How to Manage Pests

UC Pest Management Guidelines

Citrus

Katydids

Scientific Names:
Forktailed bush katydid: Scudderia furcata
Angularwinged katydid: Microcentrum retinerve

(Reviewed 9/08, updated 6/13)

In this Guideline:


Description of the Pest

Katydids resemble grasshoppers but have long antennae. Nymphs are wingless and have black and white banded antennae. Females of the forktailed katydid lay gray, oval, flat eggs in leaves where they have been feeding. Nymphs appear in April and May and take 2 to 3 months to mature. Angularwinged katydids are larger than forktailed katydids, have broader wings and have a humpback appearance both as nymphs and as adults. Females lay their gray, oval eggs in two overlapping rows on twigs and leaves. Katydids have only one generation a year.

Damage

Of the two species feeding on citrus, only the forktailed katydid causes economic damage. This species feeds on young fruit at petal fall with subsequent buildup of scar tissue and distortion of expanding fruit. Katydids take a single bite from a fruit and then move to another feeding site on the same or nearby fruit. In this way, a few katydids can damage a large quantity of fruit in a short time. They also eat holes in leaves and maturing fruit, creating injury that resembles damage by citrus cutworm. The angularwinged katydid is less abundant than the forktailed katydid and feeds only on leaves.

Management

With the reduced use of organophosphate and carbamate insecticides, katydids have become more numerous. Larger instars are not well controlled by cryolite or spinosad.

Biological Control

A number of parasitic wasps will attack katydid eggs, however, they are generally not effective enough to prevent damaging levels from developing.

Organically Acceptable Methods

Biological control and the Entrust formulation of spinosad are organically acceptable methods.

Monitoring and Treatment Decisions

Monitor for katydids starting in April. Before petal fall, they will be feeding on the newly expanding leaf flush. A timed search (3 minutes per tree) of 20 trees can be used to estimate their numbers. Approach the tree slowly, because katydids have excellent eyesight and will hide behind leaves if they see you coming. Look for damaged leaves, and search the foliage around the damaged area for katydids. There is no treatment threshold for katydids; however, if you detect leaf feeding and can find one or more per tree in a timed search then it is probably time to treat.

If treatments of diflubenzuron (Micromite) or cryolite are planned, put them on before petal fall because they are slow acting. Micromite does not kill the katydid until it tries to molt (10 days) and cryolite is a stomach poison that slowly kills the katydid over several days.

After petal fall, katydids can do a lot of damage in a short amount of time, so killing them quickly is important. If they are found at this time, many growers add a low rate of chlorpyrifos or a low rate of a pyrethroid to the citrus thrips spinosad treatment. The reduced rate of the organophosphate or pyrethroid helps to preserve natural enemies needed for other pests.

Common name Amount to use R.E.I.‡ P.H.I.‡
(example trade name) (type of coverage)** (hours) (days)

  Calculate impact of pesticide on air quality
 
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. CRYOLITE
  (Prokil Cryolite 96) 8–20 lb/acre (OC) 12 15
  (Kryocide) 8–20 lb/acre (OC) 12 15
  RANGE OF ACTIVITY: Pests: intermediate (foliage feeders such as worms, katydids, and Fuller rose beetle); Natural enemies: few, if any
  PERSISTENCE: Pests: long, unless washed off by rain; Natural enemies: none to short
  MODE OF ACTION GROUP NUMBER1: unknown
  COMMENTS: Check label for variety. Use higher rate for larger trees. Slow-acting stomach poison that may take several days of warm weather to kill katydids.
 
B. DIFLUBENZURON*
  (Micromite 80WGS) 3.125–6.25 oz/acre (OC) 12 21
  RANGE OF ACTIVITY: Pests: intermediate (katydids, peelminer, leafminer, grasshoppers); Natural enemies: predatory beetles
  PERSISTENCE: Pests: intermediate; Natural enemies: intermediate
  MODE OF ACTION GROUP NUMBER1: 15
  COMMENTS: Can be used during bloom. Timing treatments for peaks in moth flights is important because it only kills the egg stage of the peelminer. Apply by ground application using 50 to 200 gallons of water per acre. Do not apply within 25 feet of bodies of water. Use allowed under a FIFRA 2(ee) recommendation.
 
