BISULFID OF CARBON FUMIGATION. 



This treatnient of the melon aphis has been used successfully for 

 some time, and is valuable in small fields, but less profitable where 

 cucurbit or other crops are grown over large areas. It consists in 

 evaporating bisultid of carbon under tubs, or similar tight receptacles, 

 such as pails, buckets, or boxes. The chemical is employed at the 

 rate of a dram (about a teaspoonful) to each cubic foot of space: a 

 tablespoonful will serve for ordinary small tubs. This method of 

 treating the plant does not injure it, and if the tub fit tightly to the 

 ground, so as to retain the vapor of the bisulfid, all of the aphides 

 which are covered will be killed. This method may be followed suc- 

 cessfully in large fields if the grower be careful to watch the vines for 

 the first appearance of the insects, and to treat such hills as require 

 fumigation, removing and destroying plants that are badly afi^ected to 

 prevent the spreading of the insects to others.^ 



Cautiox. — In the use of bisulfid of carbon as a fumigant for aphides 

 the usual precaution should be observed not to expose the fumes to fire. 

 The operators must not smoke during this process! As the gas is 

 heavier than air there is no danger, if ordinary care is observed, that 

 the fumes will be inhaled b}^ human beings. 



HYDROCYANIC-ACID GAS TREATMENT. 



This gas, as has been demonstrated by Prof. E. D. Sanderson, can 

 be used in the field in much the same manner as the bisulfid of car- 

 bon, with wooden tubs or buckets. It has not, however, been adopted 

 b}^ growers and we do not recommend it. It possesses an advantage 

 over bisulfid of carbon in that the cover used in gassing need not fit 

 closely to the earth. On the other hand, it is decidedly more danger- 

 ous to human life and must therefore he handled ivith the greatest care! 



As a greenhouse insecticide this gas is a perfect remedy for aphides 

 and other small and soft-bodied insects. It is used where tobacco is 

 unsafe; for example, in violet houses, violets being especially subject 

 to '^spof after fumigation with tobacco. The method of applying 

 hj^drocyanie-acid gas is described in Circular No. 37 of this Office. 



PYRETHRL'M POWDER. 



Pyrethrum or buhach insect powder, administered divy with a pow- 

 der bellows to the lower surface of leaves, will kill the insects, altho 

 these sometimes do not appear to be affected at first. A second or 

 third application is sometimes necessary. This is an expensive rem- 

 edy and can not be used with profit on large fields or on plants with 

 large leaves, like squash. 



^' In New Jersey and Colorado many growers simply take out and bury such badly 

 infested plants as are noticed when the hills are turned for cultivation. 



