59 



the spring the old leaves which have lived through the winter. Until 

 the adult, or winged form, appears in the spring, shortly after the 

 first of May, the insects are confined wholly to these leaves, and 

 there is no chance for them to spread to the new spring growth. 

 The old leaves are usually weak and spotted with rust, and the plants 

 are, on the whole, benefitted rather than injured by their removal. 

 They lie close to the ground, and their dark green color contrasts 

 sharply with the bright light green of the newer leaves. The ex- 

 pense of removing these old leaves will be lessened if it is clone in 

 connection with weeding, but in any case the expense will be trivial. 

 Experienced strawberry growers advocate setting new fields as early 

 in the spring as the ground can be worked to advantage, perhaps 

 between the middle of April and the first of May in this latitude. 

 Plants taken from the nursery for setting purposes will be freed from 

 this insect in direct proportion to the thoroughness with which the 

 old wintered over leaves are removed. 



If the adults are allowed to emerge and become scattered over 

 the leaves so that a second brood of larvae appears, the insect should 

 be held in check in the nursery by an occasional thorough spraying 

 with kerosene emulsion (one part in ten of water) or whale oil soap 

 (1.5- ounces Bowker's Tree Soap or 2 ounces Good's Potash Whale 

 Oil Soap to a gallon of water). The spray, in order to be effec- 



tive, should reach the under surface of ths leaves, and for this pur- 

 pose an underspray nozzle can be used to advantage. 



During the first week in May, 1902, the writer tried fumigation 

 of growing strawberry plants in order to determine whether nurseries 

 can be freed from the insect in this manner. While the results are 

 apparently not of much practical value they are nevertheless inter- 

 esting, as showing the effect of potassium cyanide and carbon bisulfid 

 on the larvae of Aleyrodes and on growing strawberry plants. 



In the experiments with carbon bisulfid, the liquid was poured 

 on to cotton and placed near the plant to be fumigated ; a bell jar 

 with dirt tightly packed around its base was used as a cover. In 

 the experiments with Potassium cyanide a large dry goods box, made 

 practically air tight with putty, was first placed over the plant to be 

 treated and made to set squarely on the ground, with loose soil all 

 around in position to be quickly packed against the sides. The box 

 was raised from one end and the potassium cyanide, wrapped in 



