How to Manage Pests

UC Pest Management Guidelines


Cherry Slug

Scientific Name: Caliroa cerasi

(Reviewed 11/09, updated 11/09, pesticides updated 9/15)

In this Guideline:

Description of the Pest

Adults are small, glossy black sawflies about 0.2 inch long. The newly hatched larvae are white with a yellowish brown head. Almost immediately after hatching, the larva exudes an olive green coating that covers its body and gives it the appearance of a slug. The head end is wider than the rest of the body and a fully mature larva is about 0.5 inch long. Cherry slugs overwinter as pupae in the soil. There are two generations a year with adults emerging in July to lay eggs of the next generation that overwinters.


Cherry slugs are a pest of cherries in coastal areas. Larvae skeletonize leaves and may remove all tissue except for the fine network of veins. High populations may reduce fruit size.


Inspect foliage in spring, and treat if high numbers are found.

Common name Amount to use** REI‡ PHI‡
(Example trade name) (conc.) (dilute)
(hours) (days)

Calculate impact of pesticide on air quality
The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least harmful to natural enemies, honey bees, and the environment are at the top of the table. When choosing a pesticide, consider information relating to air and water quality, resistance management, and the pesticide's properties and application timing. Not all registered pesticides are listed. Always read the label of the product being used.
  (Entrust)# 1.25–2.5 oz 0.42–0.83 oz 4 7
  COMMENTS: Toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
  (Delegate WG) 4.5 oz/acre 4 7
  COMMENTS: Toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
  (Diazinon 50W) 1 lb/ 100 gal water 96 (4 days) 21
  COMMENTS: Avoid drift and tailwater runoff into surface waters. Where cherries are grown adjacent to waterways, do not use this material. Highly toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
** For concentrate applications, use the amount given in 80–100 gal water/acre, or lower if the label allows; for dilute applications, amount is per 100 gal water to be applied in 300–400 gal water/acre, according to label.
Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (PHI) is the number of days from treatment to harvest. In some cases the REI exceeds the PHI. The longer of two intervals is the minimum time that must elapse before harvest.
* Permit required from county agricultural commissioner for purchase or use.
# Acceptable for use on organically grown produce.
1 Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode-of-action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at



[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Cherry
UC ANR Publication 3440

Insects and Mites

J. A. Grant, UC Cooperative Extension, San Joaquin County
J. L. Caprile, UC Cooperative Extension, Contra Costa County
W. W. Coates, UC Cooperative Extension, San Benito County
R. A. Van Steenwyk, Insect Biology, UC Berkeley
K. M. Daane, Kearney Agricultural Center, Parlier

Acknowledgment for contributions to Insects and Mites:
J. Colyn, Mid-Valley Ag. Services
M. Devencenzi, Devencenzi Ag. Pest Mgmt. and Research
P. McKenzie, Mid-Valley Ag. Services

Top of page

Statewide IPM Program, Agriculture and Natural Resources, University of California
All contents copyright © 2015 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   /PMG/r105301911.html revised: September 29, 2015. Contact webmaster.