If you are growing asparagus, then it is that time of year to be aware of the only insect pest of asparagus; the common asparagus beetle. Adult beetles are only 1/4 inch long. Adults emerge from the soil in early spring and fly to new asparagus shoots where they mate and feed. Females lay up to 30 eggs on the end of spear tips as they emerge from the soil.
Common asparagus beetles overwinter underneath plant debris, loose bark, or hollow stems of old asparagus plants. The life cycle can be completed in eight-weeks. There are two generations in Kansas. The adults and larvae feed on asparagus spears and can defoliate ferns if populations are extensive. Larvae consume leaves and tender buds near the tips, which leaves scars that eventually turn brown. Damage caused by larvae interferes with the plant’s ability to photosynthesize (manufacture food); thus, depleting food reserves for next year’s crop.
To help protect your asparagus patch from beetles: applying insecticides; handpick eggs, adults, and larvae and place into a container with soapy water; and/or remove any plant debris after the growing season to eliminate overwintering sites for adults. Insecticides should be applied as soon as common asparagus beetles are present, and again in late summer through early fall to kill adults before they overwinter. Thorough coverage of all plant parts is important in suppressing populations.
By: Cassie Homan
