242 THE ENTOMOLOGIST. 



pierce the thorax (not the abdomen), to phice the wings horizontal, 

 inclining slightly forward, and to keep two pairs of legs behind 

 the wings. 



Diptera are very abundant on any warm day from earl}' spring 

 to late autumn. They may be taken in less numbers on cloudy, 

 and even cold, days. Through the winter there are species of 

 Nemocera to be found, so that the collector can occupy himself 

 from one year's end to another. 



A knowledge of the habitat of each family is essential to 

 systematic and successful collecting, and the sooner the entomo- 

 logist who embraces the study of Diptera learns these the better. 

 Again, man}' groups have a special manner of taking flight and of 

 behaving when on the wing, so that acquaintance with these various 

 peculiarities is necessary, as the chance of a second stroke of the 

 net with most species is rarely offered. 



I shall now mention the various families in systematic order, 

 giving the habitat of each. 



Stratiomyid.e : 44 species. — The larvte live in decaying 

 vegetable matter or in the earth. The flies appear on aquatic 

 plants ; their flight is slow. One genus, Bens, frequents woods 

 and flowers. 



Xylophagid.e : 4 species. — All rare ; sluggish flight. Larvae 

 feed on decayed wood. 



Tabanid.e : 20 species. — Found in woods ; flight rapid, 

 accompanied by a low hum. The females of many species attack 

 cattle, drawing blood by means of the large and powerful proboscis. 



BoMBYLiD^ : about 9 species. — Inhabit warm dry localities ; 

 appearing in summer ; flight swift and humming. Some larvse live 

 in earth, some are parasitic on lepidopterous insects. Rather rare. 



AcROCERiD^ : 2 species. — Globular, soft insects; venation 

 indistinct ; head nearly all eyes. Found on flowers or tree-trunks 

 on sunn}' days. Rare. 



ScENOPiNiD.E : 2 or 8 species. — Sluggish flies; found in 

 liouses, hot-beds, and about plants. The larvae live in rotten fungi. 



Thereyid^ : about species. — Found in sandy spots ; some 

 are carnivorous ; flight sudden and very swift. Tiie larvae live in 

 the ground. Mostlj' uncommon. The sexes difl"er in the colour 

 of their pubescence. 



AsiLiDiE : J species. — Large, powerful carnivorous flies ; 

 found in woods and pastures ; the larvae live in the earth ; flight 



