MANITOULIN—As if readers of The Manitoulin Expositor have not had their fill of forest tent caterpillars, entomologist Joe Shorthouse went ahead and took this close-up portrait of a full-grown larva last Friday and sent it to The Expositor office.
Although grotesque, and belonging in an alien movie, the heads are somewhat fascinating when you think they have helped make this insect very successful.
Mr. Shorthouse explained that we are looking at a side view of the head of a caterpillar facing to the left. Caterpillars have six eyes on each side of the face—yes, they have 12 eyes! The shiny dots are the eyes. They are called simple eyes because they can only detect light intensity and cannot form an image.
A complex series of mouthparts designed to tear leaf tissues and manipulate pieces into the mouth are seen to the lower left. There is a tube-like structure called a spinneret on the lower lip that contains the spinning apparatus (the silk glands).
photo by Joe Shorthouse
Silk dries when exposed to the air and is used to mark trails, hang onto and lower themselves from trees and to make webs and cocoons.
The number of caterpillars on the east side of Manitoulin seems to be decreasing so hopefully the worst part of the cycle is over.