C. NALED
  (Dibrom 8 Emulsive) 1–2 pt/acre (OC) 48 7
  RANGE OF ACTIVITY: Pests: broad (many insects); Natural enemies: most
  PERSISTENCE: Pests: short; Natural enemies: intermediate
  MODE OF ACTION GROUP NUMBER1: 1B
  COMMENTS: For use on oranges, grapefruit, lemons, and tangerines. Apply at petal fall.
 
D. CHLORPYRIFOS*
  (Lorsban Advanced) 2–7 pt/acre (A) 5 days See comments
    . . . or . . .    
    2–7 pt/acre (OC) 5 days See comments
  RANGE OF ACTIVITY: Pests: broad (many insects); Natural enemies: most
  PERSISTENCE: Pests: short (low rates), intermediate (high rates); Natural enemies: short (low rates), intermediate (high rates)
  MODE OF ACTION GROUP NUMBER1: 1B
  COMMENTS: For use on all varieties. Do not apply during daylight hours of bloom period. Preharvest interval is 21 days for up to 7 pt/acre and 35 days for over 7 pt/acre.
 
E. DIMETHOATE 4 0.5–2 pt/acre (OC) 14 days 15
  RANGE OF ACTIVITY: Pests: broad (many insects); Natural enemies: most
  PERSISTENCE: Pests: intermediate; Natural enemies: long
  MODE OF ACTION GROUP NUMBER1: 1B
  COMMENTS: For use on oranges, grapefruit, lemons, and tangerines.
 
F. BETA-CYFLUTHRIN*
  (Baythroid XL) 6.4 fl oz/acre (OC) 12 0
  RANGE OF ACTIVITY: Pests: broad (many insects); Natural enemies: most
  PERSISTENCE: Pests: intermediate; Natural enemies: intermediate (low rates), long (high rates)
  RESISTANCE: in some citrus thrips populations in the San Joaquin Valley
  MODE OF ACTION GROUP NUMBER1: 3A
  COMMENTS: Only a single application may be made per crop season. To reduce the potential for resistance, make a total of only one pyrethroid application (for all pest species) per year. Do not apply within 25 feet of lakes, reservoirs, rivers, permanent streams, marshes, or natural ponds, estuaries, and commercial fish farm ponds.
 
G. FENPROPATHRIN*
  (Danitol 2.4EC) 21.33 fl oz/acre (OC) 24 1
  RANGE OF ACTIVITY: Pests: broad (many insects and mites); Natural enemies: most
  PERSISTENCE: Pests: intermediate; Natural enemies: long
  MODE OF ACTION GROUP NUMBER1: 3A
  COMMENTS: Apply in 50–200 gal water/acre. Use only on citrus trees 3 years or older. To reduce the potential for resistance, make a total of only one pyrethroid application (for all pest species) per year. Do not apply in the vicinity of aquatic areas.
 
** A - Aircraft applications 5–20 gal water/acre.
  OC - Outside coverage uses 100–250 gal water/acre.
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 ("un"=unknown or uncertain mode of action) are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/.

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, Entomology, UC Riverside and Kearney Agricultural Center, Parlier
  • J. G. Morse, Entomology, UC Riverside
  • N. V. O'Connell, UC Cooperative Extension, Tulare County
  • P. A. Phillips (emeritus), UC IPM Program, UC Cooperative Extension, Ventura County
  • C. E. Kallsen, UC Cooperative Extension, Kern County
  • D. R. Haviland, UC Cooperative Extension, Kern County
Acknowledgments for contributions to Insect, Mites, and Snails:
  • J. Barcinas, E.S.I., Corona, CA
  • R. Dunn, Badger Farming Co., Exeter, CA
  • J. Gorden, Pest Management Associates, Exeter, CA
  • H. Griffiths, E.S.I., Corona, CA
  • D. Machlitt, Consulting Entomology Services, Moorpark, CA
  • C. Musgrove, retired entomologist, Riverside, CA
  • K. Olsen, S & J Ranch, Pinedale, CA
  • 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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