966 



FAMILY XXX. — HYDRO METRID>E. 



and New England west to Michigan, Illinois and Kansas, and 

 south and southwest to Florida, Louisiana and Texas. This 

 species is the //. I media of Say (I, 361) and most of the records 

 have been under his name, which was preoccupied. Martin 



(1900, 70) and Bueno 

 ( 1905, 12) have given ex- 

 cellent accounts of the 

 habits and life history of 

 this species. From the 

 former I quote as fol- 

 lows: 



"The appearance of this 

 insect is unique and exceed- 

 ingly grotesque for the body 

 is so elongate and the legs so 

 thin that it appears like a 

 minute Indian club stalking 

 about on the water. The 

 economy of this elongate form 

 becomes at once apparent on 

 studying the habits of Hydro- 

 metra. In the first place it 

 reduces the insect's weight''" 

 to the minimum and so les- 

 sens the liability of breaking 

 through the treacherous sur- 

 face film upon which the life 

 of this aquatic pedestrian is 

 passed. In the second place 

 the long cylindrical body is 

 so like a bit of twig in ap- 

 pearance that Hydrometra is 

 protected from its enemies 

 and concealed from its prey 

 which do not in the least sus- 

 pect in this apparent straw the presence of a deadly foe. 



"The peculiar habitat and elongate form have given rise in the male 

 to a secondary sexual character which consists of two notched projec- 

 tions on the under side of the sixth abdominal segment. The object of 

 these is to fit over the lateral keels of the female abdomen, thus steady- 

 ing the abdomen of the male during copulation. This is rendered neces- 

 sary not only by the elongate abdomen, but also because it is necessary 

 for the insects to maintain their balance upon the water or run the risk 

 of breaking through the surface film, an accident very likely to cause 

 death by drowning. Hydrometra is a carnivorous insect, its food con- 



Fjk. 192. a, Male genitalia ; h, dorsal view of 

 insect X 10 ; c, side view of head. 



(After Garman, Hemiptera of Connecticut ) . 



"The weight is not reduced, but is distributed over a wider area of the surface 

 film. (W. 8. B.). 



