Yale Park Homeowners Association News and Information from the
Yale Park Homeowners Association
Yale Park Homeowners Association

Texas AgriLife Extension Service

Kimberly Schofield
Program Specialist-Urban IPM

Watch Out for Spring Cankerworms

The spring cankerworm, Paleacrata vernata (Peck), is in the family Geometridae.  They are often called inchworms, since they move by forming a loop with the middle part of the body and then extend the front part of the body straight out.  They are also about an inch in length and have longitudinal stripes of green, brown and yellow that allows for them to easily blend in with tree branches.  They also have two pairs of prolegs on their abdomens.

Spring cankerworms overwinter as pupae and emerge as moths in the early spring.  After adults emerge, wingless females crawl up the tree trunks and onto the branches where they deposit eggs in clusters on the truck.  The eggs hatch in the spring and the caterpillars feed for about 3 or 4 weeks before they drop to the ground to pupate in the soil.  They are commonly a nuisance when they drop to the ground because they leave silk threads trailing from the trees.  Also the caterpillars may be blown by the wind into new locations when they are suspended on silken threads.  Cankerworms remain in the soil to pupate and then emerge as adults the next spring.  Adults are grey and green colored moths.  The males are small with an inch wingspan, but the females are wingless.

Many fruit and shade trees are attacked by cankerworms, where they skeletonize the leaves.  Cankerworms can be a nuisance when in large populations, which can cause complete defoliation of trees.

Some Control Options:

Large and healthy trees can withstand total defoliation without significant damage, so control is not necessary.  However, control is suggested for new transplants, specimen trees or fruit and nut bearing trees.  Also control is needed if a tree has had a previous defoliation or other problems such as drought or disease.  Oak and elm trees are more commonly attacked.

When control is needed, the insecticide should be timed to kill early stages of the caterpillar.  Insecticides containing such chemicals as carbaryl, acephate, or Bacillus thuringiensis can be used to control cankerworms.

Spring cankerworm
Spring cankerworm.
Photo by Texas A&M University.


Mention of commercial products is for educational purposes only and does not represent endorsement by Texas AgriLife Extension or The Texas A&M University System.  Insecticide label registrations are subject to change, and changes may have occurred since this publication was printed.  The pesticide user is always responsible for applying products in accordance with label directions.  Always read and carefully follow the instructions on the container label.

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