138 THE UNIVERSITY SCIENCE BULLETIN. 



Mating. As in M. americana, described by Bueno. 



Oviposition. The writer finds the eggs placed much as in M. ameri- 

 ca7m, in a mass of jelly-like material just above the surface of the water 

 and attached to pebbles, stones, etc. Bueno noted them "on the under 

 side of duck weed. The head end pointed to the edge of the leaf." Each 

 egg is upon a stained pad of gelatinous matter as if it had used too 

 much adhesive. When first laid the egg is very white. 



Incubation. Bueno gives from 7 to 23 days. The writer has kept 

 many batches under observation in July, and finds the time to be around 

 six days. One lot contained 145 eggs. The darker color and the red 

 eye spots mark the older eggs. Thirty-two eggs laid July 25 showed 

 on the 27th faint yellowish circular spots, which later are the red eye 

 spots. On the 29th they hatched. 



Hatching. Bueno says the eggs split longitudinally for tr of their 

 length, and through this the nymph escapes. He looked for, but failed 

 to find, the "amnion or molt." The writer finds that the postnatal 

 molt does occur and that it bears an "egg burster" like the Gerris. 

 One was observed under the binocular to be just coming out. Swathed 

 in the thin membrane it struggles out. The black, shiny knife between 

 the eyes is attached to, and shed with the postnatal molt. Before this 

 membrane breaks, the legs are seen to curl around the tip of the abdo- 

 men. The antennae, beak and legs are outstretched upon the ventrum. 

 See plate XII for figure of the nymph within the egg. 



Fecundity. Bueno says a female holds two eggs at a time. The 

 writer noted 6 females that laid 145 eggs in five days. This means 

 nearly 5 eggs per female per day. It takes from 10 to 20 days to reach 

 the adult stage. 



Molting. In molting from one instar to the next the process is about 

 as follows: The old integument becomes quite rigid and sets upon the 

 water in a substantial manner. It splits longitudinally for some distance 

 down the dorsum, and the triangular piece between the eyes splits out 

 forward as in the large Gerrids. The antenna are directed laterally and 

 downward. The newly emerged nymph is white with red eyes. It rests 

 for a time perched upon the old nymphal skin. 



Feeding Habits. In the rearings these little bugs v/ere given plant 

 lice and house flies. In shallow petries they make out very well if only 

 there are Ostracods and Daphnians present in the water. The writer 

 has seen little first instar bugs eat Ostracods larger than themselves. It 

 is interesting to watch them maneuvering to pick out an Ostracod that is 

 floating with one surface at the film. The bugs feel around with their 

 little beaks, the terminal segment twisting here and there, playing over 

 the smooth impervious surface for a vulnerable point. If this is not 

 successful they will employ their fore legs in an attempt to roll over the 

 little Crustacean. The Ostracod that moves is the one that attracts their 

 attention and it is sought out and molested by these ever alert and 

 watchful pygmies of the surface. Here one succeeds in driving home 

 his barged stylets and with a backward jerk does an astonishing thing. 



