “enslaved” Tapinomaworkers. Workers of the slave-making ant Protomognathus americanus raid nests of Temnothorax ants, stealing the latter’s pupae. The pupae are raised by P. americanus to serve as slaves, and, because the Temnothorax pupae become imprinted on the chemical odour of the slave-making ants, the captive ants forageand routinely return to the slave-making ant nest.
Linepithema humile – Argentine ant
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Serial.
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No. 13
A N T S D E C L A S S I F I E D | Ant C odes
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For use of secretariat.
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UNITED STATES DEPARTMENT OF AGRICULTURE
P.263/US/j/215 s
4AP U HV
Name of Species.
1. Formicidae
Communicatio type.
1. Touching antennaes 2. Pheromone trails 3. Clicking sound from mandibles
2 2 feb 1952
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Date of Receipt in Secretariat.
Registered Number.
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FORAGING COMMUNICATION 8
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Social insects have several advantages over solitary insects. The presence of many individuals can increase system reliability, and work can also be organized more efficiently through division of labor and task partitioning. Another advantage is the possibility of sharing information, especially communicating where food can be found. But research is increasingly showing that foraging communication does more than merely direct nest mates to food. It also allows the colony to regulate total foraging activity, to retain a memory of previously rewarding locations, and to select among locations of different profitability. In this primer, we first provide a brief historical perspective, then focus on recent research that has uncovered remarkable richness and sophistication in ant foraging communication, and finally identify some key questions for further research.
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The study of foraging communication in social insects has a long history. In the 1880s the eminent Victorian John Lubbock (Baron Avebury) showed that ants used odor trails in foraging. His contemporary Wassmann even believed that ants had a sophisticated language encoded by antennal tapping, somewhat like Morse code. Far-fetched as Wassmann’s idea may seem, the subsequent discovery by Karl von Frisch that honeybee foragers use waggle dances to communicate both direction and distance of food sources showed sophistication in communication that seemed barely credible for an animal, let alone an insect. Von Frisch went on to win the 1973 Nobel Prize for physiology or medicine for this discovery. Research into chemical communication developed rapidly in the 1960s following the identification of the first two pheromones: queen substance in the honeybee and the male attractant of female silk moths. Investigation of numerous ant species demonstrated that a wide range of chemicals are used to mark pheromone trails and are produced by several different glands. Research published by E.O. Wilson in 1962 demonstrated that ant pheromone trails provide positive and negative feedback to organize foraging at the colony level. A colony forms a trail when successful foragers deposit pheromone on their return to the nest, with the trail gaining in strength as more and more workers add pheromone to it, so providing positive feedback. The trail decays when the food runs out because foragers refrain from reinforcing it on their return and the existing pheromone evaporates, so providing negative feedback.
