That time of year

I had started this post a little earlier, and then realized that it was referring back to a post from almost exactly a year ago, so I delayed it to make it line up. Humans do stupid things like that ;-)

Once again this year, the inchworm stage of the wavy-lined emerald moth (Synchlora aerata) has made its appearance on the flowers in the yard, and when I say “appearance,” I mean “trying hard not to.” This species camouflages itself with flower petals plucked from its host plant, making it able to sit distinctly in the open and munch on the flowers without attracting attention. The key to spotting them, aside from peering very closely at every flower that one comes across, is that they often use the outer petals for their camo, so the nice geometry of rim petal color and interior reproductive organs is marred – there are petals ‘growing’ from the center of the bloom. Also, not surprisingly, the plucked fragments don’t last very long and wilt, and may display a noticeable difference between the fresh healthy flower bloom and the browning cover of the inchworm. Since this species of flower has an exceptionally brief period in bloom, this difference may last only a day or so before the host looks much like the camouflaged larva.

The inchworm also has to work fast, since it’s in competition with the pollinators, and from appearances it has to obtain its nutrition before the various local hymenoptera and lepidoptera arrive. I’ve watched a miniscule Augochlorella aurata, a coppery green bee, servicing the same bloom while the inchworm twitched spastically to try and chase it off.

Here’s a closer look at the details – you can ever make out the eyes right near the lower tip of the head, about the same size as a grain of pollen. The wonderfully carunculated appearance of their natural exoskeleton would seem to be camouflage enough, and at this magnification (the entire worm is perhaps a centimeter in length) bears a resemblance to the jagged ambush bugs I was photographing last year (I’ve spotted almost none this year.)

Like the ambush bugs, once the bloom is wilting the inchworm moves to the underside, and unlike many other inchworms, this species seems to spend most of its time as motionless as possible, relying on blending in. The rearmost sets of limbs are the primary supports, remaining locked in place until the inchworm absolutely has to move, and otherwise supporting all of the larva’s weight in what would be a serious feat of strength and leverage for us. Notice how even the forelegs are tucked in tightly, reducing the vulnerability of the fragile limbs.

On the same photo outing as the posts here and here, I spotted another, and placed it onto my palm for more detailed closeups. Since it had fewer decorations I was able to illustrate both the differences in the leg sets and the spiky protuberances on its back, to which the camouflage is affixed. Despite my observations, I have never seen any of these actually applying its ‘makeup,’ so that’s something still on my shooting list. You have of course noticed the difference in base coloration, though I’m fairly certain these are the same species since it appears to be the only larva that does this. Whether the coloration can be changed at will, or appears after a new molt, is something I have not determined yet. I guess I might have to try transplanting one between flower species and seeing what happens, though when I tried that with one of the ambush bugs, it quickly migrated back to the flower I’d found it on.

And, of course, I would like to catch one in the process of spinning its cocoon, something that I haven’t accomplished for any species yet. Despite the easy access, I will admit to a certain reluctance to sitting in the yard for hours on end in temperatures exceeding 35° C (95° F). Yeah, so much for dedicated nature photographers, but if you really want to see it, I can be commissioned for an appropriate fee ;-).

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