DIPTERA 859 



The members of this family were formerly included in the Sepsidag. 

 The family Piophilidas was monographed by Melander and Spu- 

 ler ('17). 



Family PSILID^ 



The flies of this family are of moderate size and slender. In many 

 of the species the antennae are very long and decumbent, but in others 

 they are of moderate length. The vibrissee are wanting; the costa is 

 interrupted near the end of vein Ri; and cells ist A and M are com- 

 plete and relatively large. Five genera including thirty-three species 

 have been described from our fauna. For a synopsis of the family 

 see Melander ('20 b). The following is our best-known species. 



The carrot rust -fly, Psila rosce.— The larva of this species infests 

 carrots, celery, parsnips, and parsley. In the case of carrots and pars- 

 nips the larvae perforate the roots in all directions ; their burrows are 

 of a rusty color, hence the common name of the insect. When celery 

 is attacked the fibrous roots are eaten off and destroyed. 



The family DIOPSID^ is represented in North America only by 

 the following species. 



The stem-eyed fly, Sphyracephala brevicornis. — This is a very 

 singular fly, which is found on the leaves of skunk-cabbage and the 

 foliage of other plants in shady glens. On each side of the head there 

 is a lateral process, upon which the eye is situated. The life-history 

 of the species is unknown. 



The family CAN ACEIDvE is represented in our fauna by a single 

 described species, Cdnace snodgrdssi, recorded from New Jersey. 



Family EPHYDRID^ 



These are small or very small, black or dark-colored flies, that 

 live in wet places. The subcostal vein is coalescent for the greater 

 part of the length with vein Ri, being distinct only at its proximal 

 end; cells M and ist M2 are not separated by a cross- vein; the hind 

 metatarsi are not thickened and are longer than the following seg- 

 ment ; the vibrissas are wanting ; and in some species the mouth cavity 

 is very large. 



Most of the species live about fresh water; but to this family 

 belong the "Brine-flies" the larvse of which live in salt or strongly 

 alkaline waters. These are common in pools about salt-works ; and in 

 the far West and in Mexico these larvee occur in the alkaline lakes in 

 countless numbers, and are washed ashore in such quantities that 

 bushels of them can be collected. They are gathered by the Indians, 

 who dry them and use them for food, which they call koo-tsabe, 

 accented on the first syllable. The best -known "brine-flies" belong 

 to the genus Ephydra. 



Still more remarkable are the habits of the larva of the petroleiim- 

 riy, Psilopa petrolei, which lives, feeds, and swims about in the pools 

 of crude petroleumi, which are numerous in the various oil-fields of 



