Eleventh Report op the State Entomologist 231 



tirely depended upon for the complete destruction of the San Jose scale 

 when infesting orchards. According to Mr. Howard, an orchard in 

 Charlottesville, Va., which had been treated with the gas in March last, 

 under the skilled supervision of Mr. Coquillett, although " the operation 

 was as thorough as it could be made, a few of the insects survived the 

 treatment, as was shown by the receipt of living specimens late in the fall 

 from Dr. Hedges " {Insect Life, vii, p. 286).* 



Treatment of Nursery Stock. — It is believed that the hydrocyanic acid 

 gas treatment is reliable for disinfesting nursery stock of infested nurseries 

 previous to its distribution. Of course, all such stock found to have the 

 scale in abundance, should be promptly taken up and burned, but where 

 the scale is sparsely present or even where there is barely a suspicion of 

 its presence, it should, before shipment be subjected to the gas fumigation. 

 This is now being done in New Jersey and Long Island nurseries — in 

 some of them at least, and should be made a condition upon which any 

 further orders may be given or stock received from either of the infested 

 districts or others that may hereafter be discovered. 



The manner of treatment is the following : An air-tight box is made of 

 suitable size for the reception of as much stock as may be conveniently 

 treated at one time. The stock is placed therein and subjected for an 

 hour to the gas generated in it by the combination of three ounces of 

 water, a little more than one fluid ounce of commercial sulphuric acid, 

 and one ounce of 60 per cent, cyanide of potassium, to be placed in a 

 glazed earthenware vessel of the capacity of at least a gallon, in the order 

 above named. These amounts are for 150 cubic feet of space. It should 

 be remembered that this gas should not be breathed, as it is exceedingly 

 poisonous. 



Bibliography. 



The following references to publications upon Aspidiotus perniciosus are 

 given as an aid to those who may wish to learn more minutely of the life- 

 history and habits of the insect, or for information upon topics which 

 have been omitted from this Bulletin in order not to extend it to an undue 

 length, as for example : the parasites of the insect (see Insect Life^ vii, pp. 

 289-292); the possibihty of the Hmitation of its multiplication in its 

 northeastern range to certain portions of the State of New York and the 

 Eastern States (///., p. 292); its possible introduction through infested 

 Californian fruit (see Bull. 106 New Jersey Agr. Coll. Exper. St., p. 17, 



♦ Mr. Howard has since made personal examination of this orchard, and has found the gas 

 treatment inefficacious. The trees are again badly infested, while one result of the fumigation 

 has been to seriously injure the trees by causing the blackening and cracking of the bark. 



