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The lackey moth

You know it well, or do you?

Whistler Naturalists

As a biologist and naturalist, there are a lot of critters that I am trained to know about that many people have never heard of. This week I was introduced to a new critter, for me anyway — the lackey moth. The lackey moth is inconspicuous and lives its very short adult life in quite an unremarkable way. This is probably why I had not heard of them; inconspicuous, short-lived, mobile, unremarkable, and difficult to detect. The immature lackey moth, however, everybody has heard of – it’s the tent caterpillar.

Lately you have probably noticed obvious masses of caterpillar colonies perched in the branches of deciduous trees all around Whistler and Pemberton. These are the silky homes of tent caterpillars, or the lackey moth larvae. The largest and most obvious "tents" belong to a voracious leaf-eating caterpillar called the western tent caterpillar, adolescent form of the western lackey moth ( Malacosoma californicum ). There are several different species of tent caterpillars that live in North America. Some species, such as the forest tent caterpillar, prefer a solitary life with tiny tents for one, rather than the hubbub of a large colony like the western tent caterpillar.

Closely related to each other, both the western and forest lackey moths have similar life cycles, and they go something like this: The soon-to-be lackey moth is born along with hundreds of siblings in the late summer or early fall. At this point the "moth" is just an egg; 150-350 eggs are laid by each female in brown egg masses about 2 cm long onto the branches of susceptible trees (alder, willow, cottonwood, aspen, etc.). Just before winter hits the insect egg transforms into a very small larva, or the adolescent form of the lackey moth, called a caterpillar. The larva remains inside the egg casing over the winter months. In the spring the small caterpillar hatches out of the egg along with all his/her siblings – and you can nearly hear their rallying cry "let the feast begin!"

Nights (and some days) are spent feasting on the luscious buffet of new leafy growth – so much so that some trees are completely denuded of their leaves. Unbelievably, this seldom kills the trees outright. The caterpillars spin silky "tents" which provide shelter from predators and the elements, and this is where they spend most days. By late spring or early summer the caterpillar is full-grown. If they haven’t done so already, the caterpillars will soon leave their main tent and move away from its hundreds of siblings. After finding an appropriate spot the caterpillar spins a white cocoon where it enters the pupa stage of its life. About two weeks later the developing insect emerges as the adult lackey moth – small, light brown, and inconspicuous.

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