It is widely known that the biological method for the control of insect pests is receiving considerable attention from Economic Entomologists at the present day. One of the insects against which this method is being tried is the common earwig (Forficula auricularia), which is a very serious pest of orchards, etc., in such countries as New Zealand where it it has been accidentally introduced from Europe.

Through co-operation between the Imperial Bureau of Entomology, Rothamsted Experimental Station, and the Cawthron Institute, Nelson, attempts have been made to control the earwig in New Zealand by the introduction of two Tachinid flies that are parasitic on it, Digonochaeta setipennis, Fln., and Rhacodineura antiqua, Meig. These flies are obligatory parasites, being entirely dependent on this particular host for the completion of their life-cycle, and they are lethal in effect. The larvae having emerged from their dead or moribund host, soon pupate, and it is in the pupal stadium that these insects can most conveniently be transmitted in cold storage. Mr. A. M. Altson, of the Imperial Bureau of Entomology, was in charge of this work in England in 1924 and 1925, but, unfortunately, owing to ill-health he was obliged to give it up. In the autumn of 1926, at the request of Dr. Tillyard, it was decided to forward a further batch of parasitic puparia to New Zealand. For this purpose large quantities of earwigs had to be captured in the field, and transferred to cages in the laboratory, in order that the parasites which emerged from the earwigs could be collected.