When you think of hibernation, you probably think of mammals first: maybe a slumbering bear, or a certain groundhog-turned-meteorologist. ???? The idea of a cozy winter snooze might not conjure up the image of *checks notes* ...fly pupae???
But a long, deep sleep is indeed on the horizon for select insects. Last month, TNC Maine's Kelsie Daigle (Land Relations Manager) had the pleasure of joining Tom Schmeelk, a Forest Entomologist with the Maine Forest Service, for a fascinating day in the field. Together, they set up a "Cyzenis albicans emergence cage" - a small but mighty tool in our fight against the invasive winter moth (Operophtera brumata). This cage will house fly pupae through the chilly Maine winter, allowing them to hibernate until spring. ?
Come springtime, the magic begins! As temperatures rise, the flies will emerge from these pupae, with males coming out first. Tom will return to the site, armed with apple slices that act as a sweet nectar source to feed the hungry males until the females make their grand entrance. Once mating is observed, Tom will open the cage, releasing the flies into the trees. There, they will seek out nectar from trees like red maple and the females will lay their eggs on leaves that winter moth caterpillars have damaged through feeding.
And here’s where the process gets a little less cozy, and a lot more creepy. The ingested fly eggs will lay dormant inside the winter moth caterpillars until they drop to the ground and pupate, after which the fly egg hatches into a maggot and consumes the winter moth pupae... from the inside out. ?? This leads to the ultimate demise of these pesky caterpillar populations. It’s a natural form of pest control that sounds more like the plot of a horror movie than a Hallmark one. ??
Bug brutality aside, the day of fieldwork ended on a tender note: Kelsie’s favorite moment of the day was watching Tom kneel beside the cage and whisper “Have a good sleep!” to the hibernating cocoons. It was a sweet touch to this scientific process. ???
?? Kelsie Daigle / TNC