[19] 



COLLECTING AND PRESERVING INSECTS RILEY. 



FIG. 23. A Mosquito (Culex pipiens). a, 

 ailult; 6, head of same enlarged ; e, portion 

 of antenna of sanu-: /. larva; g, pupa. 

 (After Westwood.) 



The pupa3 are somewhat sluggish and the limbs and wings are en- 

 closed in a thin membrane which is expanded about the feet into bulb- 

 ous enlargements, giving rise to the name "bladder-footed" (Physo- 

 poda) applied to these insects by Burmeister. 



"Order DIPTERA (Hi?, twice; -r^;-,, wing) or Two-winged Flies. 

 The only order having but two wings, the hind pair replaced by a pair 

 of small, slender filaments clubbed at 

 tip, and called halteres, poisers, or bal- 

 ancers. 



"]So order surpasses this in the 

 number of species or in the immense 

 swarms of individuals belonging to 

 the same species which are frequently 

 met with. The wings, which are vari- 

 ously veined, though appearing naked 

 to the unaided eye, are often thickly 

 covered with very minute hairs or 

 hooks. As an order the Diptera are 

 decidedly injurious to man, whether 

 we consider the annoyances to our- 

 selves or our animals of the Mosquito, Buffalo-gnat, Gad-fly, Breeze-fly, 



Zimb or Stonioxys, or the injury to our 

 crops of the Hessian-fly, Wheat-midge, Cab- 

 bage-maggot, Onion-maggot, etc. There are, 

 in fact, but tAvo families, Syrphida? and Tachi- 

 nidfe, which can be looked upon as beneficial 

 to the cultivator, though many act the part 

 of scavengers. ISTo insects, not even the 

 Lepidoptera, furnish such a variety of curi- 

 ous larval characters, and none, perhaps, 

 offer a wider or more interesting field of in- 

 vestigation to the biologist. It is difficult 

 to give any very satisfactory arrangement 

 of these Two-winged flies, thong"!) they easily 

 fall into two rather artificial sections. These are: 1st, ^NEMOCERA, or 

 those with long antennae, having 

 more than six joints, and palpi hav- 

 ing four or five joints The pupa is 

 naked, as in the Lepidoptera, with 

 the limbs exposed. This kind of 

 pupa is called obtected. 2d, BRACHO- 

 CERA, or those with short antenna-, 

 not having more than three distinct 

 joints, and palpi with one or two 

 joints. The pupa is mostly coarctate, i. r., is formed within, and more 



FIG. 24. A Hawk-fly (Erax las- 

 tardi). a perfect insect ; b, pupa ; 

 larva shown at side. 



FIG. 25. A Flesh-fly (Sarcophaga carnaria, 



w . , rac n ). a, larva; &, puparium; ,-. 



adult insect with enlarged parts. 



