How to Manage Pests

UC Pest Management Guidelines


Sap Beetles

Scientific Name: Glischrochilus quadrisignatus, Glischrochilus fasciatus

(Reviewed 12/09, updated 12/09)

In this Guideline:

Description of the Pests

Also known as picnic beetles, adult sap beetles are about ¼ inch (6.5 mm) in length, shiny black, and have four yellow-to-orange spots on the back of each wing cover. The tips of the antennae of both species are distinctively knobbed.

Sap beetles overwinter as adults in decomposing organic matter and emerge to resume feeding after a warming trend of temperatures over 68°F. While there is only generation of sap beetles per year, populations tend to peak by midsummer. Adults bore into caneberry fruit and can be contaminants in harvested fruit. Larvae, which are not often found on the inside of fruit, are about the same length as adults, with a brown head capsule.


Adult beetles bore into ripe to overripe fruit to feed and are often found around the receptacle. The feeding, while quite damaging, also can create entry pathways for fungi and bacteria, resulting in increased incidence of fruit rots.


Chemical control of sap beetles in caneberry fruit is very difficult, because applications to ripe fruit not only take place necessarily close to harvest, but also the beetles are inside the fruit, making them almost impossible to reach with conventional topical pesticide applications.

Biological Control

There is no commercially acceptable biological control for sap beetles in the field at this time.

Cultural Control

Sanitation in the field is probably the most powerful tool growers have in managing infestations of sap beetles. As damaged or overripe, rotten, and fermenting fruit are very attractive to sap beetles, the removal of this fruit will result in a reduction of sap beetles. Harvest fruit promptly as it ripens to eliminate both the odor and availability of susceptible fruits. Covering fruit on picking and removing it from the field as soon as possible will prevent contamination of fruit after harvest.

Organically Acceptable Methods

Cultural controls are organically acceptable.


[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Caneberries
UC ANR Publication 3437

Insects and Mites

M. P. Bolda, UC Cooperative Extension, Santa Cruz County
L. J. Bettiga, UC Cooperative Extension, Monterey County

Acknowledgment for contributions to Insects and Mites:
E. Show, Driscoll Strawberry Associates Inc., Watsonville, CA
E. J. Perry, UC Cooperative Extension, Stanislaus County

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.