hungerford: aquatic hemiptera. 145 



it is laid, swells considerably as the embryo develops within. In fact 

 Bueno has noted that it gains one-half of its first length. 



Hatching. The hatching process is an interesting one, and easily 

 observed. A figure on Plate XVII shows the process at its beginning. A 

 rent, transverse to the long axis of the Qg^, takes place near the 

 micropylar end of the shell. The cap thus formed is gradually pushed off 

 and the bug by successive heaves comes forth. When part way out, the 

 fore limbs can be seen bound and outstretched upon the venter. When 

 the bug is nearly out of the shell it gives a backward heave. The mem- 

 brane breaks, and as it gradually slips back, the fore limbs are freed and 

 snap into normal position (femora outspread and tibiae appressed). 

 Shortly the whole animal is free and rights itself in the water, soon 

 swimming out to some support. The whole process may be completed in 

 four minutes. 



Behavior of Netvly Hatched. The little nymphs have a tendency to 

 cluster together — clump themselves together at the surface. They are 

 ready to strike for food as soon as their exoskeletons harden. The hatch- 

 ing of a given batch of eggs may last for a day or two before the male 

 frees himself from the Qgg mass. In this case the older, darker nymphs 

 feed upon the more feeble freshly hatched. 



Number of Instars. There are five nymphal instars. The total period 

 required for development from deposition of egg to adult was recorded 

 by Bueno for 3 individuals which took 43, 53 and 54 days respectively. 

 The various stages take about a week each, with a longer time for the 

 5th instar as a rule. One brood, hatched May 21, went into 2nd instar 

 May 26, into 3rd instar May 31, into 4th instar June 6, into 5th instar 

 June. 15, and adult June 25, making 5 days for the first, and 10 days 

 for the last nymphal instar, making with the six-day egg stage, a total 

 of 40 days. 



Fecundity. Egg-laden males may be taken throughout the warmer 

 part of the year. Bueno has found them in New York from middle of 

 May to the end of August. Here in Kansas they have been taken both 

 earlier and later. The female doubtless lays several batches in the course 

 of the season, each batch, as indicated by the counts on the males, rang- 

 ing from 65 to 159 eggs. Miss Slater said she found from 75 to 85, but 

 in Kansas specimens it was not uncommon to find as many as 150 eggs 

 on the back of the male. 



Longevity. These insects are long lived, living for more than a full 

 year at least. 



Food Habits. The nymphs have been fed in the laboratory upon 

 mosquito wrigglers, Corixids and like forms. The literature contains 

 a long list of the food organisms from fish to snails. Professor Todd, 

 in 1883, published a note in America^i Naturalist about a Belostoma 

 %-inch long that vanquished a fish three or four times its own length, 

 which was like a dace in form. 



Behavior. We are indebted to Severin & Severin for notes on the be- 

 havior of these bugs. They found them positively thigmotactic. As to 



10 — Sci. BuT. — 1669 



