Effects of Castration ni Insects 42^ 



their hosts. The results are an atrophy of the reproductive organs 

 (parasitic castration) and a weakening of the wmg-muscles, so 

 that the grasshoppers have a disinchnation to fly. For this latter 

 condition, which is described as a "kind of rhachitis, " Kiinckel 

 d'Herculais suggests the name "aptenia." Like the brachyptery 

 of the Lasius mermithogynes, it points to an intimate correlation 

 between the development of the reproductive organs and the 

 wings, a correlation which is also clearly demonstrated in most 

 insects b\' the coincident maturation of the former and full devel- 

 opment of the latter organs at the beginningof theimaginal instar. 

 The extensive literature on entoparasitic Diptera and Hymen- 

 optera, if carefully searched, would probably yield a number of 

 accounts of parasitic castration. Pantel ('09), in an important 

 paper, distinguishes both direct and indirect parasitic castration 

 as the result of the infestation of lepidopteran larvae with the 

 larvae of tachinid flies. In the former case the fly larvae live in 

 the testes of the lepidopteron and destroy the gonadic elements 

 directly. In the latter the gonads suffer atrophy through the 

 action of the parasites on the other viscera. The only cases I 

 have found in which the host shows a modification of its external 

 sexual characters astheresult ofsuch castration, are the homoptera 

 Typhlocyba hippocastani and douglasi, which are described by 

 Giard ('89/', '89^) as being infested with a dryinid hymenopteron, 

 Aphelopus melaleucus and a pipunculid dipteron, Chalarus 

 (Ateloneura)spuna. The females of both species of Typhlocyba, 

 whe:;castratedbyAphelopus,have theovipositormuch reduced; the 

 Chalarus alone seems to have less eflect on this organ. The penis 

 of the male T. douglasi islittle modified by either of the parasites, 

 but in T. hippocastani infested with Chalarus, this organ shows a 

 decided reduction in size and simplification of structure so that 

 the specific characters become profoundly modified. None of 

 these modifications, however, indicates any tendency to take on 

 the characters of the opposite sex. 



6. Social Parasitic Castration 



This category is not sharplv marked off from the preceding, 

 for if we define it as including those cases among social insects 



