THE SAN JOSE SCALE 803 



Treatment of Nursery Stoclc. — It is believed that the hydro- 

 cyanic 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 com- 

 mercial sulphuric acid, and one ounce of 60 per cent cyanide of 

 potassium, to be placed in a glazed earthenware vessel of the capac- 

 ity 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 per- 

 niciosus 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 informa- 

 tion 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 

 possibility of the limitation of its multiplication in its northeastern 

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

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

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

 p. 17, and Insect Life, vii, p. 167) ; the varieties of plums and 

 pears more liable to its attack (Bull. 106 — ante, p. 16); and its 

 natural enemies (id., p. 16). 



Comstock : in Kept. Commis. Agr. for 1880, pp. 304-5, pi. 12, 

 f. 7 (original description), 



