156 American Midland Naturalist Monograph No. 3 



double on III to V. Comb of eighth segment of six thorn-shaped scales; indi- 

 vidual scale with a long apical spine about three times the length of the stout 

 subapical spines. Siphon slightly inflated, about three times as long as basal 

 width; pecten of 3 to 6 widely spaced teeth, not reaching middle of siphon; 

 subventral tuft small, multiple, inserted at outer third of siphon. Anal seg- 

 ment longer than wide, completely ringed by dorsal plate; lateral hair double 

 or triple; dorsal brush consisting of a long lower caudal hair and a shorter 

 multiple upper caudal tuft on either side; ventral brush extending almost the 

 entire length of the anal segment; gills, 4 longer than the anal segment, pointed. 



DISTRIBUTION. — United States, Mexico, West Indies, Central and South 

 America. Southern States: Alabama (96); Arkansas (30); Florida and Geor- 

 gia (52); Kentucky (140); Louisiana and Mississippi (52); Missouri (1); 

 North Carolina (52); South Carolina (64); Tennessee (52); Virginia (49). 

 Other States: Arizona and California (2); Colorado (128); Delaware (106); 

 District of Columbia and Illinois (52); Indiana (76); Iowa (155, 156); 

 Kansas (79); Maryland (19); Massachusetts (180); Nebraska (178); New 

 Jersey (77); New York (52); Oklahoma (159); Pennsylvania (8); Te.xas 

 (108); West Virginia (52). 



BIONOMICS. — The females are fierce biters, attacking any time during the 

 day or night. This species reaches its greatest abundance in the Florida Ever- 

 glades and in the rice fields of Arkansas. In these areas it occasionally kills 

 livestock and at times makes it almost unbearable for people to remain out- 

 doors at night, or in shaded areas during the day. Horsfall (86) found that 

 the flight range of this species may be as great as nine miles in the rice fields 

 in Arkansas. The females lay their eggs on damp soil in depressions subject 

 to flooding by rainfall or overflow, particularly from irrigation canals in the 

 rice fields. Soil with rank low-growing vegetation seems to provide ideal ovi- 

 position sites. The larval period is relatively short, usually requiring only 4 to 

 10 days. The winter is passed in the egg stage. Breeding occurs throughout 

 most of the year in the extreme South, but is more common from May to 

 October farther north (4th Sv. C. Med. Lab. records, 1942-1944, unpublished). 



PSOROPHORA (GrABHAMIA) DISCOLOR (CoquiUett) 



Culex discolor CoquiUett, 1903, Can. Ent., 35:256. 



ADULT FEMALE. — Medium sized species. Head: Proboscis dark scaled, 

 except for a very wide median whitish-yellow band (width of band about equal 

 to half the length of the proboscis) ; palpi short, dark, the apices pale scaled. 

 Occiput clothed dorsally with narrow golden-yellow scales and erect forked 

 scales, the forked scales mostly dark but those of central region pale; occiput 

 clothed laterally with broad flat yellowish scales. Thorax: Integument of 

 scutum dark brown, clothed with fine narrow pale-yellow to pale golden-brown 

 scales. Abdomen: First tergite whitish scaled; remaining tergites almost entire- 

 ly whitish to pale-yellow scaled dorsally, more or less speckled with dark 

 scales; basal dack-scaled patches present laterally, each pair sometimes con- 

 nected dorsally by a narrow basal dark band. Venter pale scaled, frequently 