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MULTI-PHEROMONE TRAILS
In the 1980s the new field of self-organization adopted ant pheromone trails as a paradigm to illustrate emergent processes, where the activities of many ‘agents’ responding only to local information leads to a global adaptive process. Mathematical and computational models showed how worker ants, which were credited with minimal individual intelligence, could work together to solve problems such as selecting the shorter of two paths between food and nest, or selecting the better food source when presented with two of differing quality. These models showed that adaptive global solutions could arise in a system with a single trail pheromone providing positive feedback. From a biological perspective, however, this may have oversimplified things. Most trail-using ants employ multiple trail pheromones secreted from one or more glands. But why use many pheromones if one is apparently sufficient? Recent research into the roles of multiple pheromones has uncovered remarkable sophistication of communication in ant foraging trail networks. In Pharaoh’s ants, for example, a suite of trail pheromones complement each other by providing a long-term memory of previously used trails, short-term attraction to currently rewarding trails, and a ‘no entry’ signal to unrewarding branches. The geometry of the trail system also provides information, and there is worker specialization in trail laying and detection. Natural selection will favor communication if it helps nest mates to forage more efficiently. In social insects, workers collect the food for the colony. So if worker A helps worker B to collect more food, this is as good to worker A as if she collected it herself, because the food is brought back to the same nest to feed the same larvae. Nevertheless, many species of social insects do not share foraging information. In some cases this may be because foragers have no useful information to share. For example, desert ants (Cataglyphis spp.) collect dead insects, but there would be little point in directing nest-mates to the site of a discovery if no food remains. Communication is most useful when food resources are found that are larger than can be exploited by a single forager, or that need defending. Large or renewable feeding sites would be well worth communicating to nest-mates, such as the location of a group of aphids secreting honeydew or a patch of flowers. In a general sense, social insect colonies live in a dynamic, competitive environment in which food sources of variable quality are constantly changing in location. Most ant species are dependent upon ephemeral food finds. In such an environment, there is an advantage to sharing information if it can help the colony direct its workers quickly to the best food sources. Persistent or recurring food sources may also be available, such as the aphids or scale insects ‘farmed’ by many ant species. The best strategy is often to remember rewarding foraging sites but also to be flexible enough to exploit newly discovered food and to select the better sources from those available. To this end, information directing nest mates to food also enables them to select the highest quality food find when multiple resources are available. Different ant species employ a range of communication methods for directing nest mates to foraging sites. The simplest is ‘tandem running’, where a successful forager leads a recruit. Recruitment is faster when the successful forager leads a group of recruits. The recruit or recruits follow the leader by physical contact or pheromone from the leader. The most spectacular use of trail pheromones is in mass foraging. Here the recruitment and guiding aspects of foraging communication are usually decoupled. The pheromone trail provides only the route to food, whilst recruitment of additional foragers is caused by other behaviors, such as dances or direct physical contact in the nest. In honeybees, the waggle dance recruits additional foragers but also directs them to the food. However, honeybees have another dance, the vibratory signal, which helps recruit more foragers but does not guide them to food. Decoupling means that mass foraging ants broadcast guidance information widely, potentially to all foragers, in the form of a trail network marked with varying amounts and types of pheromone. In contrast, the broadcast range of the honeybee waggle dance is limited to workers in contact with the dancer.
A N T S D E C L A S S I F I E D | Ant C odes
Ant pheromone trails contain many chemicals that differ greatly in their persistence. Trail pheromones are also secreted from a diverse range of glandular sources, such as the Dufour’s gland, poison gland, anal glands, glands on the feet, and glands on the thorax or abdomen. The use of multiple trail pheromones by a single ant species means that foraging communication can be more complex than is possible with a single pheromone. Many foraging insects, for example a worker honeybee, can individually remember where they have foraged and can return to rewarding sites. However, for trail-following ants this memory need not be an individual memory encoded in the brain. Instead, it can be a group memory encoded externally in the pheromone trail system. The use of several trail pheromones that differ in their persistence provides memory over differing time scales. In particular, a non-volatile pheromone can provide a longer-term memory, while a volatile pheromone can allow rapid choice among potential feeding locations by quickly ‘forgetting’ depleted locations. The traditional view of ant pheromone trails as short-lived signals designed for rapid effect is often illustrated by the swarm raids of army ants. Raiding army ants certainly use short-lived trails to coordinate their lightning raids. But recent research has detected a more complex array of pheromone signals. For example, in the Malaysian ponerine army ant, Leptogenys distinguenda ( Figure 1), distinct roles have been assigned to trail pheromones from two glands (poison and pygidial). Temporal and spatial variation in the use of three trail pheromones communicates context-specific information in directing and organizing raids. The poison gland of L. distinguenda contains two pheromone components. One elicits a strong short-term attraction to prey items. The other guides workers from foraging sites to the colony, but only weakly. The prey-attraction component directs more ants to prey encountered during raiding to ensure that the prey is swiftly overwhelmed. The number of foragers attracted is a non-linear function of pheromone concentration, such that a trail laid by just a few ants leads to a rapid increase in workers attacking the prey. In this way a small number of workers encountering prey can rapidly attract enough nestmates to capture the prey. This prey-attraction pheromone is highly volatile and lasts only 5 minutes, ensuring that ants are not attracted long after the prey item has been captured. In contrast, the pygidial gland of L. distinguenda produces a longer-lasting trail pheromone (approximately 25 minutes). When attacking prey, workers often become detached from the trail network and this pheromone guides them back to the trail, or the colony. The pygidial gland is responsible for maintaining the spatial organisation of raiding ants, helping them explore the environment for prey in a systematic manner. Raiding parties advance in a single direction on the trail, only departing when locating prey or when signalled to do so by the poison gland pheromone. Thus, the longer-lived trail pheromone forms a well-connected network from which all raiding excursions are made. The trail network ensures rapid and reliable communication between foragers and enables the rapid transport of prey items back to the colony.
