r. S. D. A., B. E. Tech. StT. V2. Pt. V. Issued October 21, IW 



M1S( ELLANEOrS PAPERS. 



THE MORE IMPORTANT ALEYRODID.E INFESTING ECONOMIC 

 PLANTS, WITH DESCRIPTION OF A NEW SPECIES INFESTING 

 THE ORANGE. 



By A. L. QUAINTANCE. 



In Charge of Deciduous Fruit Insect Investigations. 



INTRODUCTION. 



Systematically the Aleyrodidse occupy a position between the Coc- 

 cicla? and Aphididse, two families of insects containing many serious 

 pests of agricultural and horticultural crops. Species of Aleyro- 

 dida? are, however, with, a few exceptions, not at present of especial 

 economic importance, though many of them occur in some numbers 

 on useful plants. Also, with few^ exceptions, so far as known the 

 injurious species of this family are not yet generally distributed over 

 the world, as are so many scale insects and aphides, possibly from the 

 fact that the Aleyrodida? feed exclusively on the leaves of their host 

 plants and are thus not so likely to be distributed in shipments of trees 

 and plants as if occurring on the twdgs and branches. When once 

 established in a locality an introduced species, as compared ^ith 

 scale insects, would disseminate more rapidly, since the adults of both 

 sexes are winged, though they are not strong fliers. 



The Aleyrodida? are most abundant in tropical or semitropical re- 

 gions, though species of Aleyrodes in the United States are fairly 

 abundant in the Transition zone. Species of Aleurodicus, however, 

 are almost exclusively tropical, and Avith one exception are known 

 thus far only from the Western Hemisphere, whence it is not im- 

 probable that this species was distributed. 



The family contains only two genera — Aleyrodes and Aleuro- 

 diciis — and 143 species have been described to date. The literature 

 dealing with these insects is so Avidely scattered that it has seemed de- 

 sirable to comment briefly on the species known to infest economic 

 plants, so that their introduction or dissemination may be better 

 guarded against. 



ECONOMIC PLANTS AND THE MORE IMPORTANT ALEYRODID.^ 



INFESTING THEM. 



Tobacco. — Tobacco' is attacked b}^ two species of A leyrodes — namely, 

 .1. nicotiana^ Maskell, from Mexico, and .1. tahaci Gennadius, from 

 (irreece. The former is apparently not of much economic importance, 

 as shown by the condition of infested leaves from Mexico. A. tahaci 

 is, however, more injurious, according to Targioni-Tozzetti, who 



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