Spring cankerworm 2000 Spring Cankerworms on the March Spring cankerworms at Arbor Hills Nature Preserve, March 25, 2001. If you were out for a walk this past weekend you may have noticed millions of tiny caterpillars hanging from tree branches and blowing on the wind. Known as spring cankerworms, these insects can be important defoliators of trees in east and central Texas, especially. While the jury's still out on whether there will be a full-blown cankerworm infestation in east Texas this year, at least one entomologist has been predicting troubles. Considering this winter was cold by our standards, cankerworms are likely to be more of a problem this year.
Cankerworms belong to the moth family Geometridae, also known as inchworms for their looping walk.
Larvae hatch from their egg masses in the spring when trees are reaching bud break. The larvae grow to about one inch long and are quite slender with light green stripe along their sides. When not walking, the caterpillar's drab color blends in well with the twigs on which they rest. Larvae typically feed for 3 to 4 weeks before dropping to the ground to pupate. Fortunately, there is only one generation a year, so this does not mean gardeners will be battling caterpillars all season long.