Asparagus beetle [ Crioceris asparagi ] is a harmful pest of Asparagus plants and can significantly reduced the yield to harvest. The adults overwinter in leaf litter and vegetation. The adults can fly to infect plants and then move onto infect other plants. There are normally 2-3 generations a year from May-September. The adult beetles become active in May and the females can lay 80-90 eggs each, once the temperatures are over 14.c, these eggs take about 3-10 days to hatch into larvae, which are grey to white colour. These larvae are active for 10-15 days depending on temperatures before they fall off the Asparagus plant to pupate in the soil before emerging as new adults.
Damage and Symptoms
Both the adults and the larvae feed on the Asparagus stems and foliage. Often the foliage will dry up and go brown, in severe cases the plants are defoliated. The larvae and adults can also excrete a black fluid onto the Asparagus spears, which contaminates them. Asparagus beetle attack can also lead to a very poor harvest the following season.
How to prevent and control Asparagus beetle
Once beetles and larvae are observed , hand pick them off the plants if possible. Remove vegetation in the winter that the adults can overwinter in. To control the pest, apply Asparagus Beetle Killer nematodes, these nematodes are applied directly onto the Asparagus beetle larvae, which they kill. The nematodes are applied when the larvae are present on the plants.
See Asparagus Beetle Killer for more details