HOUSE FLIES. 15 
development and will pupate in the ground. A further objection is 
that during the summer months, when fly breeding is going on most 
actively, the agriculturist is also busy and can seldom spare the time 
or the teams to carry out such a program regularly. 
CHEMICAL TREATMENT OF MANURE TO DESTROY FLY MAGGOTS. 
The general practice is, therefore, to remove manure and keep it 
in heaps located as a rule very near the stables. How can fly breed- 
ing be prevented in such accumulations? As a result of recent in- 
vestigations it is now possible to point out two methods which are 
practical and effective. 
The first is the treatment of the manure pile with chemical sub- 
stances which will kill the eggs and maggots of the house fly. The 
Bureau of Entomology, in cooperation with the Bureau of Chemistry 
and the Bureau of Plant Industry, has conducted a series of experi- 
ments during the last two years in which a large number of chem- 
icals were applied to infested manure and observations made not 
only on their efficiency in killing the maggots, but also as to their 
effect on the chemical composition and bacterial flora of the manure. 
The object was to find some cheap chemical which would be effective 
in destroying the fly larve and at the same time would not reduce 
the fertilizing value of the manure. 
TREATMENT WITH HELLEBORE, 
Of the numerous substances tried, the one which seems best to 
fulfill these conditions is powdered hellebore. Some of the powdered 
hellebore in use is prepared from the roots of a plant which botan- 
ists know as Veratrum viride, and which is popularly known as 
Indian polk or itch weed. It is common in wet grounds and is of 
wide distribution in the United States. The European species of 
this plant, Veratrum album, however, furnishes the bulk of the sup- 
ply. Hellebore contains a number of chemical compounds known as 
alkaloids. Alkaloids are organic substances, of which quinine, mor- 
phine, and cocaine may be mentioned as examples, which act very 
intensely on the animal body. For the treatment of manure a water 
extract of the hellebore is prepared by adding $ pound of the powder 
to every 10 gallons of water, and after stirring it is allowed to stand 
24 hours. The stock mixture thus prepared is sprinkled over the 
manure at the rate of 10 gallons to every 8 bushels (10 cubic feet) 
of manure. From the result of 12 experiments with manure piles 
treated under natural conditions it appears that such treatment 
results in the destruction of from 88 to 99 per cent of the fly larve. 
Amounts of hellebore less than 4 pound to every 8 bushels of manure 
are not so effective, while stronger applications will, of course, give 
somewhat better results. 
