C 292-]] 
As to the extraordinary increafe of this infed in 
May 1737, the fucceflion of fevcn or eight mild 
winters, which preceded that feafon, might, by pre- 
serving their eggs, give occaflon thereto. As they 
are one of the earlieft kinds, the exceffively warm 
May that year fo effedually hatched their eggs, that 
they all came to perfedion : Whereas the more or- 
dinary worms and flies, that make a later appear- 
ance, meeting with the fharp eaflerly winds that 
happened that fummer to blow during the months 
of July and Augujl , were in a . good meafure de- 
ftroyed j otherwiic it is poflible they too might have 
had an extraordinary increafe. 
However I own, my Lord, this reafon hath its 
objections, and doth not fully fatisfy me. There 
is fcarcely a year that is not remarkable for fame 
one kind of in feds or flies, when no colourable 
reafon can be afligned for it from any known tem- 
perament of the year, which might not as well fa- 
vour a great increafe of any other fpecies. Infeds, 
as well as fevers, are epidemical, and probably de- 
pend as much on a certain occult conftitution of 
the air, water, or earth. Nay, it is an opinion re- 
ceived by fome, that all peftilential disorders are 
nothing elfe than prodigious flights of invifiblc flies, 
of which each fort, according as the conflitution of 
the year aflifls ir, takes its turn to multiply from 
worms proportionably little, bred in putrid carcafes, 
efpecially after great battles, and being raifed from 
thence into the air, are wafted not only from one 
body to another, but even to diftant countries. 
Sydenham , and, if I miflake not, others, have ob- 
served, that the feafons immediately preceding thofe 
in 
