Insect Hotline Issue 12


Bagworms in the “dunce cap” stage.  B. t. and Conserve provide good control at this stage.


Bagworm infestation with bags already drooping down.


Damage from bagworm feeding (Photo by: T. Simms).

ab4 ab5

Bag with green foliage incorporated into it suggests a live caterpillar inside the bag.  Insect growth regulators (Dimilin or Confirm), Acelepryn, Conserve (depending on bag/caterpillar size and population density) pyrethroids, acephate or carbaryl provide good control against larger caterpillars.  Caterpillar feeding is usually finished by mid-August, consequently hand picking in September – May is a good method to reduce next season’s populations.  Photos provided by:  Brian Kunkel, University of Delaware

Issue 10: Hot in May

aphids on tulip popular

Aphids are feeding and reproducing on many plants at this time of the year.  The picture is of aphids feeding on tulip popular.  Honeydew falling onto furniture, structures, vehicles, other plants and walkways can be a nuisance issue.  These usually require no control efforts.

dunces in May

Some bagworm eggs have hatched and larvae have ballooned to nearby hosts.  Look closely for the ‘dunce cap’ stage of these caterpillars feeding on trees and shrubs.  Applications of Bt now through late June will provide excellent control of these small caterpillars.


pine spittle bug

Pine spittle bug requires no control efforts.  They are just unsightly.

rose slug sawfly damage


Roseslug sawflies are feeding on roses at this time.  Early instars cause ‘window paning’ damage to leaves.  Eventually the remaining dermal tissue of the leaf dries out and falls off the leaf leaving behind a smooth-edged hole in the leaf.

sweek mock orange

Sweet Mockorgange is in bloom to full bloom in Sussex county.  As the sign indicates (from the education gardens) the arborvitae leafminer adult is flying and tussock moth caterpillars are feeding.

All pictures provided by Tracy Wooten, University of Delaware