FLIES. 411 



causing them to wither and die. A number collected in the last week of June hatched 

 about the 8th of July. 



The family Simulid^ comprises but a single genus and about sixty known species. 

 The flies are small and short, and resemble the species of the next sub-order more. 

 There are no ocelli, the thorax is without a transverse suture, the legs short, tibiae 

 without spurs, and the hind tibiae and the first joint of the hind tarsi are dilated. 

 They rarely exceed five or six millimetres in length. 



The larvffi all live under water, usually of mountain or running streams, and they 

 are interesting little creatures. They are soft-skinned, thinner near the 

 middle. They have a cylindrical head, and two pairs of eye spots. 

 On the first thoracic segment there is a foot protuberance with bristly 

 hooklets, and the end of the abdomen has several appendages for attach- 

 ment. They live on sub-aquatic stems of plants or on stones, where 

 they form for themselves elongated cocoons open above. In this upper 

 end the pupae ensconce themselves with the anterior part of the body 

 naked and free, from which extend eight or sixteen very long, slender, 

 thread-like breathing-tubes. The perfect insect escapes under water and 

 crawls to the surface. 



Many of the species are black, and known under the name of " black 

 flies " ; in South America some are called mosquitoes. But wherever 

 they are found they (or' rather the females, for the males are harmless) 

 are troublesome enough, and in places do much damage. 



The European species that is best known {Simulium columbaczense) 

 is most common in the regions of the Danube, especially towards the ^^°of^Simirff«m' 

 mouth, where their dreaded appearance in certain springs spreads dis- farSi.^^' ^^' 

 may and fear among both men and beasts. In some years, which fortun- 

 ately do not recur very often, many hundreds of cattle fall victims to their bites. 

 Wherever they bite they are said to cause not only a burning itching but also very 

 soon a painful hard swelling that may remain for a week or more. Many such bites 

 close together produce a severe inflammatory fever, and, in the more susceptible, 

 cramps. The flies seek parts of the body which are thinly clothed with hair, but 

 especially will they endeavor to crawl into the various passages, particularly the nose, 

 where they will be found in such great numbers at the death of the animal as to form 

 layers. 



In America an allied species yet unnamed is quite as troublesome in our Southern 

 States; it is called the "buffalo gnat." The following account has been sent the 

 writer by Mr. Broduax of Louisiana : " These gnats are found here in greater or less 

 numbers every year, but they only occur in such incredible quantities but rarely. 

 They dislike dark places, and are easily kept away by smoke — a fact that cattle and 

 horses very soon learn to avail themselves of. Animals when attacked by a large 

 number are driven frantic, and will seek to evade their tormentors by rolling in the 

 dust, rushing about, etc. They will at times be almost literally covered by the flies, 

 and in every case the ears are filled clear down to the tympanum, and so thickly that 

 they seem piled upon each other. An inflammatory fever with a high pulse soon sets 

 in, and the animal dies of cramps or convulsions, when the skin of the entire body will 

 be found to be covered with numerous small ulcers. A singular habit was noticed in 

 these insects. On one occasion (March 21) I observed a large, pear-shaped mass of 

 the flies hanging from a blackberry bush, measuring six inches in width and seven 



