If you’ve seen dead plant material “walking” up the sides of houses or trees recently, you may actually be looking at the case of a bagworm moth. Cases are made from leaves and twigs held together with strong silk. While some bagworms require specific host plants, others can survive with any number of hosts. For example, the evergreen bagworm below can feed on several species, such as juniper, cypress, and pine.
Females spend their entire lives inside their cocoons, even mating and laying eggs inside. In the spring, when the eggs hatch, the larvae descend from the case and find a host plant to begin their own cases. Emerging as furry-looking moths, males can leave their cocoons after about a month in order to find a mate.
When fully grown, the evergreen bagworm’s case can reach over 2 inches in length. The bagworm itself reaches about an inch in length at maturity. Although they have excellent camouflage, they are preyed upon by insects such as wasps and hornets as well as some birds that pry larvae from their cases.
These moths can be considered pests as they have insatiable appetites and can cause serious damage to their host plants.