The biology of Cryptochaetum (Diptera) and Eupelmus (Hymenoptera) parasites of Aspidoproctus (Coccidae) in East Africa

Abstract

Tropical and certain parts of subtropical Africa constitute the home of the genus Aspidoproctus (Coccidae, Monophlebini). The genus is remarkable in several ways, but chiefly because of the very large size attained by some of the species. A. maximus and A. giganteus are almost certainly the largest scale insects in the world, the female being well over 1 in. long and as much as ¾ in. thick. Owing to the relatively degenerate structure of scale insects in general, and in particular because of the poor development of the circulatory and tracheal systems, the biology of scale-inhabiting parasites is always of interest. This is particularly the case in relation to problems of respiration, and many scale parasites are already known (Thorpe, 1931, 1934, 1936) which exhibit very striking respiratory adaptations. Previous to the present paper no parasites had been recorded from the genus Aspidoproctus, yet it appeared extremely improbable on general grounds that these insects were immune from the attacks of the usual dipterous and hymenopterous parasitoids. Accordingly, when opportunity came to visit East Africa, attention was directed particularly to this problem; for it was felt that with insects of such large size and having such a thick dorsal cuticle, the problems to be overcome by the internal parasite would be intensified tenfold, and that any species found would be likely to exhibit structural and physiological adaptations of unusual interest. That this is indeed the case the present paper will show.