Tips for bagworm control
Before I get into the topic of the day, I would like to put in a plug for soil testing at the UGA soil test lab. Soil testing itself is very economical at $9 per sample which includes shipping. It is a great tool to help a person obtain fertilization and liming recommendation for what they are growing in the soil on their property.
Recently, we have been shipping many soil samples taken by clients for lawns, pastures and vegetable gardens. If you would like the UGA pamphlet on how to collect soil samples, just email me and I can get that sent to you. The pamphlet will go over proper procedure, sample depths for your activity and how to dry the samples if they are damp. Note, we also have soil probes that can be checked out to help you in collection efforts. I will also encourage you to check us out on Facebook at Gordon County Extension/ Agriculture and Natural Resources for out latest tips and timely information.
Now back to our topic of the day concerning bagworms. We soon will be entering the time period to be on the lookout for newly hatched bagworms. These caterpillars are unique in their life cycle and can cause damage to our deciduous and evergreen trees.
Bagworms can be especially problematic to juniper, arborvitae, spruce, pine and cedar. I have seen a few Leyland Cypress that had bagworm damage and were either killed by the caterpillars, drought or disease. Large populations of bagworms can consume tree foliage and cause the tree death. I am going to be sharing information from the UGA Center for Urban Agriculture, but from a source by University of Kentucky entomologists M.F. Potter and L.H. Townsend. I will also add information from our 2021 Georgia Pest Management Handbook for homeowners.
From an entomology standpoint, bagworms are cool in their life cycle. The damage they can do is not fun. A bagworm is the larval stage of a moth that you seldom see.
The male can develop into a moth that can fly while the female will stay more grub appearing. The female will stay in the bag they make until just prior to her death.
Bagworms will spend the winter as eggs inside the bag that held the previous year’s female. The bagworms will hatch from the bag in middle to late May. When they hatch, the small larvae will crawl around looking for food. Soon after hatching, bagworms will use silk and plant material to make a small bag around their hind part that will appear like a tiny and upright ice cream cone. As they feed and mature, bagworms will enlarge the bag which will give them a place to withdraw into when they are disturbed per Potter and Townsend. Infestations can go unnoticed because the protective bags made by the caterpillars are mistaken as either pine cones or other plant parts. I normally will receive calls in later July or early August when folks notice stripped areas of foliage. By early fall, the bags can reach a size of 1.5 to 2 inches. By this time, the caterpillars will permanently hang the bags pointing downward from twigs so the bagworm can transform into the pupa stage before becoming an adult. When they turn into adults, remember the male is a flying moth. The male will go to bags containing the grub appearing female for mating. The female will lay hundreds of eggs in the bag. She will drop from the bag and die. The eggs will stay in the protective bag till the next May and will hatch to start the life cycle again.
What can a homeowner do? If you have the preferred ornamentals for bagworms, I would start investigation now. If you see the attached bags from last year, you may still have time for hand removal and destroying of the bags if you can do in a safe manner.
This can work if you have only a few infested trees or shrubs. This can work in the fall, winter or early spring. If you do not hand remove attached bags, you can use insecticides when the bagworms are small such as in June. Insecticides for bagworms will work better when the bagworms are less than .50 inch long. The bagworms are hard to see, but you can look for the upright bags that look like ice cream cones. Our information states that preventive treatment is often warranted on ornamentals that were infested with bagworms the previous year. Our information states the Bacillus thuringiensis products such as Biotrol WP, Thuricide or Sok-Bt can be an option. Safari by Green Light with the active ingredient dinotefuran is mentioned along with malathion 57EC along with other various pyrethroids. I will add to read the label of any product for safe and correct usage plus insects that product will control. You may see a temperature warning on some products too. Be mindful of our pollinators in the home landscape. Never spray blooming plants while bees are foraging. Direct spraying blossoms should be avoided at all times. Late afternoon or evening application reduce risk to pollinators. In some situations, you may can avoid sprays by rinsing off small bagworms off an ornamental with water from a hose. The larval bagworms may not be able to climb back onto the ornamental.