16 FARMERS' BULLETIN 851. 



With this idea in mind, it has been recommended that stable 

 manure be removed every morning and hauled out at once and spread 

 rather thinly on the fields. This procedure is advisable from the 

 point of view of getting the maximum fertilizing value from the 

 manure. Immediate spreading on the fields is said largely to prevent 

 the loss of plant food which occurs when manure is allowed to stand 

 in heaps for a long time. This method will be effective in preventing 

 the breeding of flies only if the manure is hauled out promptly every 

 morning and spread thinly so that it will dry, since it is unfavorable 

 for fly development in dessicated condition. Removal every three or 

 four days will not be sufficient. Observations have shown that if 

 manure becomes flyblown and the maggots attain a fairly good size 

 before the manure is scattered on the fields, they can continue their 

 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 tune 

 or the teams to carry out such a program regularly. 



CHEMICAL TREATMENT OF MANURE TO DESTROY FLY MAGGOTS. 



The general practice, therefore, is 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 inves- 

 tigations, it is now possible to point out two methods which are prac- 

 tical 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 in which a large number of chemicals 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 larvae 

 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 is popu- 

 larly known as Indian polk or itch weed. 1 It is common in wet 

 grounds and is of wide distribution in the United States. The 

 European species of this plant, 2 however, furnishes the bulk of the 

 supply. Hellebore contains a number of chemical compounds known 

 as alkaloids. Alkaloids are organic substances, of which quinine, 



1 Veratrum viride, * Veratrum album. 



