Aprostocetus hagenowii is a black parasitoid of about 3 mm. The male is smaller than the female. The female lays her eggs in the egg parcels of cockroaches. After hatching the young parasitoid larvae start eating the young cockroach nymphs within the egg parcel. They kill the young cockroaches and when full grown they pupate and finally hatch as adults in the egg parcel. Immediately after hatching they gnaw a hole in the egg parcel. One after the other the new born adult parasitoids will move out of the egg parcel trough this same hole. It is not visible from the outside whether a cockroach egg parcel is parasitized or not.
Mode of Action:
Aprostocetus hagenowii (= Tetrastichus hagenowii = Tetrastichodes hagenowii) is only effective against species of cockroaches that produce egg parcels (eg Periplaneta australasiae and Periplaneta americana). A female lays all her eggs in only 1-2 cockroach parcels. From a cockroach egg parcel, 60-70 new parasotids may be born. When the parasitoids have come out of the egg parcel, they immediately start mating. An unfertilized egg of the parasitoid will result in a male whereas a fertilized egg will become a female. There are usually about 80% females. The effect of Aprostocetus only becomes noticeable in the longer term, after several months.
Aprostocetus can be used the whole year through. It prefers higher temperature as well as higher humidity conditions.
Effect of Aprostocetus
- first sign of activity visible when an egg parcel is found with a hole
- however this is hard to notice
- takes at least 2-3 months before you may find them
- in the long run population of cockroaches will go down
- cockroach population will never disappear completely