368 DIPTERA. 



toadstools contain numerous larvse or maggots, as the yoimp" 

 of flies are called, vvliicli must be kept in damp boxes. 



Flies can be pinned alive, without killing them 1)3- pressure, 

 Avhich 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 pinning long-legged, slender species, it is 

 advisable to run apiece of card or paper up under their bodies 

 upon which their legs may 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 highty centralized ; the 

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

 vided with palpi. The females lay eggs from which the larvse 

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

 prising those flies having long, thread-like, manj'-jointed an- 

 tennae, and embracing the higher families, i.e. the Culicidce, 

 Tip u Helm, Bibionidm and R It yp h i d ce ; while the remain- 

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

 flies with short antennae, such as the Muscidce, etc. But the 

 fossil genera, Electra and Chryothemis, discovered b^^ Profes- 

 sor Loew in the amber of the Tertiar^^ formation, and a North 

 American genus of Xylophagidce , and the genus Eachicerus, 

 have intermediate characters combining these distinctions, 

 which are thus shown to be somewhat arbitrar}^. 



CuLiciD^ Latreille. The famil}^ of Mosquitoes or Gnats 

 have the mouth-parts very long and slender ; the maxillae and 

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

 its respiratory tube ; B, pupa ; d, the respiratory tubes ; a, the 

 end of the abdomen, with the two oar-like swimming leaves, 

 seen in pi'ofile at B, from drawings made by Mr. E. Burgess,) 

 illustrates the transformations of a species inhabiting brackish 

 water in the vicinity of Boston. The larvae remain most of 

 the time at the bottom feeding upon deca3'ing matter, thus act- 



