132 INSECTS AFFECTING VEGETATION 



phid of carbon and the observance of clean orchard management 

 and other cultural methods. It may be well to preface the discus- 

 sion of these methods with a statement of the uselessness against 

 nut weevils of ordinary measures employed in the control of similar 

 insects. 



The value of bisulphid of carbon as a fumigant for chestnuts 

 infested by weevils is now fully established. Although at first 

 thought it would seem difficult for the gas to penetrate through shells 

 so firm and compact and kill the larvae, nevertheless a prominent 

 grower in Pennsylvania successfully uses the bisulphid, applying it 

 when the nuts are first harvested. The dead weevil larvae are at this 

 time so small that the average person would never detect their pres- 

 ence, while if they were permitted to develop they would soon de- 

 stroy the nut for food. Bisulphid of carbon has been used on the 

 largest chestnuts grown in this country, and, since a score or two 

 of larvae find shelter in a single nut, one can appreciate the desira- 

 bility of prompt fumigation. The grower mentioned uses bisulphid 

 of carbon at the rate of 1 ounce to a bushel of Paragon nuts placed 

 in a kerosene barrel of about 50 gallons capacity and covered by 

 sacking. After an exposure of about sixteen hours the nuts are 

 removed, the larvae being then practically all destroyed. Some 

 growers make a practice of plunging the nuts as gathered into boil- 

 ing water just long enough to kill the contained insects and yet not 

 injure the nuts for sale, after which they are dried before being 

 marketed. This may be profitably accomplished by using a large 

 sieve, which is filled with nuts, dipped in the water, and removed in 

 about five minutes. 



Different methods are emplo3 7 ed in drying. A good way is to 

 place the nuts in the sun and agitate them occasionally by stirring 

 or shaking in a bag until thoroughly dry, because if moisture re- 

 mains unevaporated it is apt to form mildew when the nuts are pre- 

 maturely packed for shipment. 



Nuts for planting should not be scalded, and care should be 

 taken not to cook the kernels of nuts intended for sale. Some 

 growers claim that the hot-water treatment is objectionable because 

 the nut-shells lose a certain degree of polish, rendering them less 

 desirable for market. Infested nuts can be subjected to a tempera- 

 ture of between 125 F. and 150 F. without injuring them for food 

 or for seed, and this will effect the destruction of the larvae within. 

 Some growers of chestnuts destroy the weevils by kiln-drying. 



Cold storage has been employed and is successful in arresting 

 the development of the larvae. The appearance of the nuts is 

 scarcely different from that of those not so stored, but nuts thus 

 treated and submitted to the writer after becoming dry were deficient 

 in flavor, having an acrid and moldy taste. A crude form of cold 

 storage has been successfully followed by a Virginia grower. It 

 consists in placing nuts in the earth under the shade afforded by 

 his house, where the soil temperature, after the nuts are gathered, 

 does not exceed 50. Since most insects are inactive below 51 



