Arrenoclavus koehleri (Blanch.) is a polyembryonic parasite of South,.American origin, of economic importance for the control of its known host, the potato tuber moth, Gnorimoscheriw operculella (Zell.), The parasite oviposits in the host's egg, and a polyembryonic group starts to develop inside the host larva. An average of 31,7 parasite larvae crowds the body of the host larva, under artificial laboratory conditions. The adult is small and black, having an average size bf 1,3 to 1,8 mm., the male being larger than the female. At 18°- 20° C., and 65% humidity, the parasite egg takes 22 days to hatch, the larva eight days to become full grown, and eight days from the time the pupa is formed until the adult emerges from the dried host skin. Sex ratio is one male to 3,43 females. The number of generations each year is determined by the availability of eggs of the host.
Under natural conditions in Quillota and Limache, the parasite becomes established in about 20% of the host population. Mass production is thoroughly described, and is an easy and economical process. So far, no other insect host of A. koehleri has been reported.

1 Resumen de la tesis presentada a la Facultad de Agronomía (U. de Chile) como requisito parcial para obtener el titulo de Ingeniero Agronómo.