How to Manage Pests

UC Pest Management Guidelines

Larva of fall cankerworm, Alsophila pometaria.


Pear Cankerworms

Scientific names:
Spring cankerworm: Paleacrita vernata
Fall cankerworm: Alsophila pometaria

(Reviewed 11/12 , updated 11/12 )

In this Guideline:


Spring and fall cankerworms were once major pests of pears when codling moth was controlled with lead arsenate. When organophosphates were used to control codling moth, they ceased to be a problem. The larvae are typical of the group of worms called inch or measuring worms. When mature they are about 1 inch long, green to olive green, with stripes of a different shade of green along the sides.


The larvae are primarily leaf feeders, tending to skeletonize leaves. Occasionally they feed on young fruit by biting deep holes, which later heal, but leave large, scarred depressions similar to the injury caused by green fruitworms. Larvae can be found feeding throughout the tree but tend to be more numerous along center scaffold limbs.


Cankerworms are potential threats in pear orchards where selective materials are used for codling moth control. They may be observed in spring when monitoring for leafrollers during bloom (see SAMPLING AT BLOOM). Follow treatment guidelines for obliquebanded leafroller or omnivorous leafroller.


[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Pear
UC ANR Publication 3455

Insects and Mites

L. G. Varela, UC IPM Program, UC Cooperative Extension, Sonoma County
R. B. Elkins, UC Cooperative Extension, Lake County
R. A. Van Steenwyk, Insect Biology, UC Berkeley
C. Ingels, UC Cooperative Extension, Sacramento County
Acknowledgment for contributions to Insects and Mites:
C. Pickel, UC IPM Program, UC Cooperative Extension, Sutter/Yuba counties
P. W. Weddle, Weddle, Hansen & Associates
R. Hansen, Weddle, Hansen & Associates
P. Chevalier, United Ag Products, Ukiah
M. Hooper, Ag Unlimited, Lakeport
B. Knispel, Pest Control Adviser, Upper Lake
T. Lidyoff, Purity Products, Healdsburg
G. McCosker, Harvey Lyman Agservices, Walnut Grove
B. Oldham, Ag Unlimited, Ukiah
J. Sisevich, AgroTech, Kelseyville (retired)
D. Smith, Western Farm Service, Walnut Grove
B. Zoller, The Pear Doctor, Inc., Kelseyville

Top of page

Statewide IPM Program, Agriculture and Natural Resources, University of California
All contents copyright © 2017 The Regents of the University of California. All rights reserved.

For noncommercial purposes only, any Web site may link directly to this page. FOR ALL OTHER USES or more information, read Legal Notices. Unfortunately, we cannot provide individual solutions to specific pest problems. See our Home page, or in the U.S., contact your local Cooperative Extension office for assistance.

Agriculture and Natural Resources, University of California

Accessibility   Contact webmaster.