10 FUMIGATION FOR THE CITRUS WHITE FLY. 



tunately the list of food plants « is limited, and the greater number 

 of those thus far recorded is subject to infestation only when located 

 near or in the midst of heavily infested citrus groves. The food plants 

 which are of most importance in connection with the wliite fly control 

 are the chinaberry trees, privets, and cape jessamine, and these — 

 except for the last, in certain sections where grown for commer- 

 cial purposes — can be eradicated readily, or their infestation may 

 be prevented where community interests precede those of the indi- 

 vidual in controlling public sentiment. These food plants favor the 

 rapid dissemination of the wliite fly from centers of infestation and 

 their successful establishment in uninfested localities. They seriously 

 interfere with the success of fumigation, as well as of all other remedial 

 measures, by furnishing a favored breeding place where the wliite fly 

 can regain its usual abundance in a much shorter time than would be 

 the case if it were entirely dependent upon citrus fruit trees for its 

 food supply. The plants mentioned, together mth Citrus trifoliata 

 (except where used in nurseries), and all abandoned and useless citrus 

 trees should be condemned as public nuisances and destroyed in all 

 communities where citrus fruit growing is an important industry. 

 Where the destruction of chinaberry trees is impracticable for any 

 reason, they may be rendered innocuous by taking steps to prevent 

 their becoming heavily infested each year. This may be accomplished 

 by either defoliating each winter or by destroying entirely all privets 

 and cape jessamines and by thoroughly fumigating each winter all 

 citrus trees within a distance of 200 or 300 yards of each chinaberry 

 tree. 



SEASON OF THE YEAR. 



Fumigation for the white fly should be done during December, 

 January, and February, beginning not earlier than sixteen to twenty 

 days after the adults have disappeared, in order that all of the eggs 



a The complete list of food plants so far as known is as follows: Cittus (all varieties), 

 chinaberry {Melia azedarach and Melia azedarach umbraculiformis) , cape jessamine 

 {Gardenia jasminoides) , wild persimmon {Diospyros virginiana) , Japan persimmon 

 (D. hah), privets (Ligustrum spp.), Viburnum nudum, Ficus altissima, prickly ash 

 {Xanthoxylum clava-herculis) , cultivated pear {Pyrus sp.), cherry laurel {Prunus 

 laurocerasus), Primus caroliniana, lilac (Syringa sp.)-' Water oak {Quercus nigra) has 

 been reported as a food plant of the citrus white fly, but there is no definite record of 

 the insect reaching maturity on this plant, and the observations made in connection 

 with the present white fly investigations show that for practical purposes oaks may be 

 ignored as food plants of this species. Professor Gossard reports having observed 

 larvte of the citrus white fly on scrub palmetto (Sabalmegacarpa). The author once 

 observed larvte on the banana slu-ub { Magnolia fuscatum) but apparently none reached 

 maturity on this plant. Dr. E. A. Back has observed two live larvfe of the citrus 

 white fly on oleander {Nerium oleander). These plants (oaks, scrub palmetto, banana 

 shrub, and oleander) may be ignored absolutely as food plants unless it is proved 

 beyond doubt that it is possible for the citrus white fly to reach matmity on them. 

 The cultivated fig (Ficus), and the sweet bay ( Magnolia virginiana) have been reported 

 as food plants, but with little doubt these reports are erroneous. 



