420 William Morton Wheeler 



observer says: "It is, indeed, possible to predict from the length 

 of its forceps whether or not a male Forficula possesses gregarines 

 and whether these are present in greater or lesser numbers. Since 

 these parasites produce a diminution of a secondary sexual char- 

 acter, that is, the length of the forceps, without bringing about 

 absolute sterihty (complete castration being exceptional), it not 

 infrequently happens — and this is the case both on the beaches 

 of Wimereux and on the Fame Islands — that the individuals with 

 short forceps, namely, those containing parasites, are more nu- 

 merous than the individuals with long forceps." Giard is inclined 

 to believe that similar conditions may obtain in such beetles as 

 Xylotrypes gideon, Oryctes nasicornis and other Scarabaeidae 

 with high and low males. The low males of these beetles, however, 

 are not to be regarded as having acquired female characters, but 

 as having lost the male characters, so that, as Giard remarks, the 

 "infested individuals are generally paedomorphic as compared 

 with the normal form." 



In two of my former papers ('oi, '07) I described a pecuhar 

 case of parasitism in a Texan ant, Pheidole commutata. The 

 larvae of this insect are occasionally infected with nematodes of 

 the genus Mermis and develop into peculiar forms, which I have 

 called mermithergates (Figs. 6B and 6C). These are much larger 

 than the normal workers (Fig. 6y/), which they nevertheless resem- 

 ble in the structure and small size ofthe head, although they possess 

 small ocelli and in this respect resemble the queens. In thoracic 

 structure they approach the soldier form while the gaster is enor- 

 mously distended with Mermis and retains scarcely any vestiges 

 of the fat-body, reproductive organs and other viscera. The 

 behavior of these parasitized individuals is also peculiar, since 

 they never excavate the soil, nor care for the brood Hke the nor- 

 mal workers, but run about in a state of chronic hunger, begging 

 food from their uninfested nest-mates. Emery ('90, '04) has re- 

 corded the occurrence of mermithergates in quite a series of neo- 

 tropical ants, including Pheidole absurda and several Ponerinae 

 of the genera Odontomachus, Neoponera, Ecfatomma, Pachy- 

 condyla and Paraponera. 



In the cases described by Emery and myself only the worker 



