Gr. S. GtRAHAM-8mITH 
485 
the season. Owing to the carnivorous habits of its larva this insect is 
an important agent in limiting the numbers of other flies (p. 503). 
Polietes lardaria occurred in moderate numbers in June and in the 
autumn. In both 1914 and 1915 it was very scarce in July and August. 
Ophyra leucostoma was abundant from June to October, the greatest 
numbers occurring in August. 
The males of F. canicularis entered the house in considerable numbers 
from May to October. 
The last curve shows the combined seasonal distribution of all the 
species caught in the various traps. 
Numbers of flies caught in traps. 
In rapidly identifying large numbers of flies mistakes are unavoidable, 
but the figures given in Table III fairly represent the distribution of 
the common species which were caught in these traps throughout the 
season. Under the heading of small Anthomyidae certain small flies 
not belonging to that family are probably included. The more un¬ 
common species of larger flies, which only occurred in very small numbers, 
are omitted except in trap I. The very small species, capable of getting 
through the mesh of the net, have not been taken into consideration. 
During the season 105,373 flies were caught in traps baited with 
excrement and animal matter. Traps in the open baited with excre¬ 
ment (39-5 %) and decomposing animal matter (37-6 %) attracted 
almost equal numbers. Dark receptacles in open situations caught 
smaller numbers (excrement, 10-6 %; animal matter 5-9 %), while 
traps in shady places attracted few flies (excrement, 3-6 %; animal 
matter 2-4 %), a large proportion of them relatively unimportant 
Anthomvids. 
In this country it is desirable therefore to place all receptacles for 
garbage, manure, and refuse in the most shady situations available so 
as to attract as few flies as possible. 
Some interesting information may be obtained by studying the 
records from comparable traps, I and IV, II and V, and III and VI, 
baited respectively with human excrement and decaying animal matter. 
Traps I (excrement) and IV (animal matter) in open situations. 
In April small numbers of freshly emerged flies were attracted to trap I, 
but none to trap IV, and in May when flies were emerging in large 
numbers six times as many visited trap I as visited trap IV. From 
June to October, except in August when larger numbers visited trap IV, 
