HYDOMETIUDiE. 
695 
Fig. 462— Mesovelia mulsanti. 
record, being known previously from Ceylon and from the Nearctic 
and Neotropical region. 
Hydrometrince—Hydrometra vittata , 
Stab, is the sole species of this sub-family 
found in India. The extremely linear 
form, the very elongate head with the 
eyes set in the middle and the antennse 
at the apex make this a very striking in¬ 
sect. It is found on still water or on 
the mud at the sides of tanks and is a 
sluggish inactive insect, possibly pre¬ 
daceous. 
Veliince .—Though the Palearctic Velia 
currens, Fabr., has been found in the 
extreme North of India, few other species 
appear to occur and few are likely to 
be found in the plains. Microvelia singalensis, Kby., has been found 
to feed on larvae of Culex fatigans in India (F. M. H.). 
Gerrince .—At least five species of Gerris are known to occur in the 
plains of India, one or more of which are likely to be found in any slow 
moving or still fresh-water. These are elongate dark coloured insects 
with long posterior legs, the forelegs and antennae of moderate length, 
the beak short, curved and formed as in the Reduviidce. These insects 
move actively on the surface of water and are predaceous upon insects 
sucking out the juice of any which fall into the water or alight there. 
They are to some extent gregarious and in large tanks or lakes become 
very abundant. G. fluviorum, F G. fossarum, F., and G. spinolce, Leth. 
et Sevn., are common large forms; G. nitida, Mayr., and G. tristan, 
Kirk., represent the smaller forms. 
Halobates are marine insects and while three are reported from the 
Indian Ocean, a fourth is found abundantly on the West Coast during 
May, when strong winds blow in from the sea and apparently bring in 
abundance of these insects, which are helpless on the sand. This is 
Halobates germanus, Buch., a pretty little grey insect, not hitherto 
recorded from this country. J. J. Walker has noted the occurrence of 
Halobates on the surface of the Indian Ocean at a distance of 500 miles 
from the nearest land (Ent. Mo. Mag., 1900, p. 115). 
