Bagworms hatching…scout conifers or other plants with weird ‘pine cones’

If you have conifers or other plants that seem to have grown weird, dangling pinecones, look again because you have bagworms. Bagworms have been hatching for the last week or so. You can find the tiny caterpillars with tiny upright bags anywhere there are bags left from last year.

First instar bagworms with tiny upright bags. Photo: AG Dale

First instar bagworms with tiny upright bags. Photo: AG Dale

The Bagworm, Thyridopteryx ephemeraeformis, is a very common pest of conifers and other ornamental plants throughout the eastern United States. These pests overwinter as eggs within the mother’s bag. Larvae emerge from the bag during the May and June (depending on location and temperature). The larvae crawl or drift via silk strands to nearby foliage where they begin to feed. Bagworms are relatively sedentary during their lifetime, most often remaining on the same tree until they pupate. Adult females are wingless and never leave the tree. Male bagworms develop into a small brown moth.

Large bagworm feeding on maple. Photo: SD Frank

Bagworms feed on plant foliage and heavy infestations can defoliate trees and shrubs. Young caterpillars produce a silk bag on their posterior end that gradually collects plant debris. This creates a bag covered in pine needles or leaves that protects them from predators and looks (sort of) like a pinecone. Since they don’t move much as larvae and the females don’t fly, they can build up dense populations. Since they are so camouflaged and protected from insecticides, management of these insects can be difficult and time consuming. One of the most effective, yet time consuming methods of treatment are hand-picking or cutting the female pupae bags off of the branches. When this is impractical or impossible, there are chemical control options available that should be applied when caterpillars are young (now) because they are more vulnerable. As with many other pest insects, bagworms are susceptible to predation from parasitoids and birds which can also assist in their control.

PhD student Adam Dale contributed to this post.

May 21st, 2015|Categories: Feature, Landscape IPM|Tags: , , |

Baby bagworms

Newly hatched bagworms. Photo: AG Dale, NCSU.

Newly hatched bagworms. Photo: AG Dale, NCSU.

Bagworms have been hatching for the past week or so. I found the first hatchlings at a hot site on the south side of an NCSU building.  First instar bagworms quickly make tiny bags and begin feeding. The bags are held upright and look like little ice-cream cones until later instars when large bags hang below branches. You can scout for bagworms any time of year because the bags ‘hang’ around for a long time. Bagworms are relatively sedentary during their lifetime, most often remaining on the same tree until they pupate. Adult females are wingless and never leave the tree, while male bagworms pupate and develop into a small brown moth. Females lay eggs in the bags each fall that hatch in late spring (now!). So you know if you have bags you have eggs and thus new bagworms.

Bagworm bags that overwintered with eggs inside. Photo: SD Frank

Bagworm bags that overwintered with eggs inside. Photo: SD Frank

Heavy bagworm infestation like the one in this picture can defoliate evergreen foundation plants and privacy hedges making them not-so-private anymore.   One of the most effective, yet time consuming methods of treatment are hand-picking or cutting the female pupae bags off of the branches.  Since this may sometimes be impractical or impossible, there are other methods of treatment to be considered.  There are chemical control options available that should be applied during the early instar stages of the caterpillars since these are easier to kill and have not yet defoliated your plant.  As with many other pest insects, bagworms are susceptible to predation from parasitoids and birds which can also assist in their control.

Defoliation by many hundred bagworms. Photo: SD Frank

Defoliation by many hundred bagworms. Photo: SD Frank


More information in this note:
http://www.ces.ncsu.edu/depts/ent/notes/O&T/trees/ort081e/ort081e.htm

May 14th, 2014|Categories: Landscape IPM, Nursery IPM|Tags: , , , , |