How to Manage Pests

UC Pest Management Guidelines


Lygus Bugs

Scientific name: Lygus hesperus and others

(Reviewed 12/13, updated 12/13, corrected 9/16)

In this Guideline:

Description of the Pests

Adults are yellowish, brownish, or greenish bugs, about 0.3 inch (7–8 mm) in length, with a conspicuous triangle in the center of the back that is tinged brown, red, or yellow. Nymphs resemble adults, but are uniformly pale green with red-tipped antennae and have no wings. Lygus feed on the fruit or seeds of many flowering plants, including alfalfa and safflower. They can move to tomatoes when their primary hosts dry or are disturbed, such as when alfalfa is cut, safflower dries, or weedy fields of sugar beets are harvested.

For additional information on identifying lygus bugs, see A Field Key to the Most Common Lygus Species Found in Agronomic Crops of the Central San Joaquin Valley of California.


On the surface of the fruit, lygus bug damage is similar to that of stink bug damage immediately after feeding. The area below the feeding site, however, dries instead of becoming corky, causing the surface of the fruit to crack slightly. Therefore, damage is not as apparent. Lygus feeding has not been associated with the transmission of yeast pathogens like with stink bugs.


Treatment is not recommended for tomatoes to be used for paste or juice. However, if large numbers of lygus are present in fields intended for fresh market or whole pack processing, treatment may be warranted. Check with your processor regarding the significance of lygus damage to their product.

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 materials 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.
  (Beleaf 50SG) 2–2.8 oz 12 0
  COMMENTS: Research is lacking on the effectiveness on this insecticide in tomato, but it has proven to be effective against lygus bug in other crops such as cotton and strawberry and not as detrimental to natural enemies as other products.
  (Danitol 2.4EC) 10.66 fl oz 24 3
  COMMENTS: Do not use this product if leafminers are presentbecause it is destructive of their parasites.
  (Belay 50WDG) 1.6–2.1 fl oz 12 7
  COMMENTS: Apply as a foliar spray. Do not apply during bloom or if bees are actively foraging.
  (Lannate SP) 0.5–1 lb 48 1
  (Lannate LV) 1.5–3 pt 48 1
  COMMENTS: This material will also control armyworm and cabbage looper. Do not use if psyllids are in the field as carbamates tend to promote development of their populations; also if leafminers are present, it may cause outbreaks by destroying their natural enemies.
  (Dimethoate 2.67EC) 1.5 pt 48 7
  (Dimethoate 400) 1 pt 48 7
  COMMENTS: Do not use this product if leafminers are present because it is destructive of their parasites. Do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
** See label for dilution rates.
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 until harvest can take place. In some cases the REI exceeds the PHI The longer of these two intervals is the minimum time that must elapse before harvest may take place.
* 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).



[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Tomato
UC ANR Publication 3470

Insects and Mites

E. T. Natwick, UC Cooperative Extension, Imperial County
C. S. Stoddard, UC Cooperative Extension, Merced and Madera counties
F. G. Zalom, Entomology, UC Davis
J. T. Trumble, Entomology, UC Riverside
G. Miyao, UC Cooperative Extension, Solano and Yolo counties
J. J. Stapleton, UC IPM Program and Kearney Agricultural Center, Parlier (false chinch bug)
Acknowledgments for contributions to Insects and Mites:
C. G. Summers, Entomology, UC Davis and Kearney Agricultural Center, Parlier
C. F. Fouche, UC Cooperative Extension, San Joaquin County
N. C. Toscano, Entomology, UC Riverside

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