THE ENTOMOLOGIST’S 
WEEKLY INTELLIGENCER 
No. 101.] ‘ SATURDAY, SEPTEMBER 4, 1858. [Price Id. 
THE HOT SUMMEK. 
The weather experienced in the pre- 
sent season, the heats of June, and 
the comparative cold of July, have 
attracted the attention of (because they 
have made themselves felt by) the 
most unobservant. 
The shoals of Edusa, Cardui, the 
sprinklings of Daplidice, Lathonia, the 
London habitat of the Humming-Bird 
Sphinx, — all betoken some abnormal 
state of weather; and Convolvuli , the 
offspring of our hot summer of 1846, 
is again eagerly looked for. 
The average mean temperature of 
June is but 60°; last year it rose 
above 62°, and this year to 64£°. 
That was the great forcing month of 
the year, for very soon afterwards the 
temperature fell below the average ; 
but this comparison of the mean tem- 
perature does not by any means con- 
vey a correct idea of the amount 
of scorching we actually underwent; 
owing to the clear and cloudless skies 
the days were hotter and the nights 
colder than they otherwise would have 
been; the cold nights tended to re- 
duce the mean temperature, the mean 
lowest temperature in June being 
actually 1£° below the average lowest 
temperatures of that month, — to balance 
which the mean highest temperatures 
were considerably above 81°, and almost 
reached 82°, being more than 10° above 
the average maximum temperatures of 
June. Here we see clearly and sta- 
tistically brought before us the cause 
of the sudden appearance of so many 
uncommon insects. 
It has been ascertained that the 
date of the flowering of any plant is 
proportionate to the amount of heat 
it has received, and M. Quetelet is of 
opinion that inflorescence is hastened 
in the proportion of the squares of 
the excess of heat above the freezing 
point, and that on receiving a certain 
amount of heat such a plant will 
blossom, and that “whether a plant is 
found in such and such a latitude, 
at such and such a height, in the 
open air or in a greenhouse, it is the 
temperature so measured that must be 
considered,” whence he deduces that 
“geographical causes have no influence 
but by the variations they cause in 
temperature.” It would be interesting 
to try and ascertain whether any par- 
ticular degree of heat be necessary 
to the production of particular species 
of insects. 
