NO. 8 ANATOMICAL LIFE OF THE MOSQUITO — SNODGRASS 23 



them are scraped off by the combs of the mandibles. Accompanying 

 the opening of the mandibles, the epipharyngeal apparatus is pro- 

 truded by action of its muscles and its bristles remove the food 

 particles from the mandible combs. These freed particles and others 

 that may be adhering to the epipharyngeal surface are then collected by 

 the long basal brushes of the mandibles (fig. 5 D) and, with the closure 

 of the mandibles, are pushed into the mouth of the pharynx. Though 

 the mandibles and the maxillae close at the same time, the maxillae 

 open first and the mandibles following remove whatever particles 

 may be adhering to the maxillae, which lodge on the hypopharynx 

 and with the next stroke of the maxillae are thrust into the pharynx. 

 Large particles collected on the hypopharynx are broken up by the 

 toothed lobes of the mandibles, which strike on the hypopharynx like 

 hammers on an anvil. 



The pharynx, by muscular expansion of its walls, functions as 

 a sucking organ for drawing in a stream of water accompanying the 

 mechanically ingested food particles. A contraction then follows in 

 which the dorsal wall is deeply infolded by the action of the dorsal 

 transverse muscles (fig. 8 E), reducing the pharyngeal lumen to two 

 lateral channels containing the filter brushes (fb). At the same time 

 the water is driven toward the mouth and the food particles are 

 filtered out by the brushes. The water is then discharged through the 

 open angles of the mouth, goes above the mandibles and escapes past 

 the sides of the head. Schremmer made further experiments on a 

 Culex larva by impregnating the water in a dish with carmine particles. 

 After feeding by the larva, the carmine was found massed in the 

 brushes along the sides of the pharynx. When the pharyngeal brushes 

 have worked as filters for some time and have become well loaded, the 

 pharynx makes a strong contraction which suddenly removes the 

 carmine particles from the brushes and lodges them in small clumps 

 at the mouth of the oesophagus, into which they are finally taken. The 

 mosquito larva swallows no appreciable amount of water, its water 

 balance being maintained by the anal lobes. 



The extreme specialization of the mouth parts and the pharynx in 

 the filter-feeding mosquito larvae gives a striking example of how 

 independent of the adult structure an insect larva may become in its 

 adaptation to a new way of feeding. In various mosquito genera, 

 however, the larvae of some or all species are predaceous on other 

 small aquatic animals, particularly on other mosquito larvae. Notable 

 in this group are members of the subgenus Lutzla among the Culicini, 

 and of the genus Toxorhynchites. In these forms the mandibles are 



