348 
Parasites of Common Flies 
of 1915, 1916 and 1917 1 . The three seasons were very different in character. 
In 1915 June, August and September were the finest months; in 1916 the early 
part of the season was dull, July and the early part of August very fine and 
the remainder of the season wet and unsettled; in 1917 April was very cold, 
May and the early part of June very fine and the remainder of the season wet 
and stormy. 
A short summary of the weather conditions in each month is given in 
Table I. 
Table I. Showing the weather conditions during the fly seasons of 
1915, 1916 and 1917. 
1915 
1916 
1917 
March 
Very cold, last few 
days warmer 
Cold, windy and wet; 
rain fell on 23 days 
Very cold and windy; snow 
fell till end of month 
April 
Cold and windy, last 
few days fine 
Cold and windy till 21st; 
later fine, warm, no 
rain 
Frequent snow showers up 
to 12th; after 20th finer, 
but cold. “Coldest April 
for over half a century” 
May 
Bright and dry, but 
cold winds frequent 
Up to 16th dull and damp, 
after 16th very fine and 
warm 
Very fine and warm. 
“Warmest May for over 
half a century” 
June 
Very fine month 
“Coldest June recorded 
at Greenwich” 
Up to 17 th very fine and 
warm; later cloudy and 
frequent showers 
July 
Unsettled, many cloudy 
days; rain fell on 16 
days 
To 6th fine and warm; 7- 
25 dull, windy, fre¬ 
quent showers; 26-31 
very hot and fine 
Very strong wind almost 
every day; several op 
pressive days with thun¬ 
der 
August 
Mostly very fine 
To 13th very fine and 
hot; afterwards windy, 
rainy, unsettled 
“ Peculiar in the exceptional 
violence and duration of 
its gales” 
September 
Dull and windy early; 
later hot and oppres¬ 
sive; end cold 
To 20th rainy and dull; 
later fine 
Fine on the whole; 13 days 
of dull weather or heavy 
rain 
October 
Cold and stormy, few 
good days 
Very unsettled and rainy 
throughout 
Early part wet; later fine 
November 
Very cold 
To 8th rain and wind; 
later bright but cold 
Fine, but very windy to¬ 
wards end 
It will be seen by reference to Chart 1 that in 1915 flies were most abundant 
in August and September, in 1916 in July and the early part of August and 
in 1917 in May and June. In each year the curve recording the number of 
flies caught corresponds with the curve for the maximum temperature 
recorded in the sun. It is evident that the appearance of flies early in the 
season does not necessarily indicate a great abundance in the latter part of 
the season. 
1 These figures were obtained by adding together the maximum temperatures recorded daily 
and the numbers of the flies caught daily in each week and dividing the results by sev<in. 
