Spring Pest Alert: Forest Tent Caterpillars
April 26, 2017
This is the time of year when many chewing pests, such as tent caterpillars (Malacosoma disstria), emerge. So it’s a good idea for you to keep an eye out for clusters of these caterpillars. Their tiny eggs were laid in your trees by orangey-brown moths; after the young emerge and grow larger they begin to crawl around, many of them fall to the ground, where you'll notice their distinctive snake like markings. Up in the tree canopy, you can also spot their web-like nests in the branch crotches where the newly hatched larvae congregate and enjoy protection from predators in these protected tents. You may also find large clusters of the caterpillars congregating on the trunks of your trees.
Some of these leaf eating moth larvae can be food for birds and other wildlife, and are not always a big concern for your trees; but a large population can do unsightly damage to your trees, especially if the tree is already stressed. The damage is rarely fatal to the tree unless it's very young and not well established - or has other serious health issues. If you are observant and detect these pests early, we can typically utilize natural methods to control the infestation.
We prefer to use a program of Integrated Pest Management (IPM), which begins with the least harmful methods and products are used first to eradicate the pest. If that doesn’t work, we discuss additional, but sometimes more intensive, options with the home or business owner. But, first and foremost, using Eco-friendly means is our top priority.
Trichogramma wasps (Trichogramma pretiosum) are tiny gnat sized insects that are excellent at naturally controlling many species of moth and butterfly caterpillars like webworms, bagworms or borers that might be attacking your trees. These barely visible parasitic creatures work by inserting their eggs into the eggs of the undesirable pest, killing them before they reach the plant feeding stage. Another natural and low-impact method of control is using a spray of Bt (Bacillus thuringiensis), which targets caterpillars specifically, while remaining safe for birds, pets and people.
Knowing what to look for in each season is the best way to catch problems early so these natural methods are most effective and your trees won't suffer unnecessary damage.