This spring, and over the last two weeks, I have noticed a larger than average population of tent caterpillars in King and Kitsap Counties. Many cities use Bt to treat for tent caterpillar infestations or when populations are particularly large and the cities get a lot of complaints. Below are some ideas for naturally treating tent caterpillars (without chemicals). I remember a few years of heavy caterpillar infestations when I was a kid. What a joy to collect a few in a jar and feed and watch them grow! What a pain as they dropped from the trees into my hair :)
So, how do I know the critter I have been seeing are tent caterpillars? I didn't, so I looked into it today. Here is what I have found from the City of Seattle website:
"The egg masses are visible in winter, are grayish-brown and about one inch long. As soon as the eggs hatch in April or May, the caterpillars begin eating leaves and create "tents" - white, silky shelters that cover the forks and tips of tree branches and shrubs. They feed during daylight and return to their tents at night.
The caterpillars are easy to recognize. They have a yellow checkered pattern with a blue dotted line down their backs, and can be three inches long when mature. The caterpillars molt four times over a period of five or six weeks, then stop eating. They choose a place to spin a cocoon and lay their eggs, and moths emerge about two weeks later. The adult moths mate immediately, lay eggs, and die a few days later; the eggs winter over until spring, when the whole process begins again".
"Natural predators include many garden birds, which eat the caterpillars. Other predators are wasps and ground beetles. Homeowners who see infestations on their property should watch the number of tents forming and monitor the leaf damage. Individual tents can be removed by pruning in the early morning and evening, when the temperature is cool and caterpillars are inside them (a pole pruner is useful for high branches). Put pruned nests in a bucket of soapy water or seal them in a plastic bag and crush it. Do not remove large branches or perform excessive pruning as a means of caterpillar control - you may do more damage to the tree by pruning than the caterpillars would do by eating the leaves.
Another method of control is to hand-strip egg masses, or prune them out of plants during the winter."
I will post more pictures of my own new time I encounter a nest.