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ment indicated that even greater dilutions might be used but the increased care needed to thoroly wet the insects tended to offset the economy in the use of the stock material. The best results with nicotine extracts, so far as permanent effects are concerned, were secured by combining them with arsenate of lead and bordeaux mixture.

Pyrox used at the rate of one pound to eight gallons of water killed the beetles and also served as a repellent.

Insectine did not control the cherry leaf-beetle.

Tanglefoot reduced the number of eggs deposited at the bases of peach and cherry trees.

RESULTS OF TESTS BY OTHER EXPERIMENTERS.

Experiments by Cushman 1 and Isley to develop efficient spraying methods were largely directed to testing arsenate of lead and nicotine sulphate, and the results of their operations were similar to those described except that somewhat better results were obtained with arsenate of lead in combination with molasses. They also tested crude carbolic acid emulsion, using the formula of 10 pounds fish-oil soap, i pint of crude carbolic acid and 50 gallons of water. This proved efficient as a contact spray but, as was the experience with nicotine sulphate, it lacked lasting toxic and repellent qualities.

CONCLUSIONS AND DIRECTIONS FOR CONTROL

MEASURES. In the light of the results of the foregoing experiments it appears that the cherry leaf-beetle can best be controlled on large cherry trees by spraying during the first week of June or as the beetles first appear, with bordeaux mixture (4-4-50) combined with either four pounds of paste arsenate of lead or two pounds of dry arsenate of lead. It is believed that paste arsenate of lime can be used with the bordeaux mixture in place of the arsenate of lead, but more experimentation is needed before it can be generally recommended. In spraying, the foliage should be thoroly covered on both the upper and lower surfaces. In addition to protection from several species of insects, another benefit from this treatment is the control of various diseases of fruit and foliage, which during some seasons are the cause of considerable apprehension among cherry growers. For young cherry trees, especially those that have been set not more than two years, jarring the beetles into sheets placed under the trees, followed by the destruction of the beetles, is a satisfactory method of control. This is especially recommended when infestation is severe since the small amount of foliage present on young trees makes it possible for the beetles to defoliate them before the insects succumb to the poison if sole reliance is placed on an arsenical. After the number of beetles has been reduced by jarring, an application of bordeaux mixture with arsenate of lead should render the trees immune to further attacks.

1 Loc. cit. pp. 19–24.

The protection of peach trees is a more difficult problem because of the great danger of injury to foliage from applications of bordeaux mixture and arsenate of lead. If large trees are attacked by numbers of the beetles the only recourse appears to be an application of arsenate of lead at the rate of 4 pounds to 50 gallons of water. To every barrel of the spray add two pounds of lump lime to neutralize any soluble arsenic present in the mixture. Inferior brands of arsenate of lead should be avoided. With young peach trees, jarring the beetles into sheets spread on the ground will greatly reduce the numbers of the insects, and if the insects tend to increase in numbers again, follow jarring with an application of arsenate of lead. Bordeaux mixture should not be used on peach foliage.

Nicotine sulphate (40 per ct. nicotine) may be employed effectively against the cherry leaf-beetle if trees are first thoroly sprayed and then treatment is directed to the beetles which drop to the ground. In the experiments with tobacco mixtures the best results were obtained when one pint of the nicotine solution was added to 60 gallons of water, altho a dilution of one pint to eighty gallons of water proved very effective. The advantage of using nicotine solution is that it can be used on peach trees without injury to foliage. However, it possesses several disadvantages, which are the cost of application, owing to the rather excessive amount used per tree, and the necessity of frequent applications during the dispersion period of the beetles. Failures on the part of the growers to combat the pest satisfactorily with nicotine solution were largely due to lack of thoroness in spraying and neglect to spray the insects after they had dropped to the ground.

The use of a soap-carbolic acid solution as described above is to be recommended with the caution that, while it has generally proven safe to foliage, injuries to leaves of cherry trees have been reported.

Experiments with a commercial coating composition known as Tree Tanglefoot for capturing the beetles before they lay eggs at the bases of trees indicates that this method might be of use in controlling the larvæ of the cherry leaf-beetle on bird cherry in parks or arboretums.

While a cooperative effort to clear much of the waste land of bird cherry about farms might at first seem advisable, further study has shown us that during ordinary years these do not harbor the beetles, presumably because the proper conditions for hibernation do not develop; and only during years of severe outbreaks do the trees become infested. It therefore appears to be a good practice to allow these trees to remain that their fruit may serve as food for useful birds.

All efforts in reforestation that succeed in re-establishing new timber tracts on the waste, cutover and abandoned land of the Alleghany plateau region of western New York and Pennsylvania will not only help in increasing a state and national asset, but incidentally they will reduce the number of bird cherry trees and bushes, many of which are too young for producing fruit. It is the seedlings that spring up in large numbers after every fire that furnish food for the hordes of cherry beetles which overrun cherry orchards during years when the normal supply of food is restricted.

ACKNOWLEDGMENTS.

In our efforts to determine the distribution of the cherry leafbeetle, we have corresponded with a number of entomologists and horticulturists who have had an opportunity to observe the species, or who have specimens in their private collections. The assistance rendered by them has been previously noted in this bulletin.

For extended notes on G. cavicollis and references to literature we are under obligations to

Prof. R. H. Pettit, East Lansing, Mich.;
Prof. H. F. Wickham, Iowa City, Ia.;
A. B. Walcott, Field Museum Natural History, Chicago, Ill.;
W. T. Davis, New Brighton, N. Y.;
C. W. Leng, New York City; and
H. E. Backus, North East, Pa.

The author is also indebted to W. F. Wight, Bureau of Plant Industry, Washington, D. C., and Prof. W.W. Robbins, Fort Collins, Col., for information relative to the exact boundaries of the range of P. pennsylvanica.

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