148 DECIDUOUS FRUIT INSECTS AND INSECTICIDES. 



THE EtTBOPEAN FRUIT LECANIUM. 



(Lecanium corni Bouch6.) 



APPEARANCE OF THE INSECT. 



The insect heretofore generally known as the brown apricot scale 

 belongs to the subfamily of scale insects, the Lecaniinse, being naked 

 but with hardened derm, and differs from the San Jose scale and 

 European pear scale in that the horny covering of the full grown scale 

 is a part of the body of the insect, while in the case of the other species 

 mentioned the body is protected by a waxy covering made up from 

 secretions and the molted skins of the larvae. 



The adult female of the European fruit Lecanium is about one- 

 eighth to three-sixteenths of an inch long, three-thirty-seconds to 

 one-eighth of an inch wide, and about one-eighth of an inch high, 

 yellowish in color, marked with black. The older scales are shiny, 

 oval, convex, and often covered with a mealy pruinose deposit (see 

 PI. XII, fig. 1). 



PLAN OF WORK AND METHOD OF ASCERTAINING RESULTS. 



In the winter of 1909 an infested orchard near San Jose, Cal., was 

 selected and divided into 9 different plats of 14 trees each. Eight 

 plats were used for trying out various sprays, and the ninth plat was 

 left unsprayed for a check. 



It was planned to examine a number of twigs at intervals of two 

 days, two weeks, five weeks, three months, and ten months from 

 date of spraying for proportion of live and dead scales; also, to take 

 into account the action of the different washes on the trees and to 

 examine the fruit as to freedom from the sooty fungus. The effect 

 of the sprays l5pon the growth of lichens on the trunk and limbs 

 was also to be noted. Such a number of examinations was considered 

 necessary as some of the sprays were immediate in their action while 

 others acted over a longer period. 



APPLICATION OF SPRAYS. 



All of the plats were treated February 18 with the sprays indi- 

 cated below, using a single bent-disk nozzle (with one-eighth inch hole 

 in disk) on each rod, the pressure being maintained at about 200 

 pounds by means of a gasoline-power outfit. At this pressure the 

 lichens were thoroughly soaked. From 4 to 5 gallons of liquid were 

 used per tree and the work was very thoroughly done. 



SPRAYS USED AND METHOD OF PREPARATION. 



Plat 1, 6 per cent distillate-oil emulsion. — This was made after the 

 formula given in Bulletin 80, Part IV, Bureau of Entomology. A 

 concentrated emulsion was made by dissolving 30 pounds of fish- 



