Eastern Tent Caterpillar May Be Arising in Western KY in 2023

Current Situation

People are noticing that many deciduous trees (trees that lose their leaves at the end of their growing season) have whitish spots in their branches. When observed closely, these spots are tents built in the forks of tree limbs (Figure 1). I also noticed these trees with these structures driving along the Western Kentucky Parkway from Eddyville to Leitchfield and on Hwy I-24 toward Paducah.

These silky structures are created by colonies of eastern tent caterpillar (Malacosoma americanum) for protection from predators and environmental conditions. Birds, mice, or other predators may be deterred by this tight webbing. Caterpillars exit the silken tents to feed in early morning, evening, or at night when it is not too cold. They return to the nest after feeding and remain in the tent during the day or inclement weather. As the caterpillars grow, the nest increases in size.

Biology & Description of Caterpillar

The eastern tent caterpillar overwinters as an egg; eggs are laid in dark mass clusters (Figure 2) during spring when plants start to break dormancy. When eastern tent caterpillars emerge, they start to feed on new growth.

Preferred hosts are plants in the Rosacea family (apple, cherry, hawthorn, peach, pear, plum) and other deciduous trees, such as maple and redbud.

Larvae are gregarious, and they group together with caterpillars from other egg masses to form large colonies. Early larval instars are dark and hairy (Figures 3A and 3B) and, as larvae mature, they have two thin yellow stripes along the back (Figure 4). Mature caterpillars are approximately 2 inches long (5 cm). Larvae of eastern tent caterpillars may be confused with forest tent caterpillars (Malacosoma disstria), but the latter has white dots down the back instead of solid lines, and they do not build silk tents. The larval stage can last between 4 to 6 weeks and the pupal stage can last up to 3 weeks. Adults emerge in May and June, mate, and lay eggs. There is only one generation per year.

Source: wordpress.com

Photo Credit: GettyImages-Ron_ThomasE+