Inchworms and Moths

Moths (Order Lepidoptera) pass through four developmental stages: egg, larva, pupa, and adult. The daily agenda is simple: eat, eat, avoid being eaten, and eat! Some species a caterpillar increases its mass by 30,000 times. In order to accommodate this growth, the larva must molt, or shed, its skin multiple times. After the last molt, the caterpillar goes through a pupal stage, the outer skin hardens and after a time the adult form emerges usually to a cue from the environment.
In the case of the Fall Cankerworm Moth (Alsophila pometana), late fall rains and a frost is the cue for the adult moths to emerge. The female is wingless but distinct in shape from the caterpillar. The male is a drab silvery brown with darker lines in a symmetrical pattern across wings which he spreads out flat against tree bark to blend in. The males flutter through leaf litter on the forest floor in search of a female. After mating, the female crawls up a boxelder tree and lays her eggs in sticky masses, the leaves will serve as food for the caterpillars as they hatch in the spring.

The Life-Cycle of the Geometrid Moth

Diagram of inchworm movements


What's for Dinner?
Fact or Infotainment?
The inchworm, or Fall Canker Worm, feeds on the leaves of box elder trees. The caterpillars of the geometrid moth (see lifecycle diagram) have fewer legs than other moths and this causes them to walk differently: instead of slithering along a leaf or twig like a regular caterpillar, these squeak along in a inchworm manner (is a moving graphic possible here?)The inchworm is a favorite food of birds, especially scrub jays. Chickadees eat the egg masses as winter forage food. In especially favorable years a single crop of inchworms can defoliate (eat all the leaves off all the trees) an entire stand of trees, causing great stress and even death to the trees.
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