How to Manage Pests

UC Pest Management Guidelines



Scientific Name: Melanoplus spp.

(Reviewed 12/09, updated 12/09, pesticides updated 5/16)

In this Guideline:

Description of the Pest

Grasshoppers may occasionally attack cucurbit crops, particularly if planted adjacent to foothill rangeland. They normally migrate from the range into cultivated areas as vegetation on the rangeland dries up.


Grasshoppers destroy leaf tissue and, if present in extremely large numbers, will consume the entire plant. They may also chew on fruit, scarring the surface and netting of cantaloupes.


Keep fields and surrounding areas weed-free. Grasshopper problems usually occur when a migrating population from a foothill range area is attracted to the crop. Plant a trap crop between the crop and the direction that the grasshoppers might migrate from. The trap crop can be treated with cryolite, if allowed by the label. Treat the crop if feeding damage warrants control action.

Common name Amount per acre REI‡ PHI‡
(Example trade name)   (hours) (days)

Calculate impact of pesticide on air quality
Bee precaution pesticide ratings
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.
  (Sevin 5 bait) 20 lb 12 3
  COMMENTS: Apple pumice baits work better for crickets and grasshoppers than bran baits. Baits lose their attractiveness as they dry out. Apply in early evening to avoid drying out too soon from sun exposure. Use suitable ground or aircraft equipment that provides good distribution. Repeat application probably necessary.
  . . . or . . .
  (Sevin XLR Plus)* 0.5–1.5 pt 12 3
  COMMENTS: Observe plant response precautions listed on the label. Avoid excessive applications. Be certain spray volumes are appropriate to assure adequate coverage. Use low rate for nymphs and high rate for adults.
  (Warrior II with Zeon)* 1.28–1.92 fl oz 24 1
  (Asana XL) 5.8–9.6 oz 12 3
  COMMENTS: Repeat as necessary to maintain control. Do not exceed 0.25 lb a.i./acre per season.
  (Malathion 8-E) Label rates See label See 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.
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).
* Permit required from county agricultural commissioner for purchase or use.



[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Cucurbits
UC ANR Publication 3445

Insects and Mites

E. T. Natwick, UC Cooperative Extension, Imperial County
J. J. Stapleton, UC IPM Program, Kearney Agricultultural Center, Parlier
C. S. Stoddard, UC Cooperative Extension, Merced & Madera counties

Acknowledgment for contributions to Insects and Mites:
R. L. Coviello, UC Cooperative Extension, Fresno County
C. B. Fouche, UC Cooperative Extension, San Joaquin County
L. D. Godfrey, Entomology, UC Davis
J. B. LeBoeuf, AgiData Sensing, Inc., Fresno
M. Murray, UC Cooperative Extension, Colusa and Glenn counties
C. G. Summers, Entomology, UC Davis and Kearney Agricultural Center, Parlier

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