Bagworms: don't let them bag your nursery stock

From MSU Extension:

Bagworms, Thyridopteryx ephemeraeformis (Haworth), is an insect pest that can cause defoliation to conifers like arborvitae, juniper, pine, spruce as well as many deciduous plants such as black locust, Norway maple and many shrubs. Most often, we think of this pest as a problem in southern states east of the Mississippi River. However, in recent years more reports of damage and defoliation from bagworms have been noted in states like Indiana and Ohio. It has been observed in southern Michigan on occasion and even known to cause damage to wild huckleberry in Michigan’s Upper Peninsula, probably overwintering extremely well under the abundant snow cover.

Female bagworms lay from 500-1,000 eggs each year in the fall before they die. Eggs will hatch in the spring months of May and June. After emerging, the young larvae can “balloon down” on silken threads to other portions of an infested plant or can blow around on winds to other plants. This is a similar habit to the “ballooning” that young gypsy moth larvae do.

Once the larvae land on a plant, they will spin a bag of silk and plant debris. They live in this structure, which may look like an upside down ice cream cone as described by some entomologists. The larvae feed and continue to grow and the bag grows in size, firmly attached to a twig on the plant. Bagworms feed for six to eight weeks and if numbers are high enough on a conifer, they can strip all the needles or devour all the leaves off a deciduous plant.

Click here to read more.