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, Trigono- 

 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, Melanoplus, 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 

 are, however, to be classed among the 

 beneficial insects, for they undoubtedly 

 destroy great numbers of the pestiferous gnats, mosquitoes, and 

 flies. 



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 

 JEshna constricta (PI., Fig. 15), M. crenata, M. septentrionalis, the 

 type of which was from Labrador, four species of the genus Somato- 



FIG. 14. 

 Nymph of the Dragon-fly. 



