38 



tion to the pupal stage occurs, this stage differing but slightly from 

 the larval in appearance. The adults begin to appear by the middle 

 of March and continue to emerge through April. The eggs deposited 

 by this brood require about three weeks for development, hatching 

 into larvse from the middle of April to the 1st of May. The adults 

 of the second brood begin to emerge by the middle of June and con- 

 tinue to appear until the middle of July. Between the middle of July 

 and the middle of September a third brood is developed, the larvae of 

 which, hatching about the last of October, carry the insect through 

 the winter. The number of eggs laid by a single female is in the 

 neighborhood of twenty-five, and they are placed, by preference, upon 

 new leaves, but all of the plant is taken when the multiplication of the 

 insect makes it necessary. The young larva is active, resembling 

 closely the larva of a true scale insect. The life of the adult ranges 

 from ten to twenty days. 



The most satisfactory remedies for this insect, as demonstrated by 

 Messrs. Swingle and Webber, are the kerosene and resin washes. The 

 treatments may best be made during the winter, between December 

 and March, and again, if necessary, in May, and also in August or 

 early in September. Two or three applications may be made in the 

 winter. The application in August is made if the sooty mold is found 

 to be spreading to the fruit. Since the insect lives on the under sides 

 of the leaves almost exclusively, it is of prime importance that the 

 under surface be thoroughly wetted with the spray, and it is necessary 

 that the tree be opened up by pruning. Fumigation with hydrocyanic- 

 acid gas is also a ready means of destroying this insect. It is undoubt- 

 edly kept more or less in check by parasitic and predaceous enemies, 

 and is subject to attack by several fungous diseases, which may be cf 

 occasional value in preventing its undue multiplication. 



THE BXTST MITE OF THE ORANGE AND THE SILVER MITE OF 



THE LEMON. 



This mite {Phytojytus oleivorus Ashmead — fig. 33) is an enemy of 

 both the orange and lemon, affecting these fruits in a somewhat dif- 

 ferent way. For many years this mite was known only in Florida, 

 and its injuries were notable only in the case of the orange. It is 

 probably native to the Florida peninsula, possibly having originally 

 some food plant other than the orange. 



The lemon and orange groves of California were for a long time 

 entirely free from the attacks of this mite, but about 1889 some car- 

 loads of citrus trees were taken into California from Florida and 

 planted, without careful inspection, in the Rivera and San Diego Bay 

 districts. This shipment of trees brought with it, unfortunately, two 

 or three of the Florida scale insects, and also this rust mite, which has 

 gained a foothold in the important lemon districts about San Diego, 



172 



