33 



NATURAL ENEMIES. 



At least one natural enenry is known of tne genus Balaninus, a 

 braconid parasite, TJrosigalphus armatus Ashrn., which develops 

 within the body of the larva of all the common species. A second 

 parasitic proctotrypid, Trichasis rufipes Ashm., has been reared from 

 acorns infested with Balaninus nasicus and Ilolcocera glandulella, 

 and it is quite likely to be a parasite of the chestnut weevils. 



METHODS OF CONTROL. 



It is greatly to be regretted that no very practical- remedy for 

 nut weevils is known or can be suggested at the present day other 

 than the early destruction of the ''worms" in the nuts and observance 

 of cooperative clean cultural and other methods, which will presently 

 be mentioned. Before discussing these methods it may be well to 

 preface a statement of the uselessness of ordinary measures employed 

 in the control of similar insects. 



UNSATISFACTORY METHODS. 



. Stomach poisons.— The peculiar structure of the mouth-parts of 

 these insects (very minute mandibles placed at the end of a rostrum or 

 beak as line as horsehair and longer than the body in the females) is 

 almost sufficient proof of itself that tbe adults do not feed on leaves, 

 but depend for their sustenance on the substance of the growing nuts 

 or inner husks, which they penetrate when making a nidus for the 

 deposition of their eggs. The first appearing beetles, with little doubt, 

 feed on the undeveloped very young nuts, and to a considerable ex- 

 tent on the juices within the husk. There is, therefore, no seeming 

 possibility of our reaching these insects at all by means of stomach 

 poisons, particularly as we are unable to place the insecticide where 

 the insects would be obliged to eat enough of it to kill them. 



Contact poisons. — Possibly contact poisons might have some effect, 

 but this is also doubtful, and such frequent applications would be 

 necessary, considering the long periods of these weevils in the adult 

 stage — from about the middle of July to the first of September and 

 even later — that this would not be profitable in any case. Again, 

 there is great difficulty in applying a spray so as to reach all portions 

 of a tree where the nuts are borne. Kerosene emulsion, sprayed on 

 the trees at the particular time when the insects are most abundant, 

 before they have deposited their eggs, might act to some extent as a 

 deterrent, but this is also doubtful. 



The water test of infestation.— Having serious doubts as to the effi- 

 cacy of an old-fashioned test as regards the difference between 

 "wormy" and healthy chestnuts, an experiment was made with com- 

 mon small chestnuts obtained from a street vender November 11. In 

 22104— No. 44—04 3 