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DIVISION OF LABOR Any further letter on this subject should be addressed to: Office i/c
FRANCIS J. HARVEY, Records,
and the following No. quoted
026849
Wt30243.1252 1179
500M
9/39
K.H.k>
Serial.
Forms/B104-125/2
N 920315
03
DEPARTMENT OF AGRICULTURE For use of secretariat.
Date of Receipt in Secretariat.
Registered Number.
P.263/US/j/215 Name of Species.
1. Formicidae
Communicatio type.
1. Touching antennaes 2. Pheromone trails 3. Clicking sound from mandibles
2 2 feb 1952
GENETICS DETERMINE DIVISION OF LABOR There are generally three castes, or classes, within a colony: queens, males, and workers. Some species live in the nests of other species as parasites. In these species the parasite larvae are given food and nourishment by the host workers. Wheeleriella santschii is a parasite in the nests of Monomorium salomonis, the most common ant of northern Africa. Most ants live in nests, which may be located in the ground or under a rock or built above ground and made of twigs, sand, or gravel. Carpenter ants (Camponotus) are large black ants common in North America that live in old logs and timbers. Some species live in trees or in the hollow stems of weeds. Tailor, or weaver, ants, found in the tropics of Africa (e.g., Tetramorium), make nests of leaves and similar materials held together with silk secreted by the larvae. Dolichoderus, a genus of ants that are found worldwide, glues together bits of animal feces for its nest. The widely distributed pharaoh ant (Monomarium pharaonis), a small yellowish insect, builds its nest either in houses, when found in cool climates, or outdoors, when it occurs in warm climates. Army ants, of the subfamily Dorylinae, are nomadic and notorious for the destruction of plant and animal life in their path. The army ants of tropical America (Eciton), for example, travel in columns, eating insects and other invertebrates along the way. Periodically, the colony rests for several days while the queen lays her eggs. As the colony travels, the growing larvae are carried along by the workers. Habits of the African driver ant (Dorylus) are similar. The red imported fire ant (Solenopsis invicta), introduced into Alabama from South America, had spread throughout the southern United States by the mid-1970s. It inflicts a painful sting and is considered a pest because of the large soil mounds associated with its nests. In some areas the red imported fire ant has been displaced by the invasive tawny crazy ant (also called hairy crazy ant, Nylanderia fulva), a species known in South America that was first detected in the United States (in Texas) in 2002. The hairy crazy ant is extremely difficult to control and is considered to be a major pest and threat to native species and ecosystems. The life cycle of the ant has four stages, including egg, larva, pupa, and adult, and spans a period of 8 to 10 weeks. The queen spends her life laying eggs. The workers are females and do the work of the colony, with larger individuals functioning as soldiers who defend the colony. At certain times of the year, many species produce winged males and queens that fly into the air, where they mate. The male dies soon afterward, and the fertilized queen establishes a new nest.
