CHAPTER XXXIII 

 INSECTS AFFECTING CITRUS FRUITS 



Insect pests are among the most serious obstacles to the 

 successful growing of citrus fruits. In spite of the fact that 

 California growers spend more than half a million dollars 

 annually in fighting the scale-insects (Coccidce) in their orange 

 and lemon groves, the losses caused by these pests are still 

 enormous. It is estimated that the Florida orange growers 

 would receive annually at least one-half million dollars more for 

 their crop if the white-fly, Aleyrodes citri, could be exterminated 

 in their groves. 



As the attack on citrus trees is made chiefly by a few insects 

 that are closely related to each other, and hence are much alike 

 in the nature of their injurious feeding, and in their structure, 

 life-history and general habits, the remedies for the citrus 

 pests are less various than those used in the warfare against the 

 insect enemies of the deciduous orchards. Hence certain 

 generalizations can be made concerning insect attacks on citrus 

 fruits and concerning the remedies for them. 



The injuries are chiefly caused by sap-sucking insects of the 

 order Hemiptera. These insects, though small, are prolific 

 breeders, and when once allowed a foothold in a grove increase 

 rapidly to enormous numbers. They suck the juices from 

 leaves and fruits, causing the former to wilt and the latter to be 

 rendered unmarketable. As most of the citrus insects secrete 

 honey-dew, the sooty fungus, Capnodium, whose spores ger- 

 minate freely in this substance, frequently grows in a close 

 felted mass over the attacked leaves and fruits, not only 

 rendering them unsightly and disagreeably dirty, but actually 

 seriously hurting the tree by interfering with the functions of 

 the leaves. The fungus closes the stomata, or breathing pores, 

 in the leaves, and prevents the proper exchange of gases neces- 

 sary to the tree's health. 



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