28 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 



is nicotine dust. Since it is almost impossible to kill flea-beetles by 

 using arsenicals or other insecticides, the repellent method is an im- 

 portant control measure. 



In Europe there has been considerable experimenting with repel- 

 lents to keep beetle larvae, particularly white grubs, from attacking 

 the roots of plants. The odorous substances were usually worked into 

 the soil around the bases of the plants, but it is doubtful whether 

 much protection ever resulted. In France and Belgium crude naph- 

 thalene mixed with sand was used. In France three other repellents 

 were found more or less effective — first, residue of glue; second, 

 naphthalene and kerosene mixed with sawdust ; and third, crude oil 

 mixed with lime, plaster of Paris, and feces. In Germany sulphur was 

 worked into the ground around strawberry plants. In England 

 naphthalene was successfully used against wireworms in gardens, 

 and in Australia crude naphthalene was effective against wireworms 

 injuring sugarcane. 



McColloch and Hayes (40) have recently reviewed the methods 

 and enumerated the repellents used to protect germinating seeds and 

 roots and to prevent the invasion of the soil by underground insects, 

 particularly beetles. Numerous substances have been recommended 

 as repellents, including crude carbolic acid, turpentine, naphthalene, 

 paradichlorobenzene, creosote, coal tar, oils of lemon and tansy, kero- 

 sene, and phenol. They state that no satisfactory repellent has yet been 

 found which can be depended upon under varying conditions existing 

 in the soil. They believe that this subject needs further investigation. 



Since the Japanese beetle is fond of ripening fruit, particularly 

 apples and peaches, and since it is not advisable to spray early fruit 

 with arsenicals, ripening fruit should be protected by other means. 

 Therefore, much experimental work has been done to develop an 

 effective repellent to take the place of the arsenicals. Metzger and 

 Grant (54) have developed smudge candles, which, when lighted 

 and hung in peach trees, give off ill-smelling smoke for a period of 

 five to eight hours. The mixture, to be burned slowly without pro- 

 ducing a flame, was put in a wire-screen cylinder, 31 inches long and 

 2.25 inches in diameter. In conclusion they say that wood flour and 

 potassium nitrate, when properly mixed, form a satisfactory base for 

 smudges. The fumes from pine-tar oil, Dippel's oil (bone oil), and 

 a commercial mixture of chloronaphthalenes, when given off from 

 burning smudge candles, are definitely repellent to Japanese beetles. 

 Air currents in the orchard, however, prevented the repellent smoke 

 from giving satisfactory control of beetles on early peach trees. 



