Alberta Bee News
August 2021
Detecting Wax Moth Larvae In Frames Of Sealed Brood By Rob Snyder, Bee Informed Partnership https://beeinformed.org/2021/07/02/detecting-wax-moth-larvae-in-frames-of-sealed-brood/
Another visual identifier of developing wax moths in colonies is when the capping is chewed down, appearing like the bee was trying to chew out of the cell (Image 2). This is actually caused by adult bees removing the wax layer on top of the capping containing the cocoon, as the bees have most likely detected the dead pupa below under the capping and are working on removing it. You often find these signs in older dark comb. (See images 1-4).
As a honeybee health field specialist, when I am assessing a colony’s health I look for irregularities in the sealed or open brood (Image 1 & 2). These irregularities may indicate the presence of diseases or pests. One common pest that can cause brood irregularities is the wax moth. Wax moth larvae develop underneath the honey bee colony’s brood cappings. The wax moth larvae often bind a honey bee pupa’s feet to the midline of the of frame, resulting in pupae that are not able to molt properly and therefore die in the capped cell before emergence. When identifying and locating wax moth larvae in a brood frame, the first thing I look for are honey bee pupae that have been uncapped in a straight line. Usually, those pupae have developed heads and are in the purple eyed stage (Image 1). This symptom is coined bald brood. The pupa is often uncapped in a straight line with the next few cells being noticeably light as if the bees were slowly chewing the cappings (see Image 2). In contrast, I have also seen these lines of capped brood with the capping becoming dark brown.
Image 2: Capped brood with irregularities. Notice the light colored, thin cappings in the center of the image; this is usually a sign of damage caused by wax moth larval tunneling. This image was taken before I dug out the wax moth larva.Photo Credit: Robert Snyder, CA Field Specialist
Image 1. Brood irregularities. Uncapped brood, before I dug out the wax moth larva. Notice the uncapped brood are in a straight line and are in the purple eye developmental stage. Photo Credit: Robert Snyder, CA Field Specialist.
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