If you grow asparagus, you probably have asparagus beetles.
There are two basic forms of asparagus beetle: Crioceris asparagi, and the spotted asparagus beetle, C. duodecimounctata. Asparagus beetles are not normally a problem in California, but it is a good idea to know what to look for in case populations become troublesome.
Asparagus beetle identification
Adult asparagus beetles are blueish-black with a red thorax. They are less than 1/2” in length and their wing covers (elytra) have red edges and yellow spots. Spotted asparagus beetles are orange with black spots. The larvae are dark grayish-green and 3/4 of an inch long.
Asparagus beetle damage
Asparagus beetles feed on the tips of delicious young shoots, leaving scars and blemishes. Later in the growing season, they will feed on stem surfaces and leaves. Larvae may feed on the ferns, leaving a bleached appearance. Asparagus beetles can kill a plant.
How to repel asparagus beetles
Remove damaged spears to prevent other infestations or infections. Remove beetles by handpicking and wash eggs and larvae from plants with a strong stream of water from a hose. Remove aboveground growth in late fall to eliminate overwintering sites.
Basil, parsley, tomato, and nasturtium has been shown to repel asparagus beetles, making them good companion plants for asparagus.
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