60 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 139 



in the pupa, but the imaginal parts formed inside of them are short 

 and disappear. 



The mouth parts of the male mosquito are much simplified by the 

 great reduction of the mandibular and maxillary stylets and the entire 

 absence of a hypopharyngeal stylet. The male proboscis, therefore, 

 consists principally of only the labrum and the labium, but the maxil- 

 lary palpi are usually highly developed and may be much longer than 

 the proboscis (fig. 22 A). Mandibular stylets when present are seldom 

 longer than half the length of the proboscis and are usually much 

 shorter. Marshall and Staley (1935) report that they are present in 

 all genera examined except "Aedes and Ochlerotatus." These writers 

 found maxillary stylets to be present in representatives of all genera 

 examined, but the length is highly variable, even in species of the same 

 genus. The labium is a deep trough, as in the female, and ends with a 

 tapering median ligular lobe between the labella (fig. 22 F). It will 

 be recalled that the hypopharynx of the male mosquito is not separated 

 from the labium, as in the female. The hypopharynx thus retains in 

 the adult male the larval condition of union with the labium. The 

 male "labium" is, therefore, really a labiohypopharynx. The hypo- 

 pharyngeal component in Anopheles is identified by Vizzi (1953) as 

 a sclerotic plate on the floor of the labial gutter. In sectional figures 

 he shows the salivary canal in an apparent median thickening of the 

 plate. In Culex (fig. 22 F) the salivary duct (SIDct) is a thread- 

 like tube that traverses internally the floor of the labial gutter and 

 opens on the tip of the ligula, but it appears to be free in the labial 

 lumen. 



The cibarial pump. — The structure here termed the cibarial pump 

 lies just beneath the clypeus at the base of the proboscis, and is the 

 organ that sucks the liquid food up through the canal of the labrum. 

 The same pump is present in all Diptera and is the sucking apparatus 

 of other liquid-feeding insects, such as the Hemiptera. It has long 

 been erroneously called the "pharynx," and even some recent writers 

 continue to call it such on the pretext of not wishing to confuse stu- 

 dents. It is possible, however, that some students might prefer to 

 know the facts. The organ in question is entirely outside the mouth, 

 as no true pharynx could be, but admittedly it is difficult to understand 

 its anatomical status in the mosquito. We must therefore turn to 

 some other more generalized insect for light on the nature of the 

 preoral sucking organ, and for this purpose the cockroach will be par- 

 ticularly illuminating. 



In a vertical lengthwise section of the head of a cockroach (fig. 



