HADLEY:JAPANESE BEETLE AND SHADE TREES 
47 
THE JAPANESE BEETLE AS A SHADE TREE PEST AND 
ITS CONTROL IN THE EAST 
By C. H. Hadley, Bureau of Entomology and Plant Quarantine , United States 
Department of Agriculture 
The Japanese beetle (Popillia japonic a Newm.) continues to be an 
insect of much concern to those interested in tree protection, particu¬ 
larly in the eastern part of the United States. The beetle is not a pest 
of -woodlands or forests, but is often a serious pest of shade and orna¬ 
mental trees, as well as of fruit trees, especially in farming and suburban 
residential sections. 
Distribution. In considering the present distribution of the Jap¬ 
anese beetle, the entire area over which beetles have been found may be 
roughly divided into two zones or areas, namely, the area of general 
distribution and the area of isolated colonies. In the area of general 
distribution, beetles occur generally throughout, although the density 
of the beetle population varies more or less according to local environ¬ 
mental conditions. In some localities, beetles are rather scarce and of 
little economic importance; in others the population has built up to a 
point where severe damage to vegetation and crops occurs, while in still 
other localities the peak of infestation and damage has been reached 
and followed by a subsidence with comparable decline in the amount 
of injury caused and the relative economic importance of the insect. 
This area at the close of the 1938 season occupies approximately 15,000 
square miles along the Atlantic Seaboard and is roughly bounded by 
the following points: Lewes and Milford, Del.; Barclay and Baltimore, 
Md.; Delta, Harrisburg, Manheim, Hamburg, and Portland, Pa.; 
Andover and Pomp ton, N. J.; Suffern and Peekskill, N. Y.; and Ridge¬ 
field and Westport, Conn. 
The area of isolated colonies includes the states of Georgia, South 
Carolina, North Carolina, West Virginia, Ohio, Indiana, Illinois, Michi¬ 
gan, and the states to the east. In this area, the colonies or points of 
infestation are for the most part of a minor character, quite localized, 
and widely separated. 
Obvious tree injury is limited for the most part to those portions of 
the area of general distribution wherein the beetle population is rather 
abundant. However, instances of rather severe foliage injury have been 
noted at some of the older localized infestations in southern New Eng¬ 
land, where the beetle populations have built up to a considerable extent 
as a result of very favorable local conditions. 
