278 KKPORT (IK OKFICE OK KXPKHIMKNT STATIONS, 



in«; (dice reduced (he imiiilter <>!' corn ritol-lice ((< (lie exleiit of 92 |)er 

 cent. A still more reiiinrUnhle result was oi)(:iiiied in another in- 

 stance, in w jiich a sin<;le treatment with the disk harrow applied as 

 soon as the i^ronnd was dry enonjiii to work re<hiced the nnmher of 

 corn root-lice in the fielil to the extent of S'.) \n'V cent. 'I lie ilisk har- 

 row is more eU'ective for this pnrpose than the ordinaiT hari-ow. 

 '^riie method develojK'd iiy the station is not only effective in destroy- 

 ing corn root-lice, but serves to put the soil in a better state of tiUajije 

 and shonkl therefore recommend itself to the farmer, 



THE HOP APHIS. 



Tn the hop-crowinfr repfions of the Pacific coast the hop aphis is 

 one of the most dreaded enemies of this crop. The California Sta- 

 tion " investigated this problem for the i)urpose of devisini^ practical 

 remedies. In one hop field an experiment was made in the use of 

 kerosene ennilsion and tobacco decoction combined. The toliacco 

 decoction was made by steeping tobacco stems and refuse for two or 

 three hours, usino; 1 pound of tobacco to 2 gallons of water. The 

 kerosene emulsion was made by dissolving 7i pounds of ordinary 

 laundry soap in 15 gallons of hot water and adding 5 gallons of kero- 

 sene oil. The emulsion and tobacco decoction Avere thoroughly mixed 

 and sprayed upon the hops. The mixture contained ?>4 gallons of the 

 kerosene emulsion for each 40 gallons of tobacco decoction. This 

 remedy was entirely effective in controlling the hop louse. Satisfac- 

 tory results were also obtained from a mixture of whale-oil soap and 

 quassia extract. In California there seems to lie no })ossible suc- 

 cessful treatment in Avinter for the hop aphis, Init by the use of the 

 washes just mentioned the hop aphis may be kept in check, so that 

 no winter treatment is necessary, 



BLACK FLIES, 



Black flies sometimes multiply to such an extent as to become a 

 serious pest to man and cattle. In New Hampshire ^ it was found 

 that the larvie of this fly, Avhicli live in running water, may be de- 

 stroyed by pouring a proprietary miscible oil into the water at the 

 upper end of the colonies of larva^. In some instances all of the 

 larvae in such colonies were destroA^ed Avithin tAventy-four hours. 

 The oil penetrates into the Avater and spreads (piite rapidly in all 

 directions. Stones remoA'ed from the bottom of the stream forty-, 

 eight hours after the application still had a thin film of oil on them. 

 In a stream 3 feet Avide 1 gallon of a proprietary miscil)le oil killed 

 off the larA'a? for a distance of one-eighth mile from the point of 

 application. 



a California Sta. Bui. IGO, & New Hampshire Sta. Bui. 112. 



