390 MR. J. B. GATENBY ON THE BIONOMICS, EMBRYOLOGY, 



that of Apanteles glomeraius, parasite o£ Pierines, is a beautiful yellow 

 coloui'. 



When the parasites have spun their cocoons, if winter is near they 

 hibernate generally as larvse inside their silken cells. If groups of cocoons 

 taken after the time of emergence of the adult parasites be examined 

 carefully, it will be noticed in the case of some cocoons that the parasitic fly 

 has emerged from I he cocoon by means of a beautifully even lid, which adheres 

 on one side to the body of the cocoon to form a hinge (PI. 24. fig. 1, at X). 

 This is the manner in which the Microgaster individuals emerge ; in the case 

 of other cocoons no such hinged lid is to be found ; instead there is found 

 an ugly uneven hole at one side of the end of the cocoon (PI. 25. fig. 9, X) : 

 this is the manner in which hyperparasites and hyper-hyperparasites emerge 

 from the Microgaster cocoons. 



It should at once be pointed out that not only Microgaster, but hyper- 

 parasites on Microgaster are attacked by other Hymenoptera, Ichneumonidse, 

 and Chalcididse. The naked, unprotected mass of cocoons, as in PI. 24. 

 fio-. 5, forms an attractive prey to other parasites who only need to bore 

 through the silken wall to deposit an egg near the body of the Microgaster 

 larva or pupa, or if the Microgaster has already been hyperparasitized, near 

 tiie body of the hyperparasitic larva or pupa. 



Having regard to the recent review (11) on the parasitic polyembryonic 

 Hymenoptera, which also mainly pay their attentions to moth larvae, it 

 mioht be thought that the Microgasteridse are polyembryonic. This opinion 

 would certainly be strengthened when it is remembered that parasitized 

 caterpillars of Pliilampelus produce as many as four hundred Microgaster 

 individuals (2). Nevertheless it seems a fact that these Braconids are not 

 polyembryonic ; several observers agree that Apanteles and Microgaster do 

 not lay their eggs singly (or a few) inside the egg of their host, as do the 

 polyembryonic forms. 



From the description of the Italian entomologist Martelli (3), I give the 

 following account of the manner in which Apanteles glomeratus parasitizes 

 the larv£e of Pieris hrassicce. The caterpillars are about three millimetres in 

 length when they are attacked by the Apanteles (Seurat (12)). The 

 Apanteles is an active, rather shy insect, about the same size as Microgaster 

 connexus (5 mm.) ; it beats among the leaves of the cabbage till it finds a 

 group of larvse about the right size. Martelli picturesquely describes the 

 agitation of the Apayiteles as it sights its prey. It now stealthily marches 

 forward little by little, rapidly vibrating its antennae. The latter movement 

 is very common among Hymenopterous insects (others as well). In many 

 other parasitic forms the sight of the prey causes an excited vibratory move- 

 ment of the antennae — the senses become tense, and the little insect stiffens 

 itself up for the not undangerous and extremely delicate task before it. The 

 task of the Apanteles is as follows ; — it has got to lay from sixteen to thirty 



