324 KANSAS UNIVERSITY SCIENCE BULLETIN. 



Morphology and Biology of Simulium vittatum and its 

 Distribution in Kansas. 



On casual observation Simulium flies are about the size of 

 the common fungus gnats (Mycetophilidse) which we often see 

 on a piece of apple peeling or on decaying fruit. However, 

 upon closer examination they are found to be distinctly dif- 

 ferent both in form and color. These little flies are gray to 

 black in color and are from two to four millimeters in length, 

 depending on the species and sex. They have a conspicuously 

 prominent thorax, hump-backed in appearance, and their 

 heads are drawn down in front of them. This latter charac- 

 teristic adds to the prominence of their thorax, so much so 

 that they have received the popular name of buffalo gnats. 

 In the South they are called turkey gnats, in the North black 

 flies, and in Europe sand flies. 



Perhaps the most conspicuous characteristics of Simulium. 

 flies are their comparatively heavy cone-shaped antennae that 

 protrude from between the eyes at the base, diverging like a 

 pair of horns. They are about the length of the head, ten 

 jointed, with the joints closely articulated except the two basal 

 ones, which are differentiated. Other noticeable character- 

 istics are their relatively broad and slightly veined wings, 

 their prominent thorax, and the structure of their mouth parts. 



The latter to be seen well must be dissected and placed under 

 a compound microscope. These I shall describe further on in 

 the paper. At the time of emergence their eyes have a reddish 

 tinge. They have no ocelli. Compared with other flies of 

 their size the legs are thick and heavy set. 

 LIFE history — habitat. 



Nearly every one has observed mosquito wigglers in rain 

 barrels and pools of standing water, but unlike this habit of 

 mosquitoes, Simulium flies breed only in running water, such 

 as ripples and waterfalls. It seems that its aquatic larval 

 nature demands well aerated water if it is going to live and 

 complete its life cycle. For instance, if a Simulium larva is 

 placed in a vessel of standing water it soon dies, apparently 

 for the want of sufficient oxygen. When S. vittatum. is washed 

 from the rocks in shallow ripples into deep water it will drown, 

 unless it floats with the current to another ripple or waterfall 

 where it can attach itself to a stone or vegetation. 



