How to Manage Pests

UC Pest Management Guidelines

Citrus

Leaffooted Bug

Scientific Name: Leptoglossus zonatus

(Reviewed 2/17, updated 2/17)

In this Guideline:


Description of the pest

The leaffooted bug gets its name from the small spined leaflike enlargements found on the hind legs of large nymphs and adults. Adult bugs are about 1 inch long and have a narrow brown body with a yellow or white zigzag line across their flattened back and two yellow spots on the pronotum, the platelike structure just behind the head.

Leaffooted bugs have two to three generations per year and prefer to feed on seeds of crops like almond in the spring, pistachio in the summer, and pomegranate in the fall. In the late fall leaffooted bugs seek out protected areas, such as citrus trees or the spaces between palm fronds, to overwinter as adults in aggregations. They remain in these aggregations until the following spring and disperse into other crops from late March through May.

Damage

The leaffooted bug is an occasional pest of citrus in the San Joaquin Valley and usually only occurs in groves that are adjacent to preferred summer and fall hosts like pistachio and pomegranate. Leaffooted bugs can cause damage to mature citrus fruit in the winter and early spring, and to young fruit if the bugs are still present after bloom.

Leaffooted bugs feed by inserting their large proboscis (mouthparts) into fruits and nuts in search of seeds. In citrus, where seeds are typically lacking, bugs probe through the rind multiple times and feed on juice. On large fruit, probing does not cause any visible external damage on the rind, but can cause significant damage internally when juice sacs are punctured and desiccate. On small fruit, the area around the penetration site becomes slightly sunken and discolored as the fruit expands over time.

MANAGEMENT

Treatment thresholds for this pest have not been developed for any crop, including citrus. Citrus growers in the lower San Joaquin Valley that are near nut crops or pomegranate orchards should monitor groves for overwintering aggregations of adults between November and March.

  1. Look for aggregations of adult bugs on the fruit.
  2. If bugs are found, look for puddles of dark amber-colored excrement on the surface of the fruit (indicating that the bugs are feeding) and cross-section the fruit to look for internal damage.
  3. If bugs are feeding and damage is occurring, consider making an insecticide application.
  4. If aggregations are found after harvest is completed, mark them for future monitoring. In many cases overwintering bugs will die due to cold temperatures, and in other cases the bugs will disperse and fly out of the orchard before small fruit are available after bloom.

In the unlikely event that aggregations are still found in the orchard in April and May, and small fruit are present, an insecticide application may be warranted.

The only insecticides known to have long-term efficacy on leaffooted bugs are pyrethroids and organophosphates. However, use these products cautiously (e.g. spot treat or use rates that minimize harm to natural enemies), as they have broad-spectrum effects on natural enemies and pollinators.

There are no cultural controls available for leaffooted bug. The only biological control is an egg parasitoid, Gyron spp., that is unable to attack the adult stage of leaffooted bug that is present during the winter in citrus.

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.
 
A. FENPROPATHRIN*
  (Danitol 2.4EC) 16–21.33 fl oz 24 1
  MODE-OF-ACTION GROUP NUMBER1: 3A
  COMMENTS: Can cause secondary pest outbreaks, especially spider mites. Toxic to pollinators, do not use when bees are present.
 
B. BETA-CYFLUTHRIN
  (Baythroid XL)* 2.4–6.4 fl oz 12 0
  MODE-OF-ACTION GROUP NUMBER1: 3A
  COMMENTS: Can cause secondary pest outbreaks, especially spider mites. Toxic to pollinators, do not use when bees are present.
 
C. CHLORPYRIFOS*
  (Lorsban Advanced) 2–7 pt 120 (5 days) 21
  MODE-OF-ACTION GROUP NUMBER1: 1B
  COMMENTS: Avoid drift or tailwater runoff into surface waters. Certain formulations emit high amounts of volatile organic compounds (VOCs); use low-VOC formulations. Regulations affect use for the San Joaquin Valley from May 1 to October 31, 2017. Review the Department of Pesticide Regulation's updated fact sheet. Toxic to pollinators; do not use when bees are present.
 
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 these two intervals is the minimum time that must elapse before harvest may occur.
* 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).

IMPORTANT LINKS

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Citrus
UC ANR Publication 3441

Insects, Mites, and Snails

E. E. Grafton-Cardwell, Lindcove Research and Extension Center, Exeter and Entomology, UC Riverside
J. G. Morse, Entomology, UC Riverside
D. R. Haviland, UC Cooperative Extension, Kern County and UC IPM Program
B. A. Faber, UC Cooperative Extension, Santa Barbara and Ventura counties

Acknowledgments for contributions to Insect, Mite, and Snails:
J. Barcinas, E.S.I., Corona, CA
R. Dunn, Badger Farming Co., Exeter, CA
J. Gorden, Pest Management Associates, Exeter, CA
C. E. Kallsen, UC Cooperative Extension, Kern County
D. Machlitt, Consulting Entomology Services, Moorpark, CA
C. Musgrove, retired entomologist, Riverside, CA
K. Olsen, S & J Ranch, Pinedale, CA
N. V. O'Connell, UC Cooperative Extension, Tulare County
P. A. Phillips, UC IPM Program, UC Cooperative Extension, Ventura County
T. Roberts, E.S.I., Corona, CA
T. Shea, UC Cooperative Extension, Riverside County
J. Stewart, Pest Management Associates, Exeter, CA
P. Washburn, Washburn & Sons Citrus Pest Control, Riverside, CA

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