HADLEY:JAPANESE BEETLE AND SHADE TREES 
49 
nourished trees and plants are more susceptible to attack than those in 
a healthy condition. Obviously, therefore, the first rule is that the health 
and vigor of shade trees and ornamentals should be maintained by proper 
pruning, fertilizing, and other appropriate measures. 
The foliage can be protected by maintaining a deposit of spray residue 
on all portions of the plant or tree subject to attack, during the few 
weeks that the beetles are flying. The spray largely repels the beetle 
and prevents extensive feeding, the protection being obtained pri¬ 
marily by making the foliage non-attractive rather than by poisoning 
the insects. To apply the sprays properly to shade trees and the higher 
ornamental shrubs, high-power sprayers and spraying equipment are 
absolutely essential. 
Timeliness and thoroughness in the application of the repellent 
sprays are very important. As a general rule, and especially in localities 
where the beetles are very numerous, the first sprays should be applied 
when the beetles begin to appear in the vicinity, before they become 
established on the trees or shrubs. In central New Jersey, the first 
application should ordinarily be made between the 20th and 25th of 
June; in other parts of the area, earlier or later according to the locality 
and seasonal conditions. In localities where the infestation is not so 
dense, the first application may if necessary be delayed until the beetles 
begin to appear on the plants to be protected, but if the infestation 
becomes heavy, it may be very difficult to prevent injury after the 
beetles have once commenced feeding. 
The foliage of shade trees and ornamental shrubs that are subject to 
attack by the Japanese beetle can be protected by spraying with 6 
pounds of acid lead arsenate and 4 pounds of wheat flour in 100 gallons 
of water, or with 6 pounds of acid lead arsenate and 1pints of light- 
pressed fish oil in 100 gallons of water. The lead arsenate spray being 
a stomach poison will also be of additional value in controlling other 
leaf-feeding insects. Sometimes people object to using arsenical sprays 
in close proximity to residences; in such cases, a lime and aluminum 
sulphate mixture, consisting of 3 pounds of aluminum sulphate and 20 
pounds of hydrated lime in 100 gallons of water, may be substituted 
but this spray is not as effective as the lead arsenate spray under con¬ 
ditions of heavy infestation. These spray residues adhere well to the 
foliage, but it may be necessary to make a second application 2 or 3 
weeks later after the initial treatment, to cover new growth and replace 
the deposit removed by rains. 
