Carpenter et al.: Mosquitoes of Southern U. S. ?3 



simple on segments IV and V. Upper lateral hair (6) on segments I to III 

 long, plumose. Pecten as illustrated. 



distribution. — Along the Rio Grande River in Texas; Mexico, the 

 West Indies; Central America; and South America, south to Ecuador, Colom- 

 bia, and Venezuela. A collection, consisting of 131 adult specimens, was 

 taken at Key West, Florida by Dr. G. N. MacDonnell during 1904, and 

 reported by King (91). One fourth instar larva was colletced by Ernest Erb 

 at Boca Raton, Florida, during 1944 and reported by Carpenter et al. (35). 



bionomics. — The females are avid feeders on man and domestic animals. 

 The adults are nocturnal and commonly invade houses in large numbers; how- 

 ever, it has been observed that they usually leave houses before sunrise. Larvae 

 may occur in almost any collection of sunlit fresh or brackish water, whether 

 it be fairly pure or stagnant. A surface matted with vegetation furnishes ideal 

 conditions for its breeding in lakes and canals. It is occasionally found breed- 

 ing in artificial containers. 



MEDICAL importance. — Various workers have experimentally demonstrated 

 the infectibility of A. albimanus with Plasmodium vivax and P- falciparum and 

 it has been found infected in nature on several occasions. This species is 

 regarded as the principal lowland vector of malaria in Central America and the 

 West Indies. 



Tribe Megarhinini 



The tribe Megarhinini consists of large, usually brilliant-colored diurnal, 

 non-bloodsucking mosquitoes. The tribe includes the single genus Megarhinus. 



Genus Megarhinus Robineau-Desvoidy 



Megarhinus Robineau-Desvoidy, 1827, Mem. Soc. d'Hist. Nat. 3:403. 



The adults of the genus Megarhinus are daytime fliers and feed on plant 

 juices. The larvae are found in tree holes and occasionally in artificial water 

 containers where they feed upon other mosquitoes occupying the same breeding 

 places. The genus is primarily a tropical one, but its distribution extends into 

 the north temperate zone. 



Edwards (55) divided the genus Megarhinus into three groups, A, B, and 

 C. Groups A and B occur in the Americas, but group C is confined to the 

 Old World. Two species, M. rutilus and M. septentnonalis, occur in the 

 United States. 



SALIENT characters. — A dill t: Clypeus broader than long, front margin 

 slighdy trilobed. Proboscis rigid on basal half, flexible and strongly curved 

 downward and backward on apical half. Palpi of females vary in length in 

 different species from only about one-sixth to about two-thirds the length of 

 the proboscis. Scutellum evenly rounded, with a continuous row of setae. All 

 species large, usually with flat scales of metallic luster on head, thorax, abdo- 

 men, and legs. Squamae without a fringe of hairs. Spiracular brisdes present; 



