The Tachytes 



possesses its individual art, its own plan, 

 its one method. 



The nature of the food has no more effect 

 upon the larva's talents than the environ- 

 ment in which it lives or the materials em- 

 ployed. The proof of this is furnished by 

 Stiza ruficornis, another builder of cocoons 

 in grains of sand cemented with silk. 

 This sturdy Wasp digs her burrows in soft 

 sandstone. Like the Mantis-killing Tach- 

 ytes, she hunts the various Mantides of the 

 countryside, consisting mainly of the Praying 

 Mantis; only her large size requires them 

 to be more fully developed, without however 

 having attained the form and the dimensions 

 of the adult. She places three to five of 

 them in each cell. 



In solidity and volume her cocoon rivals 

 that of the largest Bembex; but it differs 

 from it, at first sight, by a singular feature 

 of which I know no other example. From 

 the side of the shell, which is uniformly 

 smoothed on every side, a rough knob pro- 

 trudes, a little clod of sand stuck on to the 

 rest. The work of Stizus ruficornis can at 

 once be recognized, among all the other co- 

 coons of a similar nature, by this protuber- 

 ance. 



163 



