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How to Manage Pests

UC Pest Management Guidelines

| More pests | More crops | About guidelines |

Squash bug adults mating.

Cucurbits

Squash Bug

Scientific Name: Anasa tristis

(Reviewed 11/05, updated 6/08)

In this Guideline:

DESCRIPTION OF THE PEST

The adult squash bug is 0.65 inch (1.5 cm) in length. It is brownish yellow but appears black because of a dense covering of black hairs. Protruding margins of the abdomen are orange or orange and brown striped, and the margins of the pronotum are yellow. Shiny, eliptical reddish brown eggs are laid singly or in groups of 15 to 40 on the underside of leaves or on stems. Young nymphs are pale green, while later instars have a blackish thorax and brownish abdomen; they are often covered with white powder.

DAMAGE

Young nymphs feed in clusters. Their feeding causes the affected part of leaves to droop, turn black, and dry out. Young plants can be killed. Squash bugs are particularly damaging to squash and pumpkins but can also be serious on young melons, especially watermelon.

MANAGEMENT

Good field sanitation and other cultural practices help to prevent damage by this pest. Treatments may be warranted if the insect is causing damage in the field.

Cultural Control
Destroy crop residues and reduce overwintering hiding places. Row covers applied at planting and removed at first bloom exclude squash bugs. Some plant varietal preferences occur: pumpkins, watermelons and squash are the most seriously damaged; zucchinis are less susceptible.

Organically Acceptable Methods
Cultural controls are acceptable to use in an organically certified crop.

Monitoring and Treatment Decisions
If the insect is present, treat at the early seedling stage. At later growth stages, treat only if squash bugs are present in high numbers. Squash bugs are very difficult to control so good coverage is critical.

Common name Amount/Acre R.E.I.+ P.H.I.+
(trade name)   (hours) (days)
When choosing a pesticide, consider information relating to water quality and impact on natural enemies and honey bees.
 
A. ESFENVALERATE*
  (Asana XL) 5.8–9.6 oz 12 3
  MODE OF ACTION GROUP NUMBER1: 3
  COMMENTS: Repeat as necessary to maintain control. Do not exceed 0.25 lb a.i./acre/season. May encourage the buildup of pest mite populations. Highly toxic to honey bees.
 
B. ENDOSULFAN*
  (Thionex) 3EC 0.66–1.33 qt 24 2
  (Thionex) 50WP 1–2 lb 24 2
  MODE OF ACTION GROUP NUMBER1: 2A
  COMMENTS: Do not exceed 3 applications/year. See label for restrictions on use. Moderately toxic to honey bees.
 
+ Restricted entry interval (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (P.H.I.) 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.
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 http://www.irac-online.org/.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Cucurbits
UC ANR Publication 3445
Insects and Mites
E. T. Natwick, UC Cooperative Extension, Imperial County
L. D. Godfrey, Entomology, UC Davis
C. G. Summers, Entomology, UC Davis/Kearney Agricultural Center, Parlier
J. J. Stapleton, UC IPM Program, Kearney Agricultultural Center, Parlier
Acknowledgment for contributions to Insects and Mites:
R. L. Coviello, UC Cooperative Extension, Fresno County
C. B. Fouche, UC Cooperative Extension, San Joaquin County
J. B. LeBoeuf, AgriData Sensing, Inc., Fresno
M. Murray, UC Cooperative Extension, Colusa/Glenn counties

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Statewide IPM Program, Agriculture and Natural Resources, University of California
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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 How to manage pests, or in the U.S., contact your local Cooperative Extension office for assistance. /PMG/r116301111.html revised: June 30, 2008. Contact webmaster.