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JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 16 
showed no injurious effects. It was not possible to try the effect of 
cyanogen chloride on young growing plants. There was very little 
evidence of the formation of either free chlorine or chlorine dioxide 
with a mixture of four parts of sodium cyanide to one of sodium chlorate 
and it is thought that this ratio could be very safely used even against 
young growing plants. 
Scientific Notes 
Do Rats Eat Mealybugs? Several observers have noted that where mealybugs 
(.Pseudococcus spp .) occur on sugar cane in some tropical countries stalks will be found 
with the leaf sheath gnawed through in one or two places and the mealybugs which 
were on the stalk underneath no longer there. An entomological friend, though he 
had not seen any animal doing this work, assumed that it had been done by rats, 
which he thought gnawed through the leaf sheath to feed on the mealybugs. A 
bulletin has now been issued by another worker in another country giving credit to 
rats for this aid in control, but again the rats have not been seen in the act. 
As far as I know rats may feed on mealybugs, but at Mercedes, Cuba, on Sep¬ 
tember 12th, 1918, I noticed the large reddish ants common in Cuba carrying mealy¬ 
bugs away in their mandibles through holes in the leaf sheaths which they had un¬ 
doubtedly gnawed. Specimens of the ant were afterwards determined by Dr. 
W. M. Mann as Atta insularis Guer. I have the specimens before me with the note 
which I made at the time. 
While the matter is perhaps of little economic importance, it might be just as well 
not to credit rats with a partial control of the sugar cane mealy bugs until more 
definite observations have been made. It might be mentioned that though mealy¬ 
bugs occur on sugar cane in Louisiana this gnawing of the leaf sheath has never 
been observed. Rats are present, but large species of ants are not. 
T. E. Holloway, U. S. Bureau of Entomology 
Colorado Potato Beetle in France. The readers of the Journal may be interested 
in the recent outbreak of the Colorado potato beetle in France, reported in a special 
number of the Revue de Zoologie Agricole, published in August 1922. The paper is 
entitled, “Le Doryphore. Chrysomele nuisible a la pomme de terre ( Leptinotarsa 
decemlineata Say),” by Jean Feytaud. This beetle was discovered on June 9, 1922, 
at Taillan in the Department of Gironde and was later found rather widely scattered 
throughout the department in the general vicinity of Bordeaux. It is believed to 
have been introduced accidentally in importations from America in 1919 or 1920. 
An interesting feature is the fact that within five weeks after discovery an emerg¬ 
ency appropriation of five hundred thousand francs had been made available for con¬ 
trol measures and that the former law, which refused indemnity to the owners of 
fields destroyed, had been amended in this respect. Within the same period ex¬ 
tensive machinery has been organized for control measures, including departmental 
committees of defense. 