No. 23
A N T S D E C L A S S I F I E D | Division of Labor
1. Queen
2. Male
3. Worker
4. Soldier
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NATURE OF WORK
The food of ants consists of both plant and animal substances. Certain species, including those of the genus Formica, often eat the eggs and larvae of other ants or those of their own species. Some species eat the liquid secretions of plants. The honey ants (Camponotinae, Dolichoderinae) eat honeydew, a by-product of digestion secreted by certain aphids. The ant usually obtains the liquid by gently stroking the aphid’s abdomen with its antennae. Some genera (Leptothorax) eat the honeydew that has fallen onto the surface of a leaf. The so-called Argentine ant (Iridomyrmex humilis) and the fire ant also eat honeydew. Harvester ants (Messor, Pogonomyrmex) store grass, seeds, or berries in the nest, whereas ants of the genus Trachymyrmex of South America eat only fungi, which they cultivate in their nests. The Texas leafcutter ant (Atta texana) is a pest that often strips the leaves from plants to provide nourishment for its fungus gardens. The social behaviour of the ants, along with that of the honeybees, is the most complex in the insect world. Slave-making ants, of which there are many species, have a variety of methods for “enslaving” the ants of other species. The queen of Bothriomyrmex decapitans of Africa, for example, allows herself to be dragged by Tapinoma ants into their nest. She then bites off the head of the Tapinoma queen and begins laying her own eggs, which are cared for by the “enslaved” Tapinoma workers. Workers of the slave-making ant Protomognathus americanus raid nests of Temnothorax ants, stealing the latter’s pupae. The pupae are raised by P. americanus to serve as slaves, and, because the Temnothorax pupae become imprinted on the chemical odour of the slave-making ants, the captive ants forage and routinely return to the slave-making ant nest.
No. 25
A N T S D E C L A S S I F I E D | Division of Labor
Queen Nurse the brood Forage for food Defend their colony Reproduce
Male
Worker
Soldier
Forms/B104-125/2 Wt30243.1252
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MASTER ARCHITECTS Any further letter on this subject should be addressed to: Office i/c
FRANCIS J. HARVEY, Records,
and the following No. quoted
026849
Serial.
N 920315
04
ANTS ARE THE BEST DESIGNERS For use of secretariat.
Date of Receipt in Secretariat.
Registered Number.
P.263/US/j/215 Name of Species.
1. Formicidae
Diet.
1. Omnivore
Group name.
1. Army or Colony
2 2 feb 1952
To study the architecture of ant colonies and their nests, entomologist and myrmecologist Walter Tschinkel developed a way to “record” their three-dimensional underground chambers: he pours 1200F molten aluminum into the hill and then excavates the hardened cast. The entire process can take around seven hours. From the tunnel depths, patterns, variations, the “room” arrangements, and more, these resulting casts are full of information about different ant colonies and their behavior: “You can see that where there’s a lot of traffic near the surface, the shaft is actually a ribbon, a wide tunnel like a superhighway,” he says, gesturing to and describing the incredibly intricate ant architecture. “The more traffic it has, the wider it is.” And beyond that, the sculptures mix science with art. But, of course, there’s a cost of insect life in this process: “I don’t do it lightly, actually… The technique has helped prove that colonies can thrive up to 3.6 metres deep and house between 9,000 and 10,000 workers.”
A N T S D E C L A S S I F I E D | Master Architects
No. 29
A N T S D E C L A S S I F I E D | Master Architects
ALUMINUM CASTE
Humans often use poisons to get rid of these ants to protect their home and property, but one artist is using something different: molten aluminum. The aluminum is carefully poured into the top of the ant hill, and the metal goes throughout all of the tunnels and settles into all of the crevices. Once the aluminum has cooled and the dirt has been washed away, the cast makes a perfect representation of the nest’s internal structure.
