How to Manage Pests

UC Pest Management Guidelines

Pistachio

Darkling Beetles

Scientific names: Blapstinus spp., Coelus spp., and others

(Reviewed 10/14, updated 10/14, corrected 8/16)

In this Guideline:


DESCRIPTION OF THE PESTS

Darkling beetle adults range from 1/8 to 1/2 inches (3 to 6 mm) long and vary from black or bluish black to rusty brown. Darkling beetles may be hidden by dust or a thin layer of soil. Cylindrical, wirewormlike, soil-inhabiting larvae are light yellow to dark brown and range from 1/33 to 1/3 inch (0.8–8 mm) in length. They are often referred to as false wireworms.

Do not confuse darkling beetles (Tenebrionidae) with predatory ground beetles (Carabidae), which prey on various soil dwelling pests. Darkling beetles generally have clubbed antennae whereas predatory ground beetles do not.

DAMAGE

Adult darkling beetles can become a pest on young pistachio trees when they climb up the rootstock and eat the Kerman bud three to four weeks after budding. They can also damage emerging Kerman shoots during the spring following their first dormancy.

MANAGEMENT

Avoid discing weeds within the orchard or adjacent fields at the time of budding. Discing in crops like alfalfa has been known to promote migrations of darkling beetles. Monitor for darkling beetles during the first month after budding. If an unacceptable number of buds are being consumed, consider treating the orchard with a carbamate-based bait. It may also be possible to avoid damage by wrapping the trunk with double-sided sticky tape to prevent beetles from crawling up the rootstock.

Common name Amount per acre** R.E.I.‡ P.H.I.‡
(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. CARBARYL
  (Sevin 5 Bait) 40 lb 12 365
  MODE-OF-ACTION GROUP NUMBER1: 1A
  COMMENTS: For nonbearing trees only.
 
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 R.E.I. exceeds the P.H.I.. 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). For additional information, see their Web site at http://www.irac-online.org/.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Pistachio
UC ANR Publication 3461

Insects and Mites

D. R. Haviland, UC Cooperative Extension, Kern County
W. J. Bentley, UC IPM Program, Kearney Agricultural Center, Parlier
R. H. Beede, UC Cooperative Extension, Kings County
K. M. Daane, Biological Control, UC Berkeley and Kearney Agricultural Center, Parlier
Acknowledgment for contributions to Insects and Mites:
R. E. Rice, Kearney Agricultural Center, Parlier

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