494 Observations on Habits and Parasites of Common Flies 
placed in earthenware pipes half buried vertically in the soil. From 
these pipes very few flies emerged and neither eggs nor larvae were 
often noticed in this material, though both eggs and larvae of many 
species were usually present in large numbers in excrement from the 
shade trap II. 
Ages of flies visiting the various baits. 
Some direct evidence as to the age of the flies of the genus Lucilia 
visiting excrement and animal matter was obtained. All flies captured 
belonging to this genus were pinned, and it was early noticed that some 
were so newly emerged and soft that the chitin of the thorax gave way 
before the pin, rendering it almost impossible to obtain satisfactorily 
mounted specimens. In others the chitin was harder, and in many old 
specimens very hard. During part of July careful daily notes were 
kept as to the condition of the 1081 flies of the genus Lucilia caught 
in traps I, IV and VI. The very soft flies were recorded separately 
from the moderately hard and hard specimens During this period 
130 females, all hard, but no males visited the dark trap in the open 
baited with animal matter (VI) The open trap baited with animal 
matter (IV) was visited by 302 flies, 88 males and 214 females, of which 
88 (29 %) were soft, young specimens Of the males 36 (41 %) were 
soft and of the females 52 (24 %). The open trap baited with excre¬ 
ment (I) was visited by 649 flies, 298 males and 351 females, of which 
433 (66 %) were soft. Of the males 235 (78 %) and of the females 
198 (56 %) were soft. 
It is evident, therefore, that the very young specimens of both 
sexes are mainly attracted to excrement as a food, since of the 521 young 
flies caught 433 or 83 % visited traps baited with excrement and only 
88 or 17 % traps baited with decaying animal matter. At this period 
of the year the older specimens visit excrement and animal remains in 
the open in equal numbers, but old females only are attracted to decaying 
animal matter in dark receptacles. 
Judging from the scattered observations which were made in regard 
to blow-flies the same rule seems to apply to them. 
Flies visiting fruit. 
All the species of flies which visit excrement and decaying animal 
matter also visit ripe fruit in the late summer and autumn months, 
but not in the same proportions either as regards species or sexes. 
The most common species visiting fruit are C. erythrocephala, M. 
