16 BULLETIN 245, IT. S. DEPARTMENT OF AGRICULTURE. 



that the larvicidal value varies with the amount of powdered helle- 

 bore used, but when applied at the rate of one-half pound or more to 

 8 bushels of manure it will be efficient. It is not known how helle- 

 bore acts as a larvicide. At present no information is available as 

 to whether it has any effect on the eggs or pupse of the house fly. 



The effects of the presence of fly maggots in a pile of manure is very 

 strikingly shown by comparing figures 2 and 3 of Plate I. The pile 

 treated with hellebore has remained normal in shape and appearance 

 (PI. I, fig. 3), while the maggots have worked the untreated pile 

 shown (PL I, fig. 2), the manure being finely divided and the 

 pile scattered by the feeding and migration of the larva?. 



The bacterial counts of manure in the cages (Table VI) treated 

 with 1 per cent sulphuric-acid extracts of hellebore showed no bac- 

 tericidal effects. 



The bacterial counts of the open piles (Table IV) did not show 

 any consistent action, either stimulating or bactericidal. During the 

 season's work nitrites and nitrates were detected only in open-pile 

 experiments 53, A, B, C, and D, which were treated with hellebore, 

 and it is therefore apparent that the hellebore extract is not toxic 

 to the nitrifying organisms in this environment. 



Three series of temperatures taken daily of control piles and those 

 treated with pyrethrum, pyridine, and hellebore further indicated 

 that there was no permanent injury to the bacteria present in the 

 piles treated with the last substance. In the first series the tem- 

 perature was 13° below the control on the second day, but on the third 

 day was again the same as the control. Neither of the other series 

 showed any depression of temperature at the start, and the piles 

 seemed to undergo a normal fermentation, indicating, as do all the 

 data, that the treatment with hellebore does not reduce the fertiliz- 

 ing value of the manure. 



The chemical data on both the cage and open-pile experiments 

 show that the manure was unaffected by the hellebore treatment. 

 When 1 per cent sulphuric-acid extracts were used in the cage experi- 

 ments at Arlington, a reduction in alkalinity due to the added acid 

 was found. It is, therefore, evident that powdered hellebore can be 

 applied, using one-half pound to 10 gallons of water, without injuring 

 the fertilizing value of manure as determined by chemical and 

 bacteriological examination. Furthermore, a laboratory test has 

 shown that hellebore readily decomposes in manure. A sample of 

 manure treated with hellebore at the rate of one-half pound per 

 8 bushels when tested microscopically and colorimetrically gave 

 positive results, but after 30 days' fermentation both were 

 negative 



The alkaloidal content of the commercial green and white hellebore 

 is known to vary from about 0.2 per cent to 0.!) per cent of total 

 alkaloids. 1 In Table IV, series 53, the hellebore used was of known 



1 DataobUincd from Insecticide Laboratory, Bureau of Chemistry, U. S. Department of Agriculture. 



