Kids Ask Dr. Bug

about the curious things found in the garden

Why are butterfly wings colored with a powdery substance rather than just being like regular wings? Vera, 10

Butterflies and moths have wings covered in scales, rather than hair (like bats) or feathers (like birds). Scales are the powdery substance you feel if you touch one of these insects. Scales are useful for a few reasons. The scales make butterflies and moths slippery and might allow them to get away if something is trying to eat them. The scales create color patterns on the wings for camouflage, deception, or attracting a mate. Color is created in two ways – pigments or structure. Pigment colors are created by substances that absorb certain light wavelengths and reflect others. Structural colors are metalliclooking, iridescent, colors created by light passing through multiple transparent scales. The light reflects more than once and intensifies the color. In addition to the colors you see, there may be ultraviolet patterns that other butterflies can see, but we can’t. Remarkably, some butterflies and moths do not have scales on their wings and have clear wings instead.

How do insects walk on water? Hunter, 11

Insects can walk on water due to an amazing feature of water – water surface tension! Water surface tension is where the molecules at the surface of the water are closer together than in the rest of the body of water. This tension allows objects with a higher density than water, to float or walk on the surface. You may have seen water striders – an insect that skates across the water’s surface where they live. Their long legs are hydrophobic, which means that they repel water. This, combined with the water’s surface tension and the water strider’s carefully distributed weight, keeps the bug on top of the water. This bug is also lined with special hair that protects it from getting wet, rather, from staying wet when waves or rain get on it. The water just rolls off, so the bug doesn’t get weighed down or pierce the surface tension. Whirligig beetles are a water beetle that swims on the surface of the water, although they will dive underneath if they are alarmed. Their eyes rest just above and below the surface so they can see food and avoid predators.

A new beetle behavior was recently revealed – a beetle in Australia was found to walk upside down on the underside of the water’s surface (scan the QR code or go to https:// youtu.be/BHYaK6oizl8). Scientists are looking into how this beetle can do this. They think it may have something to do with air bubbles that could flip the beetle to the upside-down position and pin it to the water’s underside surface. Scientists are also already thinking of new technologies that could be developed when they figure this out, such as robots that can monitor environmental conditions in the water.

Butterfly wings are covered in scales that are useful for a few reasons.

How do insects breathe underwater? Brylen, 12

Unlike many animals, insects breathe oxygen through their abdomens, usually through holes called spiracles. Aquatic insects have adaptations of this to live in their environments. Many aquatic insects get air from the surface using breathing tubes called siphons, which are like straws. This is kind of like what you might see in cartoons when people are hiding under the water for a long time. Some aquatic insects have gills, although these are usually found in juvenile (not adult) insects such as dragonflies. Other insects live on the water surface and dive underneath – carrying an air bubble with them. In the example of the water strider above, special hairs cover the bug’s body and trap air next to it. If it accidentally goes underwater because of a wave or a raindrop, the tiny air bubbles keep the bug near the water surface and provide air to breathe.

Do you have questions for Dr. Bug? Send them to ReallT@Missouri.edu or bit.ly/KidsAskDrBug. Include your name and age. To help me learn what you learn from this column, please consider filling out this survey: bit.ly/ KidsAskDrBugSurvey. Thank you!

TAMRA REALL Horticulture Specialist

Dr. Tamra Reall (@MUExtBugN Garden) is the horticulture specialist for MU Extension in Jackson County. For free, research-based gardening tips, call 816-833-TREE (8733), email mggkc.hotline@gmail.com, or visit www.extension2.missouri.edu.

– SINCE 1984 –