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How to identify it
- Adults are small weevils about 0.2 inch long, gray to light brown with darker brown and gray markings down the back.[2][1]
- Larvae are legless and about 1/4 inch long when grown: pale green with a thin white stripe down the middle of the back and a dark brown to black head. Newly hatched larvae are tiny and yellowish green.[1][2]
- Feeding starts at the plant tips and works down, leaving skeletonized, bronzed leaves; adults leave thin linear scars on the stems.[1][2]
- Pupae form inside round, closely woven white cocoons spun on the ground.[1]
Look-alikes
| Look-alike | How to tell them apart |
|---|---|
| Alfalfa weevil | The two look identical and are told apart by biology and distribution. The alfalfa weevil overwinters in field trash and emerges in late winter or early spring, and in California it is the annual pest east of the Sierra Nevada and in the northernmost counties; the Egyptian alfalfa weevil moves into fields in late fall or early winter and may have displaced it in most other areas.[2] |
Where it lives
In California it may have displaced the alfalfa weevil everywhere except east of the Sierra Nevada and the northernmost counties, and it is a pest of desert-grown alfalfa in western Arizona.[2][1]
Biology and life cycle
Adults spend the summer resting (aestivating) in sheltered spots near alfalfa fields: weedy areas, under loose bark of trees such as eucalyptus, in rough-barked walnut trees and even under shake shingles on homes.[1][2]
In late fall or early winter they move into alfalfa fields. Females chew a hole in a stem and lay smooth, shiny yellow eggs inside living or dead stems a few inches above the soil, and the eggs hatch in 5 to 10 days.[2][1]
Larvae crawl up to the plant tips and feed for about three weeks, usually finishing around the first cutting; in western Arizona they can appear in January and peak from about late February to late March.[1][2]
New adults feed for 2 to 4 weeks before going into summer rest. There is usually one generation a year, though a smaller second generation has been documented in California's southern San Joaquin Valley.[1][2]
Natural enemies are not effective enough early in the season. Introduced Bathyplectes parasitic wasps attack the larvae, but the Egyptian strain often encapsulates and kills Bathyplectes curculionis.[2][1]
Damage and signs
- Young larvae feed on terminal buds and older ones on leaflets, skeletonizing and bronzing the leaves; heavy infestations can defoliate the crop, cutting yield and quality and damaging regrowth buds.[2][1]
- Damage is usually worst before the first cutting, and it can be severe under windrows left lying for days. This species is more likely than the alfalfa weevil to keep damaging the second and occasionally the third cutting.[2][1]
- Adult feeding generally does not cause significant damage.[2][1]
Health risk
It feeds only on plants; UC IPM and Arizona Extension mention no risk to people.[2][1]
Control
Prevention
Keep stands dense and vigorous; there are no resistant varieties, but well-adapted ones recover fast enough to tolerate some damage. Grazing sheep on the alfalfa in fall and winter can sometimes prevent serious damage.[1]
Sanitation
Control weeds in and next to alfalfa fields to reduce the adults that spend the summer there.[1]
Traps and physical control
Sweep for larvae: begin in early January in southern and central California, take five sweeps in each of four sections of the field, and check every 2 to 4 days once larvae appear. UC IPM's current threshold for treatment is an average of 20 or more larvae per sweep.[2][1]
Cutting the crop early, once most plants reach the bud stage, can sometimes prevent serious damage, and harvesting and curing kill most of the weevils. Survivors concentrate under the windrows, so watch the regrowth closely.[2][1]
Biological control
Early harvest instead of spraying protects the lady beetles, lacewings and parasitic wasps that attack weevil larvae and aphids.[1][2]
Pesticides
If counts reach the threshold, an insecticide may be needed; spinosad is acceptable for organic crops. Some weevil populations in California's Intermountain and Low Desert areas have developed cross-resistance to beta-cyfluthrin.[2]
Common questions
- Is the Egyptian alfalfa weevil a different insect from the alfalfa weevil?
- UC IPM treats them as two identical-looking weevils that differ in life cycle and distribution, and covers their management together.[2]
- Why are small gray weevils hiding under the shingles on my house in summer?
- They may be alfalfa or Egyptian alfalfa weevils. UC IPM says both spend the summer as adults in sheltered spots such as under loose tree bark or shake shingles on homes; Egyptian alfalfa weevils move back into alfalfa fields in late fall or early winter.[2][1]
- Should I spray or cut early?
- When the crop is near the bud stage, cutting early is often the better choice, and it spares beneficial insects; spray only when sweep counts reach the threshold.[1][2]
Sources
- University of Arizona Cooperative Extension, “Egyptian Alfalfa Weevil, AZ1046 (T. C. Knowles, August 1998).” extension.arizona.edu/sites/extension.arizona.edu/files/pubs/az1046.pdf (accessed 2026-11-08)
- University of California Statewide IPM Program, “Alfalfa Pest Management Guidelines: Weevils (Alfalfa and Egyptian Alfalfa).” ipm.ucanr.edu/agriculture/alfalfa/weevils-alfalfa-and-egyptian-alfalfa (accessed 2026-11-08)
- iNaturalist, “Hypera brunnipennis taxon page (order and family).” www.inaturalist.org/taxa/304794 (accessed 2026-11-08)