34 



Following infection with spores of B. dimorpha from 

 S. geminata , signs typical of infection in S^. geminata 

 develop in pupae of S^. invicta and S^. richteri . However, 

 pupae that are infected subsequently in these colonies (by 

 spores produced in siblings) develop atypical signs. The 

 blister-like clearings in the head and gaster are not apparent, 

 although faint clearing in the petiole may occur. Abnormal 

 eye development typical of the disease was noted, however 

 (Fig 5). Jouvenaz and Hazard were premature in their state- 

 ment that the course of the disease is identical in all 

 four species; they had examined only pupae infected with 

 spores produced in S_. geminata . 



The reason(s) for the failure of B. dimorpha to cycle 

 indefinitely in S^. invicta and S. richteri is unknown. Ob- 

 viously, they are "not well adapted" to these species, but 

 this merely restates our observations. Perhaps the cuticle 

 is less likely to rupture and cannibalization is less likely 

 in these species due to dehydration or putrif ication in 

 the intact state. The cadavers may then simply be discarded. 



