Oystershell scale parasitoid - Aphytis mytilaspidis

This female was has been attracted to a sex pheromone trap of San Jose scale and caught on its sticky base.

Aphytis mytilaspidis was introduced to New Zealand accidentally. It was first recorded in 1935. It is a solitary ectoparasite, feeding on and attached to the exterior of the soft body of the scale insect. Although mussel scale is considered a preferred host of this parasitoid, it has been reported as the most common parasitoid attacking oystershell scale populations in Otago and is considered an important parasitoid of oystershell scale overseas. It is also the dominant species caught in San Jose scale traps in Otago, where oystershell scale in the most common armoured scale host. There are no males. The female lays an egg under the scale cover on the exterior of the soft scale body. The wasp has three larval stages, a prepupa, and then pupates and emerges as an adult wasp. This leaves behind visible black particles or meconium excreted during the prepupal stage. There are several generations per year and it overwinters in the larval stage. Aphytis wasps generally lay 30-60 eggs in their lifetime. The adult wasps also feed on scale insects by piercing the scale with their ovipositor and eating the juices with a feeding tube. This activity can cause significant scale mortality.