462 EXPERIMENT STATION RECORD. 



] iiart to 65 of water was found to be a far less effective agent against ail 

 stages tlian are soaps and other contact insecticides. 



In August, 1909, specimens of Aleyrodes nuhlfcra were received from Lemon 

 City, in Dade County, and later in ttie month it was found distributed in small 

 numbers from north of Lemon City to Buena Vista and to the Bay Front. 

 While the source of the infestation could not be determined, it was evident that 

 the fly had been present longer than 2 years, and possibly 5 or 6, judging from 

 its distribution. An examination made in September, 1909, to determine the 

 number of adult white flies that are bred and liberated in a large China um- 

 brella tree in Gainesville showed an average of 7.3 empty pupa cases per leaflet; 

 0.7 third-stage larvre; 12 fourth-stage larvse; and 4.2 pupse (an average for the 

 4 stages of 24.2) ; together with 1 dead larva. 



The author concludes that when a freeze sufficient to nearly or completely 

 defoliate trees occurs, the effects of such upon the white fly are about equiva- 

 lent to a fumigation with hydrocyanic-acid gas. 



Dipping- peach trees to control peach root aphis, M. A. Blake and A. J. 

 Farley (Neic Jersey *S/ffls-. Rpt. 1009, pp. 88-93, pU. 2).— Dipping experiments in 

 which lime-sulphur made by boiling 15 lbs. of stone lime, 15 lbs. of sulphur, and 

 50 gal. of water for 1 hour ; Scalecide 1 part to 16 of water ; and whale-oil soap 

 1 lb. to 3 gal. of water, were used, are briefly reported. 



" Three lots of 40 Elberta trees and 1 lot of 80 Elberta trees were selected for 

 the experiment. One lot of 40 trees had their roots thoroughly dipped in the 

 lime-sulphur solution, and another lot of 40 trees were dipped in Scalecide; 

 80 trees had their roots dipped in the whale-oil soap solution, and 40 trees were 

 reserved without dipping for check trees. After the trees were dipped they 

 were allowed to dry off slightly and were then ' heeled in.' . . . None of the 

 trees failed to grow except 1 which was dipi^ed in the whale-oil soap solution 

 and it is very doubtful if the dipping was a factor in the death of the tree. 

 All the trees made a very good growth during the season of 1908 and although 

 in some instances it was possible to detect differences in growth between the 

 various rows, these differences were not great enough on all the plats to permit 

 -of conclusive judgment by observation." In the late fall of 1908, after the 

 leaves had fallen, measurements were taken of the annual growth made by 

 each tree. 



" The 40 trees dipped in lime-sulphur made a slightly better average growth 

 than the undipped trees, but a comparison with the trees dipped in whale-oil 

 soap solution seems to indicate that it is likely that the lime-sulphur checked 

 the growth of the trees nearly as much as the aphis. The trees dipped in 

 Scalecide made a somewhat better average growth than the lot dipped in lime- 

 sulphur but some checking of growth is also apparently indicated. One average 

 of 40 trees dipped in whale-oil soap solution shows an average increase of 96.3 

 in. of growth over the undipped trees, and the average of the other 40 trees 

 dipped in whale-oil soap solution shows an average increase of over 200 in. of 

 growth over the undipped trees. This indicates that the dipping was of con- 

 siderable value." 



Some experiments on the chrysanthemum plant louse (Macrosiphum 

 sanborni) H. O. Marsh {[Bien.'] Rpt. Bel. Comrs. Agr. and Forestry Hawaii, 

 1909-10, pp. 160-112. pis. 3). — As a result of control experiments here reported, 

 the author recommends the use of a mixture of Blackleaf 40 IJ oz. and whale- 

 oil soap 4 oz. to 5 gal. of water. The larvffi and pupse of Leucopis nigricornis, 

 the most abundant natural enemy of this plant louse, are not injured by this 

 mixture. 



