SIMULIUM : NORTH AMERICAN SPECIES 167 



crawl under the wings, and weakly birds often die from the irritation 

 of the bites and from the loss of blood. Even human beings are not 

 exempt, and in some parts of Brazil the species are so prevalent and 

 troublesome at certain seasons, that the natives are compelled to keep 

 fires burning in order to protect themselves. They are well known in 

 the Amazon District as 'pium', and in South Brazil as ' barrachudo'. 

 Fortunately they do not enter houses. 



BRUNETTI'S KEY TO THE INDIAN SPECIES OF SIMULIUM 



1. Thorax black, at most with dull reddish brown tinge occasion- 



ally ..-, 2 



Thorax distinctly reddish brown, with short reddish hair . rufithorax. 



2. Thorax with grey shoulder spots and a wide greyish band 



on posterior margin grisescens. 



Thorax ash grey with three narrow black stripes . . . striatum. 

 Thorax without either grey shoulder spots or posterior bands .... 8 



3. Abdomen destitute of any sign of yellow hair . 4 



Abdomen with short bright yellow hair, or with long rather 



shaggy brownish yellow hair ......... 6 



4. Hind metatarsus much incrassated, nearly as long and large as 



the tibiae metatarsalis. 



Hind metatarsus not so conspicuously incrassated, distinctly 



less in size than the tibiae .......... 5 



5. Antennae wholly black. Length 2jmm griseifrons.* 



Antennae reddish yellow at base. Length Ijmm. . . . rufibasis. 



6- Abdomen with normal short very bright yellow hair. ..... 7 



Abdomen with distinctly longer, shaggy brownish yellow hair, senilis. 



7. Abdomen with at least the first two segments yellowish, or 



brownish yellow ; often several segments so coloured . indicutn. 

 Abdomen all black aureohirtum. 



JOHANNSEN'S KEY TO THE NORTH AMERICAN SPECIES OF 



SIMULIUM 



1. Ground colour of thorax and abdomen deep yellow ...... 2 



Grey or black ; its hairs may be pale ........ 8 



2. ' Femora with black tip, length of fly 2 mm. 1 Mexico . . ochraceum. 

 ' Femora without black tips. Length 3 to 4'5 mm. Rocky 



Mountains fulvum. 



3. Hind tarsi with its basal joint partly yellow ; legs bicoloured .... 9 

 Hind tarsi unicoloured ........... 4 



4. Halteres dusky ; thorax not striped ......... 9 



* Halteres white or yellow ; the female with striped thorax and 



bifid tarsal claws ............. 6 



* Simnlium griseifrons, of which the female only is known, is probably S. metatarsale, 

 of which the male alone is recorded ; the broadly dilated metatarsus noted in the key is found 

 in most of the males of the genus. ' 



