Status of the Japanese Beetle in 1924

Abstract

The Japanese beetle, Popillia japonica, increased the area of its distribution during the summer of 1924 to include approximately 5,122 square miles. One infestation of beetles was found near Milton, Penna., a point about 150 miles distant from the main area of infestation. During the summer of 1924 there occurred a migrational flight of the Japanese beetles. About seventy-five per cent of the beetles on the wing at that time proved to be females and the flight lasted approximately four days. During this time the beetles swarmed through the business and residential districts of Philadelphia and outlying points, and it is believed that the majority of the beetles must have flown at least five to seven miles before reaching the city. During this time the insects were alighting on freight cars and vehicles of all kinds, and undoubtedly beetles were carried to some distant points. Methods have been devised for treating the soil to control the larvae which have been exceedingly effective. It has been possible to consistently treat the soil about the roots of nursery stock and obtain a perfect kill of the grubs over 18″ below the surface of the soil. It is now possible to treat golf greens infested by the grubs at a relatively small expense, since an outfit has been devised which eliminates the use of large mixing tank and reduces the labor cost nearly one-half in the application of the dilute emulsion. Progress has also been made in the control of the adult beetle. The finding of a constituent of the beetle's food plants which is highly attractive to the adult insect is being developed as a means of overcoming the repellency of the various poison sprays which have been used. Sufficient data were obtained during the past summer to indicate that the Tachinid parasite of the adult Japanese beetle, Centeter cinerea Aldrich, has become established over an area of approximately 12 square miles by the end of the season of 1924. The situation as far as the control of the Japanese beetle is concerned looks most hopeful. As conditions are at the present time the insect is probably as well, if not more effectively controlled, than are many of the more common insect pests.