Sept.,i903.] BuENO : Life-History of Pelocoris Femorata. 167 



film. 'I'his is done, as is usual with the atjuatic Heniijjtera, for the pur- 

 pose of renewing the air coating the abdomen and stored under the 

 hemelytra. In renewing its supply of air, Pe/oc-or/s sometimes appears 

 to protrude the terminal abdominal segments to break through the sur- 

 face. It also separates the tip of the abdomen and the hemelytra in 

 such a manner that a comparatively large aperture is formed at the sur- 

 face. While under water the insect may be seen to pass its swimming 

 legs through the abdominal air-coating a few times every now and then, 

 somewhat as does Corixa and possibly for the same purpose of renew- 

 ing the oxygen. Some of the individuals from which I have made these 

 notes, when taken, had a fungoid growth on the hemelytra and thorax. 

 This, however, does not seem to be in any way injurious. I have one 

 individual in this condition in my aciuarium, where it has been for the 

 last four months. When in captivity, I have fed them on flies, one 

 apiece every day, which appears to have been enough. Sometimes 

 three or four will fasten on one insect, feeding together very amicably. 

 Pelocoris is fiercely predaceous, and its salivary secretion must be 

 highly toxic. In a thoughtless moment, I put a Bclostoma {ZaitJia) 

 nymph in the a([uarium with these insects. It was no sooner in the 

 water than it was .seized, and although I forcibly rescued it immedi- 

 ately, it died in about a minute. 



According to De Geer, the lOuropean Ilyocoris (^Nai/coris) cimicoi- 

 des Linne, flies by night, and it may safely be assumed that our Pelo- 

 coris does the same, although I have never seen it. At any rate, its 

 wings are well developed and apparently powerful. 



In common with EelostomidK, Nepidi^i and Corixidae, Pelocoris is 

 at times found with water mites fastened to it, especially under the 

 hemelytra, or at the suture dividing the thorax and i)rothorax. * 



Pelocoris foiiorata overwinters in the adult form, and survives till 

 the following autumn. Oviposition begins in the spring, just how 

 early I am unable to say, and continues at least till the middle of 

 summer, when the insect begins to come to maturity. I have taken 



* I have very rarely found this to be the case with Notonecta, although I have 

 taken Notonecta irrorata Uhl. with mites under the wings. In general, the water- 

 bugs are attacked in about this order : Nepida; , Belostomidje, Corixida-, Naucoridce 

 and NotonectidcT?, the last named being the least susceptible. Yrom the facts that 

 this is ^Iso the order of their activity ; that Ranatra, a most sluggish insect, is the 

 most heavily parasitized ; and that A^otonecta, which is constantly on the move, the 

 least, it seems fair to infer that the water mite selects for its attacks those msects that 

 disturb it least. 