No. 31
THE WORLD OF WALTER TSCHINKEL This is perfect soil for this kind of work,” says Walter Tschinkel, as sweat runs down his face. “You can dig a six-foot hole in an hour here.” His voice is muffled because that’s just what he has done—and then some. He’s crouched in the bottom of an eightfoot-deep hole in the ground, in a hot, dry, open field between the Tallahassee, Florida, airport and a sewage-treatment plant. Clay-infused sand comes flying out of the hole as he shovels. Tschinkel, 62, rests a moment, then picks up a trowel and pokes sand away from one wall of the pit. He glances up. “I think we can start taking it out,” he says. As he prods with the trowel tip, a fantastic sculpture begins to emerge from the earth. He scrapes away more sand, revealing tubes and elliptical lobes that a moment ago were completely buried. The thing is so delicate that, as Tschinkel and his graduate students remove it from the ground, it breaks into dozens of pieces. An ant nest, perfectly cast in three dimensions, it will be reassembled later in the laboratory. Tschinkel has spent this fine April morning mixing dental plaster to the consistency of eggnog, adding glass fibers, propping a cupped leaf against the nest’s entrance as a funnel, pouring the plaster, and letting it set. That’s when he dug the pit beside the nest and liberated the cast. “It’s a typical ant nest—a vertical tunnel with horizontal chambers,” he says, carefully laying out bits of it on the grass. For more than a decade, Tschinkel, a myrmecologist, or ant specialist, at Florida State University in Tallahassee, has studied the behavior and social organization of ants. His curiosity was aroused by their nests—mysterious underground caverns never clearly seen by scientists. “It’s hard to visualize what’s underground,” he says. What did the nests look like, really? What could they reveal about ants and how they structured their lives? A few sketches had appeared in scientific journals but rarely to scale and with little detail. Tschinkel tried excavating nests and making his own sketches but found he couldn’t see their three-dimensional structure clearly. Then, 15 years ago, he got an idea. He mixed plaster and poured it into a fire-ant nest. When he dug up the casting and painstakingly glued the pieces back together, “it was a revelation.” Now, he says, we can describe ant-nest architecture much more precisely, leading to a better understanding of the insects and the mysterious principle known to science as self-organization—simple units of nature forming larger patterns through interactions with one another. An ant colony develops when each individual does its job in response to outside cues. The rules for this behavior, Tschinkel says, are “somehow internally programmed; they result from the way the nervous system is organized.” Each of thousands of earth-nesting ant species has a specific nest design, and each builds from a particular set of rules. “What is that set of rules? How do they come by them? How do they execute them?” Tschinkel wonders. “How does a group of individuals with no leader, no plan, create such complex structures in the dark?” Most ant colonies begin when one newly mated queen digs a single-chambered nest, seals herself in, and rears a first brood of workers. Queen ants need be fertilized only once: They store a lifetime supply of sperm in a sac, and in mature colonies, if the ambient temperature is warm enough—72 degrees Fahrenheit—some queens can lay 1,000 eggs a day for many years. The brood hatches in a week and, feeding on reserves in the queen’s body, grows to maturity in a month. Then the workers begin foraging—in the case of Florida harvester ants, for insects and seeds—to feed the next brood of eggs. And so the colony expands. Workers live about a year, but a colony can survive 10 or 20 years, until the queen dies. The colonies of most ant species, including the harvester, are social, cooperative, seamless organisms, differing from what we think of as an individual organism only in that “they’re not stuck together,” as Tschinkel puts it. The colony is a kind of creature—a superorganism. Tschinkel made his first cast in 1985—a nest of fire ants, known as Solenopsis invicta, meaning “the unvanquished.” They create huge, long-lived colonies with a quarter of a million individuals, and queens that live for seven years. While most ants defend only their nests, fire ants ferociously defend surrounding territory, too, often over 1,000 square feet, and their stings are memorable even to mammals. Tschinkel had completed groundbreaking studies revealing “the behavioral rules governing the flow of food” in their colonies. He had explored their nests—first chloroforming the inhabitants, partly for his own safety but mostly “to knock them down where they stood so I could see how they were distributed in the nest”—and thought he had a good idea of the nests’ geometry. But when he poured dental plaster into one and then dug it out, the picture was much clearer. “The nests of fire ants are a lot more patterned and less randomly arranged than I had thought,” he says. “They were obviously organized, regular, predictable—so interesting. I got into the architecture.”
