How to Manage Pests

UC Pest Management Guidelines

Alfalfa

Biological Control

(Reviewed 1/17, updated 1/17)

In this Guideline:


Alfalfa is an important reservoir for natural enemies of insect pests. These natural enemy populations often develop in alfalfa fields and expand into other plantings such as cotton, melons, and beans.

Parasitic Wasps

Several species of parasitoid (parasite) wasps are found in alfalfa

Predators

Several species of predaceous bugs are found in alfalfa. These predators feed on a variety of pests such as alfalfa weevil larvae, aphids, alfalfa caterpillars, beet armyworm, western yellowstriped armyworm, webworms, leafhoppers, and three-cornered alfalfa hopper.

Birds are important predators of insect and rodent pests in alfalfa. Egrets, ibis, and gulls feed on crickets, cutworms, and other insects that are forced to move at the leading edge of flood irrigation water. Blackbirds eat alfalfa weevil larvae, aphids, cutworms, and other insect pests.

Treatment Considerations

Do not apply pesticides to alfalfa until the economic treatment level for a specific pest is reached and the predators and parasites have been assessed for their potential role in controlling the pest. Pesticides often harm natural enemies, leading to severe secondary pest outbreaks. See RELATIVE TOXICITIES OF INSECTICIDES AND MITICIDES to find out which pesticides are most compatible with natural enemies.

NATURAL ENEMIES AND THEIR COMMON PREY IN ALFALFA

Scientific Name Common Name Prey
PARASITOID (PARASITE) WASPS
Anaphes sp. Lygus bug eggs
Aphidius spp. Aphids
Bathyplectes curculionis, B. anurus Alfalfa weevil and Egyptian alfalfa weevil larvae
Cotesia (=Apanteles) medicaginis Alfalfa caterpillar
Hyposoter exiguae Beet armyworm and western yellowstriped armyworm
Trichogramma spp. Caterpillar eggs
PREDATORS
Chrysoperla sp., Chrysopa sp. and others Lacewings Aphids and small caterpillars
Coccinella septempunctata, Coccinella spp. Sevenspotted lady beetle Aphids and whitefly
Collops spp. Collops beetles Various small insects
Geocoris spp. Bigeyed bugs Aphids and small caterpillars
Hippodamia convergens Convergent lady beetle Aphids and whitefly
Nabis spp. Damsel bugs Caterpillars and other insects
Orius spp. Minute pirate bugs Aphids and small caterpillars
Scolothrips sexmaculatus Sixspotted thrips Various small insects, eggs, and mites
Various species Spiders Caterpillars and other insects
Zelus spp., Sinea spp. Assassin bugs Caterpillars and other insects

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Alfalfa
UC ANR Publication 3430

Insects and Mites

L. D. Godfrey, Entomology, UC Davis
E. T. Natwick, UC Cooperative Extension, Imperial County
P. B. Goodell, UC IPM Program and Kearney Agricultural Research and Extension Center
R. F. Long, UC Cooperative Extension, Yolo County
V. M. Barlow, UC Cooperative Extension, Riverside County and UC IPM Program

Acknowledgment for contributions to Insects and Mites:
D. R. Haviland, UC Cooperative Extension, Kern County
M. Rethwisch, UC Cooperative Extension, Riverside County (Blythe)
C. G. Summers, Entomology, Kearney Agricultural Research and Extension Center

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