The Larval and Pupal Anatomy of Stenomalus micans Ol. (Pteromalidae), a Chalcid Endoparasite of the Gout-fly of Barley (Chlorops taeniopus Meig.), with some Details of the Life History of the Summer Generation

Abstract

1. Two species of endoparasites, a Chalcid Stenomalus micans and a Braconid Coelineus niger, were found in every sample of “gouted” barley examined from a number of counties in southern England.2. Chlorops infestations were severe in 1928 in many districts, and the majority of the “gouted” shoots were of winter-type damage, of which 68 percent. were parasitised, two-thirds by S. micans.3. The larval anatomy of S. micans is described:(a) There are five larval instars, each of which is described.(b) The first larval instar appears to be partly predaceous.(c) The larvae can be kept alive for 5 days on the surface of normal physiological saline solution and moulting occurs, which enables the instar to be determined with certainty.(d) The tracheal system is devoid of spiracles until the fourth larval instar; spiracles then develop and are connected to the former rudimentary stigmatic trunks prior to the death of the host.(e) The fourth instar larva develops a cephalic boring armature which is used for breaking up the internal organs of the host and also to bore an exit hole through the latter's body wall.4. The pupa of S. micans is described and sex differences are indicated.