[19] 



COLLECTING AND PRESERVING INSECTS RILEY. 



The pupse are somewliat sluggish and the limbs and wings are en- 

 closed in a thin membrane which is expanded abou^t the feet into bulb- 

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

 poda) applied to these insects by Burmeister. 



"Order DIPTEEA ((5:'c, twice; ttts^owv, wing) or Two- winged Flies. 

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



•^^y^^^h^j,^^ 



Fig. 23. — A Mosquito (Culex pipiens). a, 

 adult ; b, head of same enlarged ; «, portion 

 of antenna of same; /, larva; g, pupa. 

 (After Westwood.) 



of small, slender filaments clubbed at 

 tip, and called halteres, poisers, or bal- 

 ancers. 



"IS'o 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 Linaided 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 Stomoxys, or the injury to our 

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

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

 in fact, but two families, Syrphidse and Tachi- 

 nidie, which can be looked upon as beneficial 

 to the cultivator, though many act the part 

 of scavengers. jSTo insects, not even the 

 Lepidoptera, furnish such a variety of curi- 

 ous larval characters, and none, x^erhaps, 

 offer a wider or more interesting field of in- 

 vestigation to the biologist. It is diflicult 

 to give any very satisfactory arrangement 

 of these Two-winged flies, though they easily 

 These are: 1st, I!^emoceba, or 



Fig. 24.— a Hawk-fly (Erax has- 

 tardi) . a perfect insect ; b, pupa ; 

 larva shown at side. 



fall into two rather artificial sections 

 those with long antennae, having 

 more than six joints, and palpi hav- 

 ing four or five joints The i)upa is 

 naked, as in the Lepidoptera, with 

 the hmbs exposed. This kind of 

 pupa is called oMected. 2d, Bragho- 

 CERA, or those with short antennae, 

 not having more than three distinct 

 joints, and x)alpi with one or two 

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



Pig. 25. — A Flesh-fly (Sarcophaga carnaria, 

 var. saracence). a, larva; 6, puparium ; c, 

 adult insect with enlarged parts. 



