Their life is one of consuming and processing food until they move on to the next step of development or are themselves eaten. Towards the end of summer, when the nights begin to get cool, caterpillars seem to go about their task with an increased sense of urgency. Most will survive winter as a pupa and they must reach that stage before temperatures get low enough to bring their metabolic processes to a halt.
Add to those the multitude of
species that feed on grasses and forbs and I doubt that you are ever very far
from a caterpillar when in the field. The
trick is in finding them. This Deerberry
shrub is showing signs of the recent dry weather. Dead leaves are piled beneath the plant and
live leaves all show signs of discoloration.
I wouldn’t pick this as the most likely place to find caterpillars, but
I always give the Deerberries a check when I’m out.
The shrub is full
of caterpillars. These are larva of the
Major Datana Moth, Datana major. Early
instars of this caterpillar are gregarious and feed as a group. When they reach their final instar, they tend
to disperse and feed individually.
pattern however, does harmonize with the mosaic of greens, reds and browns in
the leaves and the grays and blacks of the stems. As you come into range, the materialization
of the caterpillar image is similar to the moment your eyes reach the proper
degree of focus to reveal the subject of one of those 3D Magic Picture prints. It’s a definite “Ahhh” moment, not to be
confused with the more cerebral “Ah-hah”.
with black bodies and broken white stripes represent the final instar prior to
pupation. The brown and white striped
caterpillars will soon be proceeding to that final instar form.
These fragile skins are easily dislodged by
wind or rain. In fact, several fell from
the branch as I maneuvered it for better viewing. We haven’t had rain, but the open field in
which the Deer Berry grows has experienced an abundance of wind.
Dispersal of these larger caterpillars is necessary in order for each
individual to feed without disturbance.
The caterpillars have moved out through half of the shrub and a few
individuals have arrived on neighboring shrubs.
They will soon make their way to the ground where they will create a
chamber in the earth in which to pupate.
Adult moths will emerge next spring to begin the process anew.
interesting that so many colorful caterpillars eventually emerge as drab
adults. For some reason, the coloration of
these caterpillars makes me think of 1950’s era vinyl patterns.
When threatened, the
caterpillar raises its head and tail with thoracic legs thrust upward like
horns. In addition to the threatening
appearance, a bit of ingested material is regurgitated at the mouth and a
droplet of liquid is released from the anus.
I’m assuming that both of these substances are unappealing in some way
to predators. The anal droplet is
visible in the photo as a honey colored sphere on the end of the upraised
tail. Quite an interesting little
Salmon and Salad Dinner
9 hours ago