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A few years later, he cast the nest of Odontomachus brunneus, the trap-jaw ant, named for its unusual facial structure. The trap-jaw’s gigantic mandibles protrude to the sides, giving it the look of a hammerhead shark. The jaws are remarkably strong: If the ant clamps something too smooth and round to hold on to and its jaws slip off, they snap shut with enough force to shoot the ant three inches backward. In this cast, Tschinkel recognized the same construction he’d seen in the fire-ant nest, “only here the internal nest consisted of a single unit—the shish-kebab unit.” That is Tschinkel’s description of chambers strung one after another along a single vertical tunnel, giving the cast itself a lumps-along-a-stick appearance. “So I got the idea of a basic, widespread architectural unit that might be fundamental to many ant nests.” He was still pondering the problem when he got interested in the Florida harvester ant—Pogonomyrmex badius, casually known as the pogo. One of the more impressive ant species, the harvester constructs an elaborate, seven-foot-deep nest in less than a week, moving pounds of sand in the process. Then foragers search their territory for seeds, which are stored—as many as 300,000 of them—in subterranean chambers. Workers crush the seeds into pulp and feed it to the larvae. In turn, Tschinkel thinks, the larvae probably return a nourishing liquid to the workers, supplementing their diet of sweet plant exudates, aphid honeydew, and juices sucked from prey insects. Tschinkel’s early attempts to clearly describe the areas in the nests where all this happens were unsuccessful. But in the early 1990s, he found a freshly abandoned pogo nest, and he filled the entire thing with a single five-gallon pour of dental plaster. Once the plaster hardened, the cast came out of the ground—in 180 pieces. “I cleaned them up, and they sat on my lab bench for three or four years,” he says. “Assembling it seemed daunting.” But Tschinkel, a hobby woodworker whose house is filled with elegant handmade furniture of his own design, devised a method of gluing the broken casting together with epoxy and mounting the cast in front of a tall plywood backboard, supporting it with projecting steel welding rods so that it would hang in space in the same orientation it occupied in the ground. “I started assembling subunits on the lab table,” he says, and over months—many times longer than it took the ants to build the nest—“I reassembled the cast into perhaps a dozen subunits and then figured out how these went together.” The nest of the harvester colony has 130 chambers connected by about 30 feet of vertical tunnels. He did the same with other species, including Aphaenogaster ashmeadi andPheidole morrisii, and some of those mounted casts occupy Plexiglas cases outside his office on the Florida State campus. They are, as Tschinkel describes them, “physically, intellectually, and aesthetically pleasing.” Tschinkel believes that an ant colony grows just as a single organism does, by rules that guide interactions among its cells and between it and its environment, a process called embryogenesis. A colony is “produced from the single, mated queen through the rules and interactions of sociogenesis”—the process by which a society grows and changes according to its internal rules. “And just as mature organisms differ, reflecting the rules of embryogeny,” he says, mature ant colonies differ as well, reflecting variations in the rules of sociogenesis. Tschinkel is trying to describe those rules. He studies, for example, how worker size, distribution, and labor patterns change as an ant colony grows, and how labor division by worker size and age helps shape the colony’s structure and habits. Such factors appear to organize the workforce the way a factory floor plan organizes personnel. Young workers start out low in the nest, looking after the brood and the queen, and then move upward as they age, taking on more-responsible jobs—“general nest maintenance, food preparation, seed storage. Finally, they move even higher to become guards and trash collectors and, at last, foragers.” He is also documenting how new ant colonies begin, including some unusual variations on the model in which the queen digs a hole and starts things rolling. Although newly mated fire-ant queens usually found new colonies alone, sometimes they do it in cooperation with other newly mated queens that arrive on the scene simultaneously. That’s a puzzle because it would seem risky: Worker ants tend to kill all but one such queen. Sometimes a mated queen will settle in an orphaned, queenless colony, although she’s unrelated to the workers there, and take over as a kind of royal parasite. Tschinkel has no idea why the workers are willing to serve such a usurper. In addition, a new colony’s workers often steal a brood from other new colonies, whose workers steal it back, and so on, until one colony wins. Then all the workers go and live in the winning nest, thus abandoning a mother.
