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JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 16 
which are used to supplement this treatment is a matter of conjecture. 
There is .evidence, however, that most of these treatments may just as 
well be discarded as applied by the average owner of boxwood, laboring 
under the popular misconception that because it worked for Mr. Smith 
under one set of conditions it should work for Mr. Brown under an 
entirely different set. There is no doubt that control could be secured 
whether the material used is molasses, rosin fish oil soap, tobacco ex¬ 
tracts, or any other efficient contact spray, if the time and frequency of 
applications is properly correlated with the emergence period and the vary¬ 
ing weather conditions. 
In southeastern Pennsylvania adults have been observed emergingas 
early as April 17th on imported stock from Plolland which had just been 
unpacked from crates and which doubtless had been kept at a warm 
temperature in transit. In 1921, emergence under natural conditions 
was first noted on May 1st, and in 1922 pupation was first noted on April 
18th and emergence on May 8th. The period of emergence seems to be 
regulated by seasonal temperatures, and doubtless must be preceded 
by a settled temperature of 70° to 80° F. for a period of two or three 
weeks. In the spring of 1920, which was late, the first emergence was 
noted by Hamilton 1 in the vicinity of Baltimore, on May 19th. 
Recent success with fumigation suggests this treatment as the most 
certain of accomplishing results, but the expense, as well as danger, 
incident to fumigation with hydrocyanic gas, and the limited period— 
when the insect is in the pupal state—in which it has been found to be 
effective will not warrant its use except in the case of very valuable 
specimen plants. The elements which are lacking in making the molas¬ 
ses treatment of more general value, cheapness and greater resistance to 
rain, are thought to be found, in the experience of the writers, in the use 
of a heavy emulsifying petroleum oil. Its capacity for entangling the 
adults and checking oviposition is fully as efficient as in the molasses 
treatment, as indicated from the results of our field experiments in the 
spring of 1922. . The product used is manufactured by the Sun Oil 
Company, and is free from any animal or vegetable fats. It has a 
Baume registry of 16 to 17 degrees and viscosity of 1200 at 70° F. 
The outcome of a number of preliminary experiments with various 
materials to ascertain their effect on the foliage of boxwood with a view 
to killing the larvae in the leaves or of causing the foliage to drop, was 
negative, but it was in the incidental use of this oil as a spreader for 
“Black Leaf 40” that its extremely viscous and adhesive properties were 
x Jour. Econ. Ent., Vol. 14, No. 4, August 1921, pp. 359-365. 
