368 DIPTERA. 



toadstools contain numerous Itirvne or maggots, as the young 

 of tiies are called, which must be kept in damp boxes. 



Flies can be pinned alive, without killing them b}' pressure, 

 which destroys their form ; and numbers may be killed at once 

 by moistening the bottom of the collecting box with creosote, 

 benzine or ether, or putting them into a bottle Avith a wide 

 mouth, containing cyanide of potassium. Minute species can 

 be pinned with very slender pins, or pieces of fine silver wire, 

 and stuck into pieces of pith, which can be placed high up 

 on a large pin. In i)inning long-legged, slender species, it is 

 advisable to run a piece of card or paper up under their bodies 

 upon which their legs msiy rest, and thus prevent their loss 

 by breakage. Of these insects, as with all others, duplicates 

 in all stages of growth should be preserved in alcohol, while 

 the minute species dry up unless put in spirits. 



In the genuine flies the thorax is highly centralized ; the 

 maxillce are covered by the labrum, and the labium is not pro- 

 vided with palpi. The females lay eggs from which the larva' 

 are hatched. They are also divided into the Nemocera, com- 

 prising those flies having long, thread-like, many-jointed an- 

 tenn.T, and embracing the higher families, i.e. the Culicida', 

 Tix^tilidce, Bihionido' and BJiyphidce ; while the remain- 

 ing families of this division are included in the Brachycera, or 

 flies with short antennjip, such as the 3fuscidw; etc. But the 

 fossil genera, Elcctra and Chrj'Othemis, discovered hj Profes- 

 sor Loew in the amber of the Tertiary formation, and a North 

 American genus of Xylopli agidw , and the genus Rachicerus, 

 liave intermediate characters combining these distinctions, 

 which are thus shown to be somewhat arbitrary. 



C'uLiciD.E Latreille. The family of ISIosquitoes or Gnats 

 have tlie mouth-parts very long and slender : the maxillae and 

 m.andibles are free and lancet-like. Figure 274 (A, larva; c, 

 its respiratory tube ; B, ]iupa ; f?, the respiratory tubes ; a, t^e 

 end of the al>domen, with the two oar-like swimming leaves, 

 seen in profile at B, from drawings made by Mr. E. Burgess,) 

 illustrates the transformations of a species inhabiting brackisli 

 water in the vicinity of Boston. The larva; remain most of 

 the time at the bottom feeding upon decaying matter, thus act- 



