It’s still early enough in the summer that tree owners with looming infestations of tent caterpillars can either cut the little buggers loose or give them a belly ache.

Wait too long, however, and be prepared for the Alfred Hitchcock-like invasion of the one-inch monsters, devouring trees bare and dropping onto the deck, into the food, and in your hair.

So says Don Meehan, the Washington State University Extension agent who has been dealing with tent caterpillar questions in Island County for so many years he gets a little colorful in his descriptions.

“They become a real nuisance,” he said. “Even guys like me, who think bugs are pretty cool, when there are thousands of them, its not too cool.”

The annual invasion is at a vulnerable stage right now. The caterpillars are tented within web-like structures that can contain hundreds of insects, making them vulnerable to pesticide or physical removal. The tents make them easy to spot and relatively easy to eliminate.

If the tents are on easy-to-reach lower branches, they can be attacked physically by scraping them away, squishing them, or cutting the small branches from which the tents hang.

If not, the young caterpillars are still very susceptible to a bacterial pesticide known as BT, for bacillus thuringiensus. Meehan said the bacteria is harmless to people or pets.

“It will not affect us or any other mammal and won’t necessarily affect other bugs,” he said.

It works by giving them a “belly ache,” Meehan explained. They stop eating and soon they die.

Later in the summer, after the caterpillars are more hardy, it will take more potent pesticides to kill them, he said.

“People have a tendency to blast away at them with everything under the sun,” he said. The best idea is to hit them early, he said, and avoid the chemical pesticides.

Left alone, the caterpillars will keep eating until a tree or shrub is defoliated. This is when they go into what Meehan described as the Alfred Hitchcock phase their cycle. Caterpillars drop off the trees in search of other food sources, often landing where they are least wanted — on food, on cars, and onto people. They’ll eat their way through all the deciduous trees until its time to spin their cocoons. The moths that emerge will lay eggs again, which actually hatch in midwinter. And the cycle starts all over again.

It’s rare for the caterpillars to kill a tree, unless the tree is already stressed and unhealthy, Meehan said.

So the choice of doing nothing won’t hurt. But, Meehan had one last bit of advice. When in the year, wear a hat.

Joe Hunt / staff photo

Young tent caterpillars are vulnerable and easy to find as they gather under their web-like tents.

They’re back!