682 Mold as an Insect Destroyer. [ November, 
When Pasteur, employed by the French government to inves- 
tigate the fatal malady that had attacked the silk-worm, made the 
discovery that the disease was caused by a fungus growth which 
he styled muscardine, that it could be imparted to healthy larve’ 
simply by crushing infected ones on their food, and that the dis- 
ease could be detected, by means of a lens, in the egg itself, and 
thus the good eggs separated from the bad, he saved from utter 
ruin thousands of French families whose main support depended 
on this industry. But he did more. Though he carried his 
researches no farther, others took up the investigation where he 
abandoned it, and the result of Dr. Bain’s experiments, continued 
for twelve years, seem to have established the fellowing facts: 
That the mold of the mash tub, known as yeast, the mold that 
infects flies and fastens them to our walls and windows, the com- 
mon mold of cellars and damp places, and the mold that attacks 
certain water plants are but different developments of allied spe- 
cies of fungi, and alike fatal to certain species of insects that are 
brought into contact with it ; and that the disease was developed in 
France by moist food, lack of ventilation and cleanliness, is prob- 
able, and though many were able to pass through all stages, their 
infected eggs spread the disease through the land, and in this 
way became epidemic. 
I have just had an unpleasant experience of the effect of mold 
in the loss of a full-grown imperial walnut larva that I had reared 
from its first molt. Its food was inserted in wet sand in a Cov- 
ered tub, and before I was aware, its droppings and food were 
covered with mold. Fresh food, a sun bath and change of quar- 
ters was of no avail; it refused food for four days, then dropped 
from its perch a moist discolored mass. In an article in the 
Canadian Entomologist (1877), 1 gave an account of a large colony 
of Callimorpha larvæ, a species by no means common generally, 
and of my failure to bring one larva in two hundred to the pupa 
state. They were all taken at maturity, like the French silk- 
worms, with a purging of whitish serum. The weeds on which 
they fed in the woods were also covered with their dried skins. 
The next year they were as rare as ever. In the spring of 1874, 
the shade trees of our town, Newport, Ky., were attacked by 
legions of small gray caterpillars, spinning up and destroying the 
foliage, and invading doorways in such multitudes that the house 
_ broom was in constant requisition. Fine shade trees were hewn 
