590 THE STUDY OF INSECTS. 



of attack of these parasites is between two abdominal 

 segments of the host. The presence of one of these para- 

 sites is indicated by an irregularity in the outline of the 

 abdomen of the infested wasp or bee ; and, too, the heads 

 of the pupa cases of the parasites can be seen project- 

 ing from the suture. " The head of the pupa case of the 

 male is convex, that of the female is flat ; specimens con- 

 taining male pupae can be kept confined with proper 

 food until the parasite is hatched." (Le Conte and Horn.) 

 Two genera occur in this country, Stylops (Sty'lops), 

 which infests bees of the genus Andrena (An-dre'na), and 

 Xenos (Xe'nos), which infest wasps of the genus Polistes (Po- 

 lis'tes). Certain 'foreign genera infest ants, cockroaches, and 

 homopterous insects. 



Suborder RllYNCHOPHORA (Rhyn-choph'o-ra). 



The Snout-beetles. 



This suborder includes the insects commonly called 

 snout-beetles, of which ten families are represented in North 

 America. With these insects the head is more or less 

 prolonged into a beak, which is sometimes longer than the re- 

 mainder of the body. The most distinctive characteristics of 

 this suborder are the absence of the gula, there being only 

 a single gular suture (Fig. 720, -.$), and the fact that the 

 epimera of the prothorax meet on the middle 

 line behind the prosternum (Fig. 720). 



A monograph of the North American 

 species of this suborder by Le Conte and Horn 

 is published by the American Philosophical So- 

 ciety, Philadelphia. 



The family RHINOMACERID.E (Rhin-o-ma- 

 FIG. 720. cer'i-dae) includes a small number of Snout- 

 beetles in which the elytra have no fold on the lower sur- 

 face near the outer edge, but in which the labrum is distinct. 

 The head is prominent, not deflexed ; the snout is as long as 

 the prothorax, rather flat, narrowest about the middle, wider 



