Fall webworms
Ihave stated several times that I enjoy all of our seasons in Georgia. If I had to pick one, I may like fall the best. On the farm, it will be fall calving season. Most of those early calves will be the result of embryo transfer or artificial insemination to a nationally known bull so we anticipate the new offspring.
It is also football season and I enjoy going to see the Georgia Bulldogs play in Athens. I also know basketball season is just around the corner and my two favorite players to watch are my daughters and any young lady I coached over the years. With all of the exciting activities of fall, there are some late summer and fall issues that can be a nuisance or damaging pest problem for homeowners.
Today, I am going to share information on fall webworms from a
UGA publication by Fawad Khan, Shimat Joseph and Will Hudson, UGA Department of Entomology.
When you write as many articles as I do, it can be tough to come up with weekly topics.
This topic came to me by divine inspiration. No, not really. Actually, as I traveled from home to work, I noticed fall webworms on a pecan tree in the landscape at a neighbor’s home. The fall webworm is a caterpillar that can be a problem pest for ornamentals and trees in Georgia. It is called a “polyphagous” caterpillar because of the feeding on more than 600 species of plants. I think we all ask ourselves at times what other career paths we could have chosen. I probably would have been happy as a high school basketball coach or a large-scale cattle seedstock producer. I could also have been happy as an entomologist because insects can be interesting.
Fall webworm larvae will construct a silk web nesting area to give themselves a place to consume plant foliage, to escape predators and for heat retention. For some people the presence of the web masses can be a nuisance and unsightly.
The feeding damage will make the trees or shrubs look not so great and if the infestation is heavy it can cause damage to the tree. According to our information, fall webworms have caused damage before in row crops, herbaceous plants, shrubs plus fruit and ornamental trees in orchards, nurseries and landscapes. For the casual observer, you may miss some of the web nesting areas on tree branch edges. Yesterday, I saw several web masses on one individual tree.
Life cycles of insect can be interesting if you take the time to slow down and study the process. Fall webworms are active in summer and early fall. The female moth that lays the eggs is white and hairy.
A single moth can lay approximately 600 eggs on the underside of leaves in masses covered with white hairs from the female moth’s body. Eggs hatch in approximately a week. The larvae will be red or black headed and covered in fine hair. Very quickly, the hatched larvae will start working together to make a silken web over a branch tip. This is where they begin to feed. The larvae will consume all of the foliage inside that web. As the fall webworm larvae grow, the web will expand to cover more of the foliage on the branch. Caterpillars will feed up to six weeks until they will pupate. Pupation will happen in various places such as under bark crevices, soil or rocks. There is variability with the length of pupation.
It can be as quick as 12 days or as long as 80 days. Our information states the pupation length is affected by environmental conditions. You will get an adult moth emergence. Also, the fall webworm will spend the winter as pupa and you can have multiple fall webworm generations in a year.
What can a homeowner do in regards to fall webworms? This can be dependent on how much time and effort you want to commit to fall webworms. In general, a small amount of foliage feeding by caterpillars are not a deal breaker for overall health of our trees and shrubs. Again, our literature does state that severe infestations can cause considerable damage to trees. You can start inspecting your trees and shrubs in the middle of the summer for infestations. Keep inspecting until early fall.
There are stated to be traps available to determine early moth flights. To be honest, I would have to Inquire for more information on where those traps could be obtained for a client. One cultural control practice mentioned is to simply prune off infested branches to reduce extensive webbing. Keep in mind the intensive pruning is not recommended for example on a fruit tree because it reduced productivity of the tree.
The cheapest and easiest thing to do may be to simply disrupt the protective webbing and let the nature predators take over. For example, if you see a web netting full of fall webworms on a tree limb, take a rod or long pole and simply disrupt the netting. This exposes the caterpillars to not only birds, but lizards and spiders. Some of the Bacillus thuringiensis insecticide products are an option, but spraying a tree can be a problem and should not be attempted by a homeowner.