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Ant-nest design has a basic theme, Tschinkel says: Vertical tunnels for movement and transport, and horizontal chambers for work, storage, and housing the brood. But nests differ in shape, number, size of chambers, and how they’re connected, depending on the species. With the Florida harvester-ant nest, for instance, the largest chambers are near the surface and closely spaced, becoming smaller and farther apart deeper in the ground. Small chambers are oval in shape; larger ones are multilobed and more complex. But exactly how the workers “know” to generate these shapes is not so obvious. “As they’re doing the work, each worker responds to what needs to be done,” he says. “What are the properties of individual ant workers so that once each has made her contribution, the sum is a particular outcome?” One of Tschinkel’s graduate students, Sasha Mikheyev, analyzed 17 nest casts ofFormica pallidafulva. She consistently found that when the descending tunnels are vertical, the adjoining chambers are round, and when the tunnels are inclined, the chambers are oval or teardrop-shaped and lined up along the tunnel’s axis. In a simple way, this observation illustrates one of the rules for how nests are built, Tschinkel says: If a tunnel is vertical, the ants doing the digging tend to distribute themselves evenly as they work, and if it is sloped, they tend to collect in the lower end.
Months later, on an August morning, Tschinkel is deep in the Apalachicola National Forest with a whole new idea packed into the bed of a pickup truck. Over the years, Tschinkel has cast ant nests with latex, plaster of paris, and dental plaster enhanced with glass fibers. Each has advantages, but none is perfect. So today he’ll be trying something new: molten metal. He has spent months fabricating a clever foundry based on a kiln of fireclay in a galvanized garbage can and an air blower made from an auto heater fan. Tschinkel sets up the works, piles in charcoal, lights it, and then waits an hour for 30 pounds of scrap zinc to melt. Meanwhile, he builds a mud dam around the entrance of a pogo nest and blows away loose sand through a plastic tube. Finally, he pours in the molten zinc. It flows so smoothly that Tschinkel worries it might be disappearing down a subterranean rat hole. After waiting 10 minutes for it to cool and harden, he starts digging beside the nest with his favorite shovel. “It’s like buried treasure,” says Kevin Haight, a graduate student, as gleaming metal emerges from the ground. Bristling from some of the tunnels are hairlike projections, perfectly captured—the tunnels of another ant species, the tiny, sneaky thief ant Monomorium viridum, which survives by raiding the broods of other ant species. Haight ties a rope to the heavy cast and helps haul it out of the ground. It emerges in just eight pieces. “Fabulous,” Tschinkel says. But later, when he has time to think about it, he concludes that zinc is too dense. The metal cools and sets up before it reaches the bottom of the nest. Next time, he says, he’ll make a first pour with molten aluminum and a second pour in zinc. He has many opportunities to perfect his technique for making 3-D casts. There are 50 ground-nesting ant species in the area alone, and roughly 5,000 worldwide, each with its own unique way of life and shape of nest. For instance, there’s the genus Atta, the leaf cutter, which builds the world’s largest nests, up to 35 feet deep and covering as much surface as a small house. “I’d love to do an Atta nest,” Tschinkel says, smiling, “but I’d need several tons of plaster.”
Serial.
N o 920315
That’s a start, but it’s still unknown which workers do the digging, whether they have this directional bias individually or as a group, or how the number of ants may influence nest size and shape. “I can imagine if there are only a few, they might dig only a tunnel, because they wouldn’t be crowded. But if there are more, they might dig chambers too,” Tschinkel says.
