HUNGERFORD: AQUATIC HEMIPTERA. 93 



algae and slime floating on the surface, the color of which it matches 

 in the young stages." We have found it on the Sphagnum at the edge 

 of bog ponds in New York, and amidst the Typha, smartweed, spike- 

 rush, etc., growing in the shallow pools and ponds of Kansas, as well 

 as upon floating rafts of dead typha, or tangles of Spirogyra. It pre- 

 fers the footing such supports may offer to the open water. However, 

 it can walk upon the water when occasion demands. 



Hibernation. It winters as an adult in the trash about the pool, 

 coming out in early spring to resume activity. Wesenberg-Lund, 1913, 

 says that the species of Denmark winters in damp moss. 



Mating. There is some difference in the size of the sexes of this bug, 

 the male being smaller than the female. Martin says that the peculiar 

 habitat of this bug, combined with its elongate form, has given rise to a 

 secondary sexual character, which occurs in the H. stagnorum, as well 

 as in our own species. This consists of two notched projections on the 

 under side of sixth abdominal segment, close to the incisure between the 

 sixth and seventh segments. (See pi. XIII, figs. 8 and 9.) The first of 

 these notched elevations of the abdominal walls, he says, is to fit over the 

 lateral keels of the female abdomen, thus steadying the abdomen of the 

 male during copulation.* This is rendered necessary not only by the 

 elongate abdomen, but also by the fact that it is necessary for the insects 

 to maintain their balance upon the water or run the risk of breaking 

 through the treacherous surface film. 



Oviposition. Martin has given us a splendid account of the oviposition 

 of this bug. The writer has often seen the same process. The female 

 "exudes from the genital opening a drop of gummy gelatinous substance, 

 which she then presses against the object that has been closen to support 

 the egg. This sticky mass is the base of the egg stalk, and hardening very 

 soon, fastens the egg in place before it has left the body. The insect 

 now walks away from the stalk, thus freeing herself from the egg." 



The newly laid egg is creamy white, which after about half a minute 

 quite suddenly changes to a brown, the ends remaining lighter than the 

 body of the egg. The material with which the egg is attached appears 

 shiny and fluid for several minutes. 



The female places her eggs upon any support, a little above the surface 

 of the water as a rule. In the aquaria the eggs were placed upon the 

 vertical sides of the glass jars from the water level to two inches above 

 it. In nature the writer studied a colony of these insects that were living 

 on the shallow waters of a pool overgrown by cattail. It was early April. 

 The cattail seeds were sending out long sprouts, forming a green mat 

 upon the water. The marsh-treaders were laying their eggs upon these 

 sprouts. The browTi spindle-shaped eggs are much the color and shape 

 of the cattail seeds, which gives them a striking superficial resemblance, 

 which is showTi in the photograph on plate VI. 



Incubation. Martin gives 17 days for the duration of the egg stage. 

 Bueno says from 19 to 9 or 10 days. In Kansas, eggs laid the afternoon 

 of July 16, hatched July 20 in the afternoon, a period of four days! 



* Have observed mating often, but these processes -were not used. 



