Bagworm – On Leyland Cypress

Q: I have four Leyland cypress trees that are six feet tall. They all have little pods, containing some sort of worm, hanging from almost every branch.  One of the trees died and the others aren’t looking too good. What should I do now?

A: Junipers, Leyland cypress and cedar trees can be skeletonized by August if they have bagworms.

Examination of a rapidly disappearing shrub reveals dozens of brown “bags” hanging from the limbs. The bags are made from the plant’s needles. They contain a wingless moth, who feasts on the plant’s greenery.

Unfortunately, once the bag is easily noticeable, it is too late to control the pest with insecticides.

At this point, there is no solution except hand removal. Wear a long sleeved shirt to avoid being scratched by the needles and scales of the host plant.

Collect and destroy all cocoons. Despite their empty appearance, there are likely to be eggs in the bottom tip of the bag.

Make a note to spray Bacillus thuringiensis (click for sources) or a landscape insecticide three times at weekly intervals in mid-May, when the caterpillars have not yet formed their protective bags.