What damage do bagworms do? Bagworms will attack more than 120 different types of trees. ... But if they eat more than 80 percent of the tree, the entire evergreen may die. On deciduous trees (those that lose their leaves in winter), bagworms chew small holes in the leaves and can cause defoliation.

How long does it take for bagworms to kill a tree?

But within 2-3 weeks, they will die off as well leaving nothing but egg laden bags ready to re-infest your trees. If egg laying occurs early enough in summer, two generations of bagworms may cycle per season. In most areas, there is only time for one per year.

How do you treat bagworms in trees?

An insecticide with malathion, diazinon, or carbaryl (such as Ortho Tree & Shrub Insect Killer, available on Amazon) can rid you of a bagworm problem if applied to bushes and trees when the worms are still young larvae.