An Ashland reader recently noticed some curious little, almost lantern-like attachment appearing on her spruce.
At first glance, these little cocoons looked like little lanterns in her evergreen. These clear wing moths infested many of her spruce trees and potentially there are 130 other plants.
When you first look at these cocoons, you may think that you are looking at a small branch with a swelling problem or a pine cone.
If you have several spruces or noticed odd cocoons on your Christmas tree, bagworms might be the culprit. My reader diligently picked off the cocoons by hand, hoping to rid her trees of the infestation.
Let’s explore what bagworms are and the best ways to deal with them.
Bagworm or Thyridopteryx ephemeraeformis is a clear-winged moth that spins its cocoon with bits and pieces of plant material that cleverly camouflaging the cocoon to look like a branch on the tree.
Each case grows from one and a half to two inches. The caterpillars start out black and turn brown. Males look a lot like bees; they have black furry bodies and clear wings. Females look like maggots, have yellowish-white soft bodies, no mouth parts, no legs, no antennae, no eyes, and have tufts of hair near the end of the body.
When fertilized, the female lays 1000 eggs. Eggs are cream-colored and tiny.
Each bagworm in Ohio completes its life cycle in 2 years. The eggs and caterpillars share the cocoon.
One good thing I can tell you about the bagworm’s life cycle is that you only have one set of eggs per year. Caterpillars start their work after they hatch and break their dormancy in late spring.
These caterpillars begin constructing their case immediately, starting on the surface of the leaf and gradually migrating to the bottom of the leaf and even further, and the bag gets larger.
As these little caterpillars feed on the leaves, their habits are like those of leaf miners. This stage of the insect’s life cycle is the most damaging to the tree and can “skeletonize” the leaves in the near proximity to the caterpillar.
There are other levels of infestation where you may find what looks like dunce caps in the plants. With large infestations, the trees can truly suffer. In late summer, the caterpillars enter their dormancy and the cocoon.
Reproduction of adult males and females occurs in September during normal years,\ meaning mating and egg- laying occur during this month.
Drought years’ things can change.
Among the natural enemies are the ichneumonid wasps which use this caterpillar to help hatch their babies, which are laid on the caterpillar’s body. Woodpeckers, Sapsuckers, Hornets, and Vespid Wasps eat these insects for their meals.
You can purchase ichneumonid wasps and other predatory insects in catalogues.
The first control for this insect pest is removing the bags by hand during the winter and burning them. Pheromone traps can attract these moths and control them. A variety of insecticides can be used, but only after the eggs hatch.
One of my favorite natural controls is Bt (Bacillus thuringiensis), also known as Dipel. Sevin can also be used to control this moth if applied early in the season before they get large.
Permethrin or Eight, bifenthrin, and cyfluthrin can also be used to control this insect, but they are also applied early in the season, which may pose challenges.
Organic oils, such as clove oil, cinnamon oil, and others, may also be used successfully. As the females hatch from their cocoons, they have no mouthparts, which makes it difficult for the oil to enter their bodies.
However, with this oil sprayed on them, they may have a harder time surviving.
Spinosad and Neem oil can also be used to control these insects at the correct time. Spinosad is a broad-spectrum insecticide that may damage your plants. August applications of these chemicals become ineffective.
Be careful when spraying inside the trees, as the canopies and leaves can be dense, blocking the spray from reaching the interior bagworms. I would also think that a good coating of Tangle Foot six inches above ground level would control many of the caterpillars earlier in the year.
Time the use of these compounds appropriately for the best results.
Bagworms can be a nuisance, but with timely action and the right control method, you can protect your spruces and other evergreens from serious damage. Remember to check your trees regularly, especially before bringing a Christmas tree indoors!
Have a nice stroll in your garden this week. If you have questions, drop an email to ericlarson546@yahoo.com.