Naturespeak A naturalist's view of the world

June 30, 2016

A Crocus Moth on a Summer Eve

Filed under: Uncategorized — wykes @ 2:19 pm

Crocus Geometer Laying Eggs 1 photo IMG_3578_zpsdhvzhs7i.jpg

The night air was just settling in after the sun dipped behind the oaks and pines lining the opposite side of Dollar Lake. A group of Green Frogs were performing their syncopated “ga-lumping” and the last dragonflies of the day were hovering about the Spadderdock. I was standing on the dock waiting for the muskrat to re-appear. This particular individual had an unusually large pair of ears – odd for an animal known for very small appendages in this regard. I’d taken some pictures of the rabbit ‘rat earlier in the day but wanted another crack at him. I’m sure he was less anxious for a re-meet and was deliberately waiting for the disappearance of the human at nightfall. I was about to give up, seeing that the light was dimming fast, when a movement in the brushy willow to my left caught my attention.

A fluttering yellow moth was treading among the narrow leaves. The critter decided upon a single dangling leaf and momentarily hung motionless. Although it was located about ten feet away, I noticed that it curled up its abdomen in the manner of an egg-laying female. A view through my zoom lens revealed that it was a Crocus Geometer Moth depositing a new generation.

The view was obstructed, and the light was poor, but in the absence of Peter Muskrat this nature scene would have to do. The satiny green eggs were planted on the leaf surface near the mid-rib. Her extended ovipositor placed each egg so that it was paired with another. The activity proceeded at a slow deliberate pace and I ran out of light before seeing how many she laid (nor could I located the leaf the next morning due to the long-distance nature of its placement and the fact that all willow leaves look pretty much alike!). I counted at least nine by last light.

Crocus Geometer Laying Eggs 2 photo Crocus Geometer Xanthotype sospeta_zpskigqm3xl.jpg

Crocus Geometers are members of a group of moths better known as inchworms. It just so happens that my previous post was about a larval inchworm and you might get the impression that I am a bit of a geometer geek. I am not, but will happily bear the mantle for the time being. Perhaps I will spot some of the larvae after they hatch out this week but I doubt it because these caterpillars are also twig mimics!

One last comment concerning this small natural event. There are several species of Crocus Geometers which are virtually identical, so my identification of this one as a “Crocus” Geometer is admittedly tenuous (there are False Crocus Geometers etc.). It takes an expert making a detailed examination of the genital parts to tell them apart. I offer it up to anyone wishing to enlarge these images in order to confirm the particular species. I, for one, am satisfied just witnessing one of nature’s small miracles.

June 5, 2016

Sticking Around

Filed under: Uncategorized — wykes @ 8:58 pm

Twig-mimic Inchworm in Mimic mode photo IMG_3420_zps4uaiw7ik.jpg

There are over 1,200 species of Geometridae moths in North America – a group better known by their so-called “Inchworm” larvae. Because there are so many I feel justified in not identifying the particular inchworm pictured here. The exact name really doesn’t matter in this case anyway. This group of larvae are well known as twig mimics and this individual was such an incredible example that I felt compelled to bring it to your attention right away (in other words – hang the I.D.). Whatever it is isn’t as important as whatever it isn’t!

Upon prepping some twigs for a recent campfire I came upon this tiny inchworm clinging to one of the branches. I wouldn’t have noticed it at all if my disturbance hadn’t prompted an un-planned movement on the part of the caterpillar. Upon regaining composure it resumed its perfect twig imitation and once more vanished before my eyes.  The camouflaging skill of this fellow is successful due to two levels of mimicry.

Like all inchworm larvae, this one is typified by a long slender body and a distinct lack of legs at mid-body. There are three pair of prolegs next to the head, two sets at the hind end, and a long legless gap in-between. Most inchworms are cryptically colored to blend into leaves, bark, or twigs. This one is patterned in twig mode with mottled gray speckling and a clever set of fake bud scars located about a third of the way down the body.

Twig-mimic Inchworm photo IMG_3418_zpsuojnnw1d.jpg

This color pattern alone would serve well enough but an additional behavioral step improves the ruse to the point of near perfection. Make-up is only part of an actor’s skill. Upon disturbance, the caterpillar stiffens out and holds its body at a low angle away from the twig. The prolegs are gathered tightly into a bundle under the head to give the overall impression of a terminal bud and the creature remains frozen in place.

One might be tempted to believe that a green leaf might spring from the head of this living twig which isn’t.

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