A lot of the documentation I read about tent caterpillars online says that they’re relatively harmless, which is true when they appear on certain kinds of trees. However, when it comes to fruit trees, tent caterpillars can become a horrible problem. In fact, tent caterpillars nearly killed our plum trees (which are still recovering three years later).
The problem is one of tree growth. A lot of trees get a secondary growth of leaves. When the tent caterpillars do their job during the mid-spring to late-spring months, they damage the first growth of leaves. The trees can recover with the secondary growth. However, many fruit trees get just one set of leaves for the entire summer, so when the tent caterpillars damage them, the tree is stripped for the summer and can’t store enough energy for the winter months.
Tent caterpillars also tend to strip fruit trees, partly because they’re smaller than some of the other trees that are affected by them. In fact, that’s what happened to our plum trees. The foliage was stripped before we knew what was happening and the trees simply didn’t recover. After viewing other trees the tent caterpillars have attacked, it becomes obvious that they really are just a pest at times.
Part of the solution is to inspect the trees carefully during pruning. Unfortunately, even a close inspection won’t reveal all the tent caterpillar clusters and some hatch. During the spring months I take regular tours of the orchard to look for the tent caterpillar nests, especially during the early morning when the night moisture reveals the nests with greater ease. (The inspections are also good exercise and are quite pleasant, so it’s not really work in the traditional sense of the word.) I hand pick the caterpillars and ensure I crush them. Removing them from the trees simply invites them to come back later.
The trees that seem most affected by tent caterpillars are plums and apples. Cherries are also affected, but the tent caterpillars haven’t acquired a taste for the Mesabi cherries for whatever reason (the yellow-bellied sapsuckers tend to avoid them as well). Untouched are the pears, which don’t seem to attract nearly as many pests at other trees on our property do.
A proactive approach to dealing with tent caterpillars is essential if you want to maintain tree vitality. Make sure you take that walk each day to mellow out, improve your health, and keep your trees healthy. Let me know your thoughts about tent caterpillars at John@JohnMuellerBooks.com.