41 



B. dimorpha infection. The signs of infection in sexual 

 pupae have not been described. The development and histo- 

 pathological basis of the unique manifestations of this 

 disease are described here. 



Materials and Methods 



The progressive development of pathognomonic signs 

 was recorded by periodically photographing healthy and dis- 

 eased pupae. Diseased pupae exhibiting the minimal degree 

 of eye development necessary for diagnosis and healthy pupae 

 of corresponding age and size were paired and held in minia- 

 ture nest cells. The specimens were positioned on a plate 

 of nonglare glass above a black parabolic background, illum- 

 inated by an annular fiber optic illuminator, and photographed 

 through a stereomicroscope fitted with a polarizing filter. 

 Photographs were made ca every 48 hours until the healthy 

 specimen had eclosed and the diseased specimens had reached 

 maximum expression of pathognomonic signs. 



Specimens for both light and transmission electron 

 microscopy were fixed and embedded in epoxy resin. Tissue 

 specimens (heads, gasters, whole larvae, etc.) were prefixed 

 in buffered IZ osmium tetroxide (0.1 M sodium cacodylate 

 buffer, pH 7.5) for 30-60 minutes at room temperature, rinsed 

 in the same buffer, and partially hardened in buffered 2.5% 

 gluteraldehyde-1% acrolein (same buffer). Specimens were 

 washed in buffer and usually stored in Histocon (polyvinyl- 

 pyrrolidone, Tris-HCl, 11 chlorhexidine, distilled water; 



