How to Manage Pests

UC Pest Management Guidelines


Tomato Fruitworm

Scientific name: Helicoverpa (=Heliothis) zea

(Reviewed 12/09, updated 11/12)

In this Guideline:


Tomato fruitworm adults are medium-sized moths with a wing span of about 1 to 1.3 inch (25-35 mm). They are pale tan to medium brown, or sometimes have a slight greenish tinge. The front wings are variously marked and usually have an obscure dark spot in the center and a lighter band inside a dark band around the tip. The hind wings are drab white and have a dark gray band around their tip. A diffuse light spot is in the center of the dark band.

At hatching, tomato fruitworm larvae are creamy white caterpillars with a black head and conspicuous black tubercles and hairs. Larger larvae vary in color from yellowish green to nearly black and develop fine white lines along the body but retain the black spots at the base of bristlelike hairs. Older larvae also have patches of stubby spines on their body segments that are much shorter than the bristles and can be seen best with the use of a hand lens.

Eggs are tiny, hemispherical, and slightly flattened on top with coarse striations or ribs running from base to tip. They are easy to confuse with looper eggs, but looper eggs have fine striations. Fruitworm eggs are laid singly on both upper and lower surfaces of the leaves usually in the upper part of the plant. When first laid they are creamy white, but develop a reddish brown ring after 24 hours.


Soon after hatching, the larvae burrow into the fruit, usually near the calyx, and remain inside, feeding on the flesh. Infested fruit decay, turn red, and fall off the plant early, reducing yield. Larvae consume very little foliage.


Regular monitoring of pepper fields is important in detecting and managing this pest. Weed control, site location, and biological control are important in reducing the potential for damage. Insecticide treatment may be necessary when monitoring indicates a need.

Cultural Control

These insects have a wide host range. Weed control in the area can help to reduce the population; however, the moths can fly great distances. Avoid planting peppers near field corn or garbanzo beans.

Biological Control

Tomato fruitworm eggs can be heavily parasitized by Trichogramma pretiosum. Experimental releases of Trichogramma have resulted in control of fruitworm on pole tomatoes. Parasitized eggs are completely black. When any eggs are found they should be held in vials for several days to determine the level of parasitism. The parasitic wasp, Hyposoter exiguae, attacks fruitworm larvae and can reduce fruitworm populations considerably; however, often the worm will die inside the fruit and the parasite cocoon remains in the fruit as a contaminant.

Organically Acceptable Methods

Cultural and biological control and sprays of Bacillus thuringiensis or the Entrust formulation of spinosad are acceptable for use in an organically certified crop.

Monitoring and Treatment Decisions

Start monitoring for tomato fruitworm at the seedling stage and continue through harvest. Inspect the upper part of the plants for fruitworm eggs. Examine the eggs closely with a hand lens to determine the stage of development of the larvae and check for parasitism. If necessary, treat within 2 to 3 days after the head capsule has formed. There are no treatment thresholds.

Timing of sprays is critical because the worms enter the fruit shortly after hatching and are thus susceptible to the pesticide for only a brief period. In peppers grown for fresh market consumption and where fruit aesthetics are paramount, treatments may be needed when egg laying is documented.

Common name Amount per acre** R.E.I.+ P.H.I.+
(trade name)   (hours) (days)

Calculate impact of pesticide on air quality
The following materials are listed in order of usefulness in an IPM program. When choosing a pesticide, consider information relating to impact on natural enemies and pollinators and environmental impact. Not all registered pesticides are listed. Always read the label of the product being used.
  (Radiant SC) 5-10 fl oz 4 1
  (Entrust)# 1-2 oz 4 1
  (Success) 3-6 oz 4 1
  COMMENTS: Use higher rate for larger worms and heavy infestations. Best control is achieved when aimed at newly hatched larvae and coverage is thorough. More broad-spectrum than Bt but has very low toxicity to humans, vertebrates, and the adults of many natural enemies. Can remain toxic to larval stages (especially syrphid fly) for 5-7 days after treatment. Do not exceed 29 fl oz of Success or 9 oz of Entrust/acre per crop.
  (Intrepid 2F) 10-16 fl oz 4 1
  COMMENTS: An insect growth regulator. Apply at the beginning of egg hatch. Pheromone traps can be used to detect moth flight. When traps indicate a flight is occurring, monitor plants for eggs and treat when they appear. Do not apply more than 16 fl oz/acre per application or 64 fl oz/acre per season.
  (Coragen) 3.5-5 fl oz 4 1
  COMMENTS: May be applied as either a foliar spray or via drip irrigation.
  (various products) Label rates 4 0
  COMMENTS: Must be consumed by the larva to be effective. Coverage is critical for controlling this pest, especially between and under leaves and where leaves touch the fruit.
  (Avaunt) 3.5 oz 12 3
  COMMENTS: Minimum interval between sprays is 5 days. Do not apply more than 14 oz/acre per crop.
  (Asana XL) 5.8-9.6 fl oz 12 7
  COMMENTS: Do not apply more than 0.35 lbs a.i./acre per season. If leafminers are present in the pepper crop, limit use of this product to late in the season to minimize negative impacts on biological control.
  (Lannate SP) 0.25-0.5 lb 48 3
  (Lannate LV) 0.75-1.5 pt 48 3
  COMMNENTS: Do not use if psyllids are present.
** See label for dilution rates.
+ 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.
# 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: Peppers
UC ANR Publication 3460

Insects and Mites

E. T. Natwick, UC Cooperative Extension, Imperial County
J. T. Trumble, Entomology, UC Riverside
Jose Aguiar, UC Cooperative Extension, Riverside County
Acknowledgment for contributions to Insects and Mites:
W. J. Bentley, UC IPM Program, Kearney Agricultural Center, Parlier
R. L. Coviello, UC Cooperative Extension, Fresno County
C. G. Summers, Kearney Agricultural Center, Parlier
W. E. Chaney, UC Cooperative Extension, Monterey County
C. F. Fouche, UC Cooperative Extension, San Joaquin County

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