Bug alert: Destructive caterpillars that camouflage with plants now hatching

COLUMBUS, Ohio (WCMH) – Caterpillars that are camouflage experts and known to cause damage to a variety of plants are now hatching in Ohio. 

Joe Boggs, an assistant professor with Ohio State University Extension, is warning residents to be on the lookout for bagworms, which are the caterpillars of bagworm moths. The insects create a bag around themselves using silk and pieces of their host plant, which camouflages them from predators. They often resemble small pine cones. 

The pests, which are native to North America, do not cause harm to people or animals, but can cause significant damage to plants. Bagworms feed on a variety of trees and shrubs, with a particular fondness for evergreens, such as juniper, spruce and pine.

Female bagworms lay eggs in their bags in the fall, which survive through the winter and hatch in early summer. While bagworms are hatching across the state now, they become more noticeable in July and August as they mature and get larger, according to Boggs. 

“Unfortunately, we don’t often see them until we see damage,” Boggs said. “Start looking closely at your plants because they’re very sneaky.”

Male bagworms transform into moths in late summer. Females never develop wings or moth-like characteristics, as they remain inside their protective covering where they mate and lay eggs. Both males and females die shortly after mating.

A single female can produce between 500 to 1,000 eggs, creating the potential for sudden outbreaks and population spikes. The caterpillars often spread by being carried by the wind to new plants. 

“You may not have bagworms at all from last season,” Boggs said. “You may say, ‘Well, I’ve really never had this problem.’ However, just down the road, there’s a high bagworm population. You can have these little caterpillars arriving on the wind into your landscaping.”

Early signs of a bagworm infestation may include plants browning or foliage thinning. Boggs said an easy way to get rid of bagworms is to pluck them off their hosts and step on them.

Boggs also said insecticides are another option, but some sprays may also kill arthropods that help keep bagworms and other pests at bay. He suggested “biorational” insecticides to help preserve the lives of beneficial insects that are not the target of the treatment.  

The best long-term solution for keeping the pests away is to plant a variety of flowering plants, which attract insects such as certain wasps that are predators of bagworms, according to Boggs.