1916] ECONOMIC ZOOLOGY — ENTOMOLOGY. 157 



wards. These are retaiiiocl for a period of from one to three days in the brood 

 chamber, which is a dome-shaped cavity beneath the scale. They then emerge 

 and migrate at once to the underside of the leaves, where they settle, mostly 

 along the midrib and the larger veins. The first instar, which lasts about IS 

 days, is vegetative and the larvae show no sexual differentiation, but during 

 the second instar, which also lasts about IS days, sexual dilTorentiation is very 

 pronounced. At the end of this instar the female is very flat and circular, 

 while the male, which is flat and decidedly oval, is protected by a conspicuous 

 waxy structure called the pupariura. After the second instar the sexes follow 

 entirely different lines of development. 



" The female remains for one day upon the leaves after entering the third 

 instar, which is the final instar for this sex. During this day it secretes a thin 

 wax .scale, which protects it during the twigward migration. At the beginning 

 of this migration tlie female larva; abandon the leaves and pass to the basal part 

 of the new growth, where they make their final attachment within the area 

 of greatest illumination. They then commence a period of rapid growth, during 

 the first 11 days of which they develop their uniting color, which is a conspicu- 

 ous red band upon the middorsal line. At the time the dorsal band is com- 

 pleted the male migrates to the leaves, mates, and dies. The female after 

 mating starts a rapid growth, during which the mating colors and the larval 

 I'haracters are lost and during which vast quantities of honeydew are deposited. 

 By the end of the twentieth day upon the twig the female has assumed all the 

 iidult characters. After this, growth gradually slackens until the cold of the 

 approaching winter forces the scale into hil)ernation. In the spring growth is 

 resumed. Maturity is reached early in .Tune and the scale dies early in July, 

 after having lived about 13 months. 



" The male, which makes the second molt and passes all of its remaining 

 instars except the last day of the imago under the protection of the puparium, 

 loses its mouth parts at this time and lives during the remainder of its lil'e upon 

 nourishment taken in the first two instars. The third or prepui)al instar lasts 

 about two days and is a period of rapid metamorphosis, in whicli the larval 

 organs are replaced by the adult structures. In the fourth or pupal instar, 

 which lasts for about eight days, the adult organs reach their full development. 

 At the fourth and final molt the imago escapes from the pupal case but remains 

 for about two days under the puparium before emerging, when it migrates at 

 once to the twigs, copulates, and then dies, after having lived about 40 days." 



Mention is made of four attending ants, none of which benefit the scale to 

 any extent, of several predaceous enemies, and of a number of parasites. The 

 scale is heavily parasitized by Coccophagus lecanii, which was the most abun- 

 dant species reared in 1912, although (7. cognatus was also abundant, especially 

 in the fall. In 1913 C. lecanii was rare, while C. cognatus appeared in large 

 numbers and attacked the developing females in the spring, killing from 20 to 

 50 per cent of the scales. ApJiycus stomachosus was the most abundant parasite 

 in 1913, being more numerous than G. cognatus. 



Remedial work conducted during the first season was directed toward the 

 direct prevention of soot injury, which was found to be impractical. In the 

 second season sprayings were directed against the scale, seven groups of mate- 

 rials being tested. The first of the.se groups contained corn oil, rosin oil, and 

 gasoline, the two first named being very good treatments but injurious to the 

 trees, while gasoline was ineflicient but gave promise as a wax solvent and pene- 

 trant. The second group contained miscible oils which were found to be injuri- 

 ous when used in the winter at effective strengths but were used without injury 

 when applied in the spring before the swelling and the bursting of the fruit 



