Hale — Aquatic Hemiptera " 311 



seems certain, a(|uati(' Inigs feed upon these larvae in their native ponds, there is 

 every reason to snppose that tliey, initij^ate the inosq\iito nnisanee, and arc 

 thus of considerahle economic importance. The malaria-carrying' mos([nit()es 

 particularly, breed in isolated pools and temporarily inundated "'rass-grown 

 hollows, localities in which fishes do not usually occur, but to which aquatic l)ugs, 

 possessing: the power of flight, have easy access. 



Reproduction. Excepting in Biaprepocoris, the sexes are easily distin- 

 guished, the structure of the pala alone being sufficient indication. The abdonuMi 

 of the female is symmetrical, while in that of the male the segments are irregular 

 and distorted (fig. ;-i39A). The male is often also provided with a curious oi-gan, 

 situated on the sixth segment of the uppei- side of the abdomen. This was dis- 

 covered by F. B. White ("') and designated the strigil or strigiliform process. Ft 

 consists of a somewhat convex disc mouuted on a pedicel, and composed of over- 

 lapjiing, striated, chitinous plates, the striae l)eing directed inwards (fig. 34r)s) : 



;•/ -Striifil. 



Fig. 339. Porocorixa eitrynonie . A, upper side of abdomen of male ; B, eggs and lar\a, probably 



of this species. 



the utility of this structure is not clear, but it has been suggested that it 

 constitutes portion of a secondary stridulatory apparatus, possibly used duiing 

 flight. In the hitherto unknown male of Dhiprfpocoris there it yet another foi-m 

 of abdominal apparatus, also apparently stridulatory (fig. ^HOs). 



Although a species may vary in size in ditferent localities, 1hc females ai-e, 

 as a rule, slightly larger than the males. 



Fig. 339b shows the eggs and newly-hatched larva of an Australian species, 

 probably Porocorixo eiirynome. In autumn (April) 1921, numbers of the ova 

 were deposited on the thicker stems of a water-plant {Potaniofjeton sp.) in the 

 Torreus River, Adelaide; the smooth stems of a grass overhanging the banks, and 

 in places submerged, were also utilized, but the ova were always attached to 



(5) White, Joe. cit., p. 60, 



