Bad Bugs Bagged

Made the rounds and found many bagworms on the red pines in the back yard. These are insect pests that you pick off by hand.

In years past I have found them on the sweet gum trees, but this year they have favored the spruce and pines. Most seem within arm’s reach and they tend to be on the leeward side of the trees on my windy plat. Check your plants to see if you have any. I remove them and burn them.

The first photo is a normal pine shoot and budding cones. The second picture shows the bagworm and their nefarious natural disguise.

Advice from experts?

pick them off and that will actually help reduce the population,” Smith said. “The insect is protected by that bag so there’s no point in spraying.”

Roberts recommends putting the bagworms in kerosene or diesel fuel. She cited an instance in which a woman picked the bags and then put them in a garbage can in her garage. The next morning, all of the worms had escaped and taken over the garage ceiling. Boyd suggests simply putting the insects in a tightly sealed bag before disposing of it.

Other ways to rid them from your plants?

Now there is hope of deterring the bagworm pest altogether. New studies at the University of Illinois at Urbana-Champaign show promise that planting members of the Aster family near and/or around the susceptible tree will attract a natural predator of bagworm, ichneumonid wasps.

Their life cycle is described by KSU.edu (pdf file):

Bagworms overwinter as eggs deposited in female pupal
cases, which are individually housed within spindle-shaped
female bags. Generally, from about mid-May through the end of
June, larvae hatch from eggs and exit from the posterior opening
of old bags. Individual larvae often drop down from the bag on
a fine silk. Swinging in the breeze, they come into contact with
limbs or foliage and immediately construct miniature silk-lined
bags. Only after the bags have been completed do the larvae
begin feeding. They decorate their bags with bits and pieces
of whatever foliage they are consuming. As larvae grow, bags
increase in size to accommodate them. (Figure 2)
Larvae remain in their bags as they feed and move about.
Only their heads and thoracic (legged) segments protrude from
the bag’s anterior opening when they molt. At this time larvae
temporarily close off the anterior opening. After molting, lar-
vae reopen their bags and continue to forage. The posterior of
the bags is always open, providing an exit through which fecal
materials and shed skins can be eliminated.
By mid- to late-August feeding is complete. Larvae firmly
anchor their bags to the twigs and branches on which they were
feeding, sealing the anterior ends of their bags. Within the bags,
the larvae turn with heads facing downwards near the posterior
opening of their bags and enter the pupal stage.
Pupation is completed in
two to three weeks.

Penn State Factsheet
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