ENT 532 Fall 2024: Video of gall fly larva (Tephritidae)

I collected a gall from the stem of a goldenrod plant (Solidago sp.) found between a road and a field. The following day, I cut the gall open. Inside was a goldenrod gall fly (Tephritidae) larva, a small, white larva. It reminded me in some ways of the Bombus impatiens larvae I frequently see in my lab. It’s interesting that the larvae of these species (and of many others) are visually similar despite the adults appearing quite different. I suspect this divergence of morphologies throughout development is common when taxa share a distant common ancestor; distantly related vertebrates also look similar in early stages of development (i.e. as embryos) even when they have drastically different morphologies as adults. When I removed the larva from the gall and placed in on a flat surface, it began moving, pulling its posterior end in towards the anterior end so that it looked nearly spherical, and then reaching the anterior end forward and flattening out slightly to move forward. I found this behavior interesting, as it appears to be an instinctive response to stimuli associated with being removed from the gall (perhaps changes in the amount of light or the temperature). I am curious whether goldenrod gall fly have any chance of surviving if prematurely removed from their gall. Could they induce the formation of another gall or is that ability lost as the larva develops? If there is no chance of survival, then why would these larvae evolve to respond to stimuli associated with removal from the gall?