APPENDIX I 439 
together the stones and sticks. In some species the entire case is 
made of silk. Some five or six species have been recorded from 
Labrador. Limnophilus subpunctatus is a common species which 
is also found in Lapland. Desmataulius planifrons is recorded by 
Professor Packard from Okkak. 
The Hemiptera, or true bugs, are poorly represented, — two 
leaf-hoppers, including Deltocephalus debilis ; a small bug, T'rigono- 
tylus ruficornis; and one of the ‘“water-boat-man,” Corisa, are 
all that have been discovered. Equally scarce are the Orthoptera, 
only one species of grasshopper, Welanoplus, having been recorded. 
The Odonata, or dragon-flies, are among the most active and 
swift-flying of insects, darting back and forth over the ponds and 
streams and turning suddenly as they seize 
any unfortunate midge that comes within 
their reach; or alighting on the tip of a 
dead stick or reed from which vantage- 
point they can swoop like hawks upon 
their prey. Thus they are in many sec- 
tions of the country known by the popular 
name of mosquito hawks. 
The dragon-fly lays her eggs in the 
water, where the young or nymphal stages 
are passed. The nymph (Fig. 14) is a 
clumsy, awkward creature, crawling over 
the mud and among decaying vegetation, 
where it will lie partly concealed until its 
unsuspecting victim comes within reach 
of its extensible lower lip, which is armed 
with a pair of jawlike hooks. They are 
voracious feeders and not at all particular, 
for young fish are frequent victims. They Fic. 14. 
are, however, to be classed among the 
beneficial insects, for they undoubtedly 
rey great numbers of the pestiferous gnats, mosquitoes, and 
ies. 
After moulting several times, the nymph, when it attains its 
full size, crawls out upon some stick or plant, the skin splits longi- 
tudinally along the back, and the adult dragon-fly emerges. The 
life of the adult is from twenty to forty days, depending on cli- 
matic conditions, the more northern latitudes being unfavourable. 
About three hundred species are known from the whole of North 
America, of which only eight have thus far been collected in Labra- 
dor, including such large and widely distributed species as 
Aishna constricta (Pl., Fig. 15), 4. crenata, 42. septentrionalis, the 
type of which was from Labrador, four species of the genus Somato- 
Nymph of the Dragon-fly. 
