Western Tent Caterpillars

Western tent caterpillars are about 2 inches long and vary in color and markings. We most commonly see these caterpillars either pale blue or yellow-orange with black and white markings, covered with orange-brown hairs.

Habits & Habitat

Starting around April, tent caterpillars build tents of dense web in the crotches of trees and begin feeding as a colony. They feed on the leaves of a variety of deciduous trees including fruit trees such as apple, plum, pear, and cherry. As the tent caterpillars feed and grow, the tent gradually expands. They feed for about 4-6 weeks and remain in the tent until they’re done feeding. When they’re done feeding, typically mid-May through June, the tent caterpillars drop off the trees and begin searching for a place to spin a cocoon (aka pupate). During this time, you may notice the caterpillars wandering around roads, driveways, parking lots, and on the sides of buildings. They will spin a cocoon in a variety of places including trees, small plants, and leaf litter.

Tent caterpillar moths emerge from their cocoons around June, and mate and lay eggs July through August. The eggs are laid in masses, covered in a glossy brownish-gray shell, on branches and twigs. They overwinter and when new foliage starts to appear in the spring, the eggs hatch and tent caterpillars emerge.


A single colony of tent caterpillars can strip the leaves of smaller trees, therefore making them a threat in nurseries and newly planted orchards. On larger trees, there is cause for serious concern if multiple colonies (tents) exist on the same tree. In these cases, damage can include stunted growth, branch die back, abnormal fruit development, and reduced fruit production. If infestations occur in successive years and are not controlled, it’s possible for the tree to die.

Reduce the Risk

Get a head-start on tent caterpillar season. If you notice egg capsules, remove them by hand. If you notice tents, you can remove them with a brush or prune the branches containing the tents. A trained and licensed pest professional can also help by treating the trees when the tent is first noticed, before the caterpillars emerge from the tent, or as soon as possible after they emerge.

It’s best to take action sooner than later to reduce the risk of tree damage. Once the tent caterpillars are done feeding and drop off the trees – it’s too late. At this point, the damage has been done and it’s not possible to control the hordes of caterpillars wandering around driveways and crawling on the sides of buildings.

Are There Tent-Shaped Webs in Your Trees? Call us today for a free inspection! For Oak Harbor call (360) 675-3235, for Bellingham call (360) 734-2670, or visit our Contact Us page for more local numbers.

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