117 



forcing- the hot material back into itself will convert it into a 

 creamy mixture, such that if it is left to stand in a cold glass the 

 oil will not come to the top. This is the stock kerosene emulsion, 

 and when diluted with about forty-five gallons of water it is ready 

 for use. When the dilution water is added the pumping- should be 

 repeated to facilitate thoroug-h mixing. 



Fig. 7. The Walnut Scale : n, b, female and male scales enlar,a;ed; 

 c, male pupa; d, f, male and female scales, natural size. 

 (Howard, U. S. Dept. Agriculture.) 



A cheaper and more efficient insecticide method for these 

 scales is fumigation with hydrocyanic acid g-as. For this an air- 

 tight inclosure is necessary, and in the nursery business this will 

 usually take the form of a fumigation house specially prepared for 

 the treatment of nursery stock. The precise method of procedure 

 in thi« case will be furnished on application to this office. 



Additional Nukserv Scales wintering partly or fully 



GROWN. 



Besides this group of four of what we may call the riiig-and- 

 nipplc scales, two peach scales are to be treated, when they occur 

 in the nursery, by the most summary processes. The peach 

 Diaspis, unknown as yet in Illinois, is circular in the female, and 

 very elong-ate in the male, with a rib or keel running lengthwise 

 down the center. The female is g-ray and not readily distinguished, 

 being frequently almost covered over by the outside bark of the 

 twig. The male scale is white and more conspicuous. The female 

 hibernates full grown, and the eggs are deposited early in May, 

 hatching- about the middle of that month. This is a very injuri- 



