What is it for?
The complexity of structures, textures, and colors on the surface of an insect are of obvious interest just for their elegance and beauty. Of course you think about that as you also explore these features for the more practical objective of making an ID. Two considerations for entomologists, which are irrelevant to the insect; of course they know they are beautiful, and they ID each other without reference to measuring wing venation and the like.
Another thing to think about, easy to forget when looking at dead specimens, is the fact that in the living insect, most of the tiny details are in the service of some function. So a friend asked: Why are the eyes of hoverflies hairy? I can't find an answer. Could it just be that hairiness is incidental to the formation of the eye? It seems not; some syrphid eyes are absolutely bare, others are carpeted with hair.
My own main concern is bees, in particular Andrena. In keys, you are asked to look at the pygidial plate, a flat surface that might be smooth, or patterned in many ways. Having recently discovered this trait, I have paid close attention to its diagnostic value. But as much as I like to think of myself as curious ... it had not occurred to me to wonder about the adaptive value of this feature. Until it was pointed out to me (thank you WIll Peterman) that the pygidial plate is a digging/smoothing tool, used by ground-nesting bees to form and water-proof brood cells. As far as the specific advantages of the different forms of pygidial plates ... a new thing to consider.
Comments
I found this:
A Facebook explanation of this:
Hi Terrance. Insects have a number of sensory hair on their body. The hairs we see on the eye of the syrphid fly are trichoid sensilla (see the diagram below). These hairs are in a socket and have nerves attached to them that fire when the hair is bent a certain way. Many flying insects have sensory hairs on their face for detecting air movement as they fly. It basically gives them information on how fast they are flying or if they are flying in the right direction (has to do with yaw, pitch and roll).
The Facebook source is
HERE
Still unclear:
Why on some and not others?
Why within the ommatidia? My guess here would be that there is already a nervous system apparatus in place.
Add a Comment