Asparagus beetles—Crioceris spp.
The asparagus beetle, Crioceris asparagi, and the spotted asparagus beetle, C. duodecimpunctata,
may both be found in gardens. In California C. asparagi is more likely to be found. Larvae are
dark green-gray grubs about 0.75 inch (9 mm) long when full grown. Asparagus beetle adults may be bluish
black beetles with a red prothorax and yellow spots and red borders on wings. Spotted asparagus beetles
are reddish orange beetles with black spots.
Adults of the asparagus beetle chew the growing tips of spears in spring leaving brown stains, scars,
or blemishes. Larvae may chew ferns, causing them to appear bleached. Spotted asparagus beetle larvae
feed primarily inside berries while adults do minor damage to ferns.
Remove spears promptly. Handpick beetles
or wash eggs, larvae, and adult beetles off with a strong
stream of water. Clean up debris and remove and destroy
ferns by proper pruning in
late fall to reduce overwintering sites for adults. Avoid
insecticides because of potential harm to parasites and predators,
and damage is not usually serious enough to warrant it.
Applications of a pyrethrin spray
may be effective against larvae when they are young.