Bagworms are Here: Could your trees be their next stop?
July 19, 2017
If you live in or around the Dallas/Fort Worth area, you might be seeing small pinecone looking “bags” hanging from certain trees or shrubs. Rural parts of Cedar Hill, Plano, and Frisco are just a few of the areas being hit with above average bagworm infestations, according to our Arborists Chad Simmons, Laura McLarry, and Ken Smith. Chad recently treated a property in Plano that had a growing infestation and took these photos so you would know what to look for in your trees.
What is a bagworm?
A bagworm is actually simply the larval stage of a moth, the evergreen bagworm, native to Pennsylvania. Thyridopteryx ephemeraeformis (Haworth), can be a serious pest when conditions are right and they reproduce rapidly. Once the moths lay eggs in spring, the larva form cone shaped “bags” that look a lot like a pine cone. This often keeps them from being noticed and they are able to travel to other plants.
The interwoven cone shaped bags, or cocoons, are made of silk, leaves, and twigs from the host plant, leaving a perfectly camouflaged place for the larva to grow undisturbed. The larvae themselves are shiny black and dull amber. As they mature, the turn a dull gray and the adult male becomes a grayish moth while the female stays grub-like, in the bag.
Host plants bagworms love include arborvitae (Thuja), juniper (Juniperus), pine (Pinus), spruce (Picea), leyland cypress (Cupressus × leylandii), and Italian cypress (Cupressus sempervirens)
Life Cycle at a Glance:
SPRING: Eggs hatch late May to Early June. The small larva leaves the bag and be carried by the wind on a silk thread to a new host plant. Once they attach to a new host, they begin feeding and creating their own new “bag”.
SUMMER: Larva continue to feed on your plants and grow through summer. These maturing larva can move their little bag around the host plant, or even move it to new host plant. The bag is then closed and in 4 weeks they turn into their next phase...pupae.
FALL: In September and early October, the larvae will pupate in it’s bag. Several days later the males emerge to seek out females still in their bags for mating.The females then lay up to 1000 eggs in her bag. She then either dies inside her bag, or drops out of it and dies on the ground. The cycle starts again with egg hatch in spring.
Damage and Treatment
So, what kind of damage do bagworms do to our trees and shrubs? They feed on your plants, drawing out water and nutrients and leaving behind small brown spots on the foliage. More mature larvae strip plants large amounts of leaf tissue, leaving only the larger leaf veins. The damage can be unsightly; if plants are already stressed it can cause further plant decline.
To treat bagworms effectively, we recommend an application of horticultural oil in late December or early December before the weather warms up.
We highly recommend checking your trees for signs of bagworms. To be safe, it’s best to call in the experts if you find an infestation in your trees.
Posted: July 19, 2017