44 FAUNA OF MAYFIELD'S CAVE. 



species is found over the wall and roof more than the preceding species, 

 and is sometimes seen on the floor or under debris. It is occasionally 

 attracted to bait, near which it has been seen pairing. This is the only 

 species of Helomyzidae which I have ever seen to fly of its own accord. 

 It is often attracted to one's light and occasionally flies squarely against 

 the glass over the front of the lamp, while I have often heard it buzzing 

 about or felt it fly against my body. Its reaction to a light held steadily 

 upon it is uncertain, as it crawls toward the light as frequently as away, 

 and often fails to respond at all. When disturbed by bringing the 

 hand near or touching it, it is more likely to take wing than any of the 

 others of this family. I have not identified its larva nor determined its 

 food, more than to observe that it is attracted to bait sometimes. There 

 is some increase in its numbers in summer, but it never approaches 

 L. latens in abundance. 



A single specimen of this species was taken on the ledge outside the 

 cave in March. 



Leria serrata (Linnaeus). 



A few specimens of this species were found within the cave. It may 

 be more abundant than it appears, as it very closely resembles L. latens, 

 and among the abundance of the latter would not readily be observed. 

 Known from Europe. 



Leria fraterna Loew. 

 Monograph in, 1872, 51 (Alaska) . 



A single specimen was taken in January. Probably accidental in 

 occurrence. Known from Alaska, British Columbia, and New Hampshire. 



Baron Osten Sacken (Packard, 1888, 81) remarks: ' Blepharopterse 

 (Helomyzidae) are often found in caves, where they are said to breed 

 in the excrement of bats. ' ' Their presence and abundance in Indiana 

 caves bear out the first part of this statement. They congregate in 

 abundance in recesses and cracks and on the damper portions of the 

 wall, usually not very far above the floor, and are particularly abundant 

 under the edges of projecting ledges and at the top of low arches at 

 the side of the cave. 



Curiously enough, flies of this family are always more abundant on 

 the overhanging slopes than elsewhere. This is especially true of 

 0. fenestralis; to a smaller degree it is true of L. latens, and much less 

 true of L. defessa. 



The larvae of 0. fenestralis have been taken from bait, and L. defessa 

 is occasionally attracted to bait; otherwise no indication as to their food 

 has been found. Fly larvae and empty pupal cases have been found 



