Xo. 64] DIPTERA OF COXXECTICUT : MORPTrOLO(;^ 39 



channel may be prevented by a chitinous, valvular projection near the 

 entrance into the fulcral pump chamber. 



In the Xematocera, and certain leptids, tabanids, therevids and 

 asilids, a second food pump (called the oesophageal pump" by Peterson, 

 1916, or the post})harynx b}" Patton and Evans, 1929, etc.) occurs just 

 t caudad of the fulcral region. Possibly this pmn}) developed first, and 

 was later supplanted by the fulcral pump. 



Piercing or vulnerant mouth parts (as contrasted with the spong- 

 ing tA'pe, etc.) are of two principal types in the Diptera. In one 

 type of vulnerant mouth parts, which may be i-eferred to as the "sty- 

 letovulnerant"' type (since the stylet-like mandibles, maxillary galeae, 

 etc., are the principal piercing organs), the labium does not pierce, or 

 enter the wound. ^Nlouth parts of this ty])e occur in sucl! Xematocera 

 as the phlebotomine Psj'chodidae, the Ceratopogonidae, Simuliidae, 

 Culicidae, etc., and in the Tabanidae, certain Leptidae {Symphoro- 

 mylu^ etc.) etc., among the Orthorrliapha Braehycera. In a second 

 type of piercing or vulnerant mouth parts, which may be referred to 



ii as the *'labiovulnerant'' type (since the labium is the principal pierc- 

 ing organ), the labium enters the wound — largeh^ through the action 

 of the prestomal teeth. This type is largely confined to the Cyclor- 

 rhapha, and occurs in the stable fly, tsetse flies, etc. 



Some Xematocera, such as the Blepharoceridae, which attack 

 other insects, might be included in the ''styletovulnerant"" type men- 

 tioned above, and certain empids, asilids,* etc., among the higher Dip- 

 tera have the mouth parts modified in adaptation to their predaceous 

 habits, but these types need not be further discussed here, since their 

 mouth parts have been described in the general work on dipterous 

 mouth parts by Peterson (1916). It may be worth while, however, to 

 discuss very briefly a few of tlie most important representatives of the 

 two types of insects with piercing mouth parts mentioned above. 



In the mosquito type (Fig, 4, L and Fig. 3, E), the labium, //, 

 forms a trough in which the other mouth parts, with the exception of 

 the maxillary palpi, lie. The sides of the labrum curve downward, 

 'and their inflexed edges are approximated ventro-mesally to form the 

 food channel (which is formed by the labrum alone). The hypo- 

 pharynx, /;/?, which is traversed by the salivary canal, is situated be- 

 low the labrum, and is received in a trough formed by the maxillary 

 galeae, g^ while the mandibles, md^ lie along the sides of the labrum, Zr, 

 above them. When the female mosquito prepares to puncture the 

 skin, the labella, la^ of Fig. 3, E, are closely applied to it, and the 

 maxillary galeae, </, are the structures chiefly involved in opening the 

 wound, into which the other mouth parts are thrust, extending be- 

 tween the labella, Za, which serve lo guide the parts protruding be- 

 tween tliem. The labium does not enter the wound, but is bent back- 

 ward (or bowed) as the other mouth parts sink into the skin. 



In the tabanid type shown in Fig. 4, (j, the labium, which forms a 

 trough in which the other mouth parts lie, has been omitted from the 

 figure. The top and sides of the food channel are formed by the 

 labrum, Ir, and the floor of the food channel is formed by the over- 



*The hypopharynx apparently forms the principal piercing organ in the Asilidae. 



