46 



FAUNA OF MAYFIELD'S CAVE. 



Via, 10.— Pupa of Ltmosina lenebranim. 

 Ventral view. X 20. 



very rapidly. This brings about a great increase in their number near 

 the mouth of the cave and to some extent as far back as "17," but 

 beyond that or at least beyond the mound, where the passage is subject 

 to very little change in temperature, they breed in about equal abundance 

 at all seasons and their number remains about constant throughout the 

 year. In the spring the earth from "4" to "6" where not too hard 

 becomes worked up and the pupal cases of this species are abundant in 

 the soil, on the wall above, on rocks, and everywhere about. The flies 

 themselves are extremely abundant, crawling through the loose soil and 

 over the walls. During June, 1905, an estimate of the numbers of these 



flies on the wall near the floor at 

 "6," where they were about 

 equally abundant for considerable 

 areas, placed their number at 75 

 to 100 to the square foot. This 

 is the extreme in abundance. But 

 at any season and in any part of 

 the cave, except near the mouth 

 in winter when the temperature 

 is low, these flies congregate in 

 numbers and are observed pairing 

 near any organic matter as soon 

 as putrefaction begins. 



The larvaa appear very soon 

 and in immense numbers upon any 

 organic matter left in the cave. 

 The larvae pupate in about two 

 weeks. The pupae are embedded 

 in the decaying matter usually, 

 but sometimes are seen on the sur- 

 face or fastened to a rock or other 

 object if quite near where the larvae feed. The adults emerge from the 

 pupae in about a week. Figs. 10, 11, and 12 represent pupae of this species. 

 As Blatchley (1896, 190) observed, these insects leap rather than fly when 

 disturbed. In escaping they crawl and leap a few inches, using their 

 wings to aid them, but never take an extended flight, even when tor- 

 mented and continually disturbed for some time. They do not move 

 very rapidly, but are much more active than the species of Helomyzidas 

 and respond more quickly to a stimulus. When a stone under which 

 are numbers of these flies is turned over they hop and crawl rapidly 

 away, apparently more rapidly when a bright light is thrown upon 

 them; however, when a light, as a candle, is left among them when they 



Fig. 11.— Pupa of Hmoaina tenebrarum. 

 Side vlew.X 19. 



Pig. 12. — Pupa of lAmosinatenebrarum, 

 Dorsal view. X 19. 



