Over the past several weeks, growing silk tents can be seen adorning many roadside trees, nestled between branches. These aren’t off-season Halloween décor and spiders aren’t the only creatures that create silken structures. The offending organism is much less scary: a caterpillar. The eastern tent caterpillar, to be exact.
The eastern tent caterpillar is a native, leaf-eating caterpillar. They are hairy with a white stripe down the center of their back. They live communally in the silken tents they build with their nestmates and as the larvae grow larger and larger, so do their tents. They eat leaves of the tree in which they perch; their favorites being cherry, apple and crabapple trees. Other common hosts include ash, birch, blackgum, willow, maple, oak, peach and plum.
While the infestations are always in tents, they can also be intense. Usually, the damage they cause is restricted to the eyesore that many consider their silken homes, but in some years, outbreaks arise and cause more significant damage. Outbreaks are considered cyclical and occur on average every 10 years. A single year of defoliation typically doesn’t cause long-term damage to tree health, but repeated defoliation can kill or weaken the tree, making it susceptible to other insect or disease pests.
Because damage has relatively little impact on overall tree health, control is usually not necessary. Trees that are defoliated by these very hungry caterpillars can re-leaf by midsummer. For high-value trees like landscape or fruit trees, insecticides are available. For a non-chemical approach, the silken tents can be removed and destroyed, but be sure the caterpillars are inside when this happens. Caterpillars and egg masses themselves can also be plucked off by hand for smaller trees.