The species Crioceris asparagi is commonly known as the asparagus beetle and causes wide spread damage to the asparagus plant. The damage is inflicted through feeding by both the larvae and adult, which form on the spears, leaves and shoots resulting in an unmarketable product.
The adult asparagus beetle is smooth, shiny and slightly elongated. The wing covers of the beetle have 4 distinct yellow squared spots with a red outer margin. The thorax is red with two small blue spots. The eggs are elongate and dark brown in colour, making the eggs stand out in vegetation. The larvae of C. asparagi are humpbacked and very plump with many wrinkles. They are grey in colour with a distinct black head.
Optimal conditions for infestation
Immediately following the appearance of shoots, the asparagus plant is susceptible to C. asparagi damage, especially during a dry season or if dry and wet periods occur in an alternate manner.
Start scouting plants in early May or just following the emergence of the asparagus plants and continue checking throughout the remainder of the growing season. The optimal scouting time for asparagus beetles is in the afternoon when they are most active. An insecticide application should be programmed or performed when the damage to the crop leaves becomes apparent.