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The Man himself, Walter Tschinkel, diggin out an aluminum caste out of the ground.
BIBLIOGRAPHY
Anglesey, Leslie. “5 Leadership Skills We Can Learn from Ants.” About Leaders. N.p., n.d. Web. 7 May 2015. <http://www.aboutleaders.com/ 5-leadership-skills-we-can-learn-from-ants/>.
“Ant.” Encyclopaedia Britannica. N.p., n.d. Web. 7 May 2015. <http://www.britannica.com/EBchecked/topic/26867/ant>.
“ASU scientists discover that ants can change their priorities.” Arizona State University. N.p., 5 Nov. 2013. 7 May 2015. <https://asunews.asu.edu/20131106-ants-decision-making>.
Carey, Bjorn. “Stanford University.” Stanford. N.p., n.d. Web. 7 May 2015. <http://engineering.stanford.edu/news/ stanford-scientist-discover-anternet>.
Encyclopaedia Britannica. N.p., n.d. Web. 7 May 2015. <http://www.britannica.com/EBchecked/topic/26867/ant>.
Ferguson, Henry. “Colony size predicts division of labour in attine ants.” The Royal Society. N.p., n.d. Web. 7 May 2015. <http://rspb.royalsocietypublishing.org/con tent/281/1793/20141411>. Gordon, Deborah. “What Do Ants Know That We Don’t?” Wired. N.p., 6 July 2013. Web. 7 May 2015. <http://www.wired.com/2013/07/ what-ants-yes-know-that-we-dont-the-future-of-networking/>.
A N T S D E C L A S S I F I E D | Master Architects
Humphreys, Brett. “The Secret Life of Ants.” Discover. Kalmback, 7 Nov. 2003. Web. 7 May 2015. <http://discovermagazine.com/2003/nov/ the-secret-life-of-ants>.
“Information about Ants.” Assured Environments. N.p., n.d. Web. 7 May 2015. <http://www.assuredenvironments.com/pest-library/profile/ ants>.
Anglesey, Leslie. “5 Leadership Skills We Can Learn from Ants.” About Leaders. N.p., n.d. Web. 7 May 2015. <http://www.aboutleaders.com/ 5-leadership-skills-we-can-learn-from-ants/>.
“Interesting Facts About Ants.” Lingo Lex. N.p., n.d. Web. 7 May 2015. <http://lingolex.com/ants.htm>.
Jackson, Duncan E. “Communication in ants.” Cell. Elsevier Inc., n.d. Web. 7 May 2015. <http://www.cell.com/current-biology/abstract/>.
No. 37
Designer
Gino Santoro
Project
Ants, Uncovering the Truth
Instructor
Ariel Grey
Class
Typography 3
Typefaces
Courier, Songti SC, Minion Pro
Paper
Classic Crest
Printer
California Office
Binding
Perfect Bound
Software
Adobe Photoshop, Illustrator, InDesign
ANTS
UNCOVERING THE TRUTH
Ants, the most common household pest, can be a mere nuisance or more than that: there are some that just want to share the food, but others sting or damage building materials. In the same family with bees and wasps, the ant is a member of a group of insects with thousands of species, some of which are household pests. They can range in size from 0.1â&#x20AC;? (.25 cm) to 1â&#x20AC;? (2.54 cm), and are variously yellow, red, brown, black, or a blend. Being omnivorous, they eat human food as well as waste. In addition, the carpenter ant creates living area in wood, often choosing sites where the wood is wet and damaged. Ants have a clearly delineated 3-section body (head, thorax, and abdomen), six legs, compound eyes, and a pair of antennae. Some have stings, and some can spray poison. Some varieties have wings. They are nocturnal, being most active at night. Since ants like to parade in line, it may be fairly easy to find the point of entry that they are using. When found, seal it.