162 



JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 8 



if left to reproduce without artificial hindrance they would soon be- 

 come injurious. In other words, the pests should be killed before they 

 do much damage to either the tree or fruit. The pests should always 

 be kept in such a state of subjection as to do little or no damage. In 

 case the various pests to citrus trees are permitted to become so abun- 

 dant as to cause damage, the profits which might be derived from arti- 

 ficial treatment, such as spraying with an insecticide, are, to a certain 

 extent, lost. The life history and habits of nearly all pests on citrus 

 trees are, fortunately, such that good and satisfactory results can be 

 obtained any time the spray is applied. While such is the case there 

 are times when it is opportune to spray. These periods come when the 

 largest percentage of the insects is in the youngest stage, which Is the 

 one most easily killed. 



The following spraying scheme has been used quite extensively for 

 three summers and has generally given satisfactory results. It must 

 be admitted, however, that no hard and fast scheme can be given, and 

 the number of sprayings depends to a large extent on the thoroughness 

 of the work. 



I. Paraffin-Oil Emulsions; Government formula 1-50 or 1 per 

 cent of oil — May. The main object of spraying at this time is to kill 

 the white fly, scale insects, and to a large extent rust mites, although 

 this treatment must not be relied upon to control the last. This spray- 

 ing should be given after the adults of the first brood of white flies 

 have disappeared and before the appearance of those of the second 

 brood. The fruit should be an inch or more in diameter when the 

 spraying is done. This treatment should be given before the beginning 

 of the rainy season, so that the beneficial fungi will take care of those 

 insects which are not killed by the spray. 



II. Lime-Sulphur Solution, 32° Baume, 1-50 to 1-75 — June to July. 

 The main object of this treatment is to kill rust mites and the oppor- 

 tune time for its application varies with the appearance of the maxi- 

 mum number of the rust mites. It should be applied before the mites 

 get very abundant and before any russeting appears. It will also kill 

 some scales and white flies, but is of little value for that purpose. 



III. Paraffin-Oil Emulsions; Government formula 1-50 or 1 

 per cent of oil — August 25 to October 31. This is the second spraying 

 for the white fly and scale insects. The object of spraying at this time 

 is to kill all the white fly larvae which are the progeny of the third and 

 last brood. It is this brood which causes nearly all the damage from 

 the white flies, and the earlier they are killed the better it is for the 

 tree. This spraying also comes after all the beneficial fungi have done 

 their work. This will also remove the sooty mold from the trees and 



