SARRACMIA VaRIOLARIS. 



197 



while the leaves are young and vigorous, and it is while 

 this is abundant that so many insects are caught. Yet 

 even after I cannot detect the secretion, either in feel- 



FIG. 23. HAIRS ON THE WING AND OUTER SURFACE OF TUBE. 



ing or taste, the flies still find enough to attract them, 

 but it is in such small quantity that they sometimes fly 

 away after feeding a while, which they never do when 

 they get a good dose. I have taken flies that were stu- 

 pidly intoxicated, and placed them under a glass where 

 I could observe them, and I find they have a tendency 

 to stand on their heads until they die. The first flies 

 that are caught in a tube usually remain quiet, from the 

 fact that they are wedged down so tight that they can- 

 not move. This tendency to stand on their heads puts 

 them in such a position that it is impossible to extricate 

 themselves ; but as the tube extends upward it becomes 

 broader, and now the remaining flies that are caught 



