Asparagus Beetle

HOSTS

• Asparagus

OVERVIEW

The asparagus beetle, Crioceris asparagi, is a leaf beetle in the family Chrysomelidae. This beetle feeds exclusively on asparagus and is native to Europe. The asparagus beetle is more economically injurious than spotted asparagus beetle. Although the asparagus beetle dominates in other asparagus-growing regions such as California, both asparagus and spotted asparagus beetle are equally abundant in Utah.

DESCRIPTION

Asparagus beetle eggs are brown, oval, and are individually cemented on asparagus plants. Asparagus beetle eggs can be distinguished from spotted asparagus beetle eggs because they are cemented on their end rather than their side. Larvae are plump and brown with a dark head capsule and chewing mouthparts. Larvae have three pair of legs on the thorax and fleshy prolegs near their hind end for grasping plants while feeding. Pupae resemble adults except for the poorly developed wings and yellow color. Adults are brightly colored leaf beetles, with the head, antennae, and legs bluish black in color. The forewings can be variable in color, but in general, each wing is bluish black with three white spots and orange wing margins. Adults are reluctant to fly away when disturbed, but will drop from plants and "play dead" to avoid predation.

BIOLOGY

There are 2-3 generations of asparagus beetle per year in Utah, but the third generation may be small in colder parts of the state. Asparagus beetles overwinter as adults in hollow asparagus stems, under weeds or other plant debris, or under loose tree bark. Temperatures determine beetle emergence every year; adults begin feeding on spears as soon as they break through the soil surface in early spring.

SYMPTOMS

• Adults can consume leaves, and scar spears and stems.
• The most serious damage is caused during the spring when adults are feeding on new spears.
• Occasional damage can occur during summer, but rarely stunting growth or reducing yield.
• Larvae feed on berries, but this is usually not economically important unless growing asparagus for seed.
• Females cement eggs onto spears or ferns causing aesthetic damage (eggs are not easily washed away or easily removed).

GENERAL MANAGEMENT

Predatory beetles and parasitoid wasps will help keep populations to tolerable levels in most situations. Removing volunteer asparagus will prevent population spread over time. Minimizing weeds or other debris near asparagus will make sheltered areas less favorable for overwintering adults. 

INSECTICIDES

For asparagus with persistent beetle damage, insecticides can be used to control adults and larvae. Consider reduced risk insecticides first because they have a short residual and are not broad spectrum.

• Residential: neem oil, kaolin clay (Surround), diatomacious earth, pyrethrins, spinosad
• Commercial: pyrethrins (Azera), spinosad (Entrust, Success), carbaryl (Sevin), permethrin (Ambush)