6i 



very little difference between the strength of these gases required to 

 kill the young of this insect and the strength that will injure the 

 •growing plant. Experiments numbers 10 and n seem to indicate 

 that as regards the killing of the insect without injuring the straw- 

 berry plant, a small amount of carbon bisulfid for a long time is 

 better than a large amount for a short time. 



Tests of the use of Potassium cyanide for the strawberry root 

 louse by Powell and Sanderson of Delaware, and also by Johnson 

 (Fumigation Methods, p. 14S), show that two-tenths of a gram of 

 KCN' is satisfactory when properly handled. The plants are taken 

 from the nursery, freed as much as possible from dirt and moisture, 

 and loosely packed upon trays in the fumigating box or room. 



To determine the effect of this treatment on the eggs of the 

 strawberry Aleyrodes, a large number of strawberry leaves with hun- 

 dreds of the insects' eggs attached to their under surfaces were treated 

 in a fumigating box, using .2 gm. KCN for twenty minutes. The 

 result was that none of the eggs hatched, although conditions in the 

 laboratory were favorable, as eggs on untreated leaves invariably 

 hatched under similar conditions. This shows that when strawberry 

 plants are treated according to the above method for the root louse, 

 the treatment will also be effective for the Aleyrodes when present. 



2. In the Field. This is the most difficult place to treat the 

 strawberry Aleyrodes. If they become very numerous in the fruit- 

 ing or newly set beds, and require treatment, the best that can be 

 recommended at present is to spray with an underspray nozzle as 

 described for the nursery. 



BIBLIOGRAPHY OF ALEYRODES PACKARDI 



MORRILL. 



1. Aleurodes vaporarium, Packard, Am. Nat., vol. iv, p. 686 



(i8 7 i> 



2. Aleurodes vaporarium, Packard, Guide to Study of Insects, p. 



712 (1883). 



3. Aleurodes sp., Forbes, 13th Ann. Rept. Insects of 111., p. 98 



and I (1883).* 



* Page 9S footnote, and page 1 Addenda and Corrigenda, " undescribed species," 



