8 NATURAL CONTROL OF WHITE FLIES IN FLORIDA. 



PARASITIC AND PREDATORY ENEMIES OF WHITE FLIES. 



So far as known, there is no true insect parasite of the citrus wliite 

 fly (Aleyrodes citri R. & H.) or of the cloudy- winged white fly {Aley- 

 rodes nuhifera Berger) in this country. Dr. Howard, however, has 

 recently recorded ^ the finding at Lahore, India, by Mr. R. S. Wog- 

 lum, of this bureau, of the exit holes of true parasites. In the exam- 

 ination of specimens of parasitized white flies, verified as Aleyrodes 

 citri by Prof. A. L. Quaintance, Dr. Howard has found dead speci- 

 mens of a minute aphelinine which he has described as a new species 

 under the name of Prospaltella lahorensis. 



During the course of these investigations, two species of Prospal- 

 tella — P. aurantii How., and P. citrella How. — and two species of 

 Encarsia — E. luteola How., and E. variegata How. — have been quite 

 thoroughly tested Avith abundant material as to their ability to par- 

 asitize the citrus white fly.^ 



In addition to the outdoor attempts at colonization in the event 

 of successful parasitism, laboratory observations were made upon the 

 behavior of many specimens of the first three species in the pres- 

 ence of larvae and pupae of the citrus white fly in all stages of devel- 

 opment. Only one incident of especial interest was noted. One 

 female specimen of Prospaltella aurantii showed a peculiar interest in 

 a plump wliite-fly (A. citri) pupa, and in addition to carefully exam- 

 ining it she spent several minutes in attempting to force her ovipos- 

 itor through the skin of the aleyrodid, apparently without success. 



With the exception of Encarsia variegata How., the parasites men- 

 tioned have not been tested as to their ability to parasitize the 

 cloudy-winged white fly. Encarsia variegata seems to confuie its 

 attentions entirely to Paraleyrodes persese even when the citrus white 

 fly and the cloudy-winged white fly are present in greater abundance. 



In case the Indian white-fly parasite {Prospaltella lahorensis) fails 

 to become established in Florida or proves unable successfully to 

 attack either of the two species of white fly under the conditions pre- 

 vailing in the Gulf coast region, the work of testing all procurable 

 aleyrodid parasites should be continued. Owing to the danger of 

 introducing hyperparasites, suggested by Dr. Howard's studies'* of 

 material reared from Aleyrodes coronata Quaintance, it appears ad- 

 visable to conduct work of this kind in greenhouses far from citrus- 

 growing regions. 



» Joum. Eeoii. Ent., vol. 4, pp. 131-132, February, 1911. 



» The first two species were reared from Aleyrodes coronata Quaintance, collected by Mr. E. M. Ehrhorn 

 In California and sent to the Orlando Laboratory through Dr. Howard. The third species was reared from 

 Aleyrodes fernaldi Morrill, collected at Amherst, Mass., and sent to the Orlando Laboratory by Dr. 11. T. 

 Fernald. The fourth species of parasite is of common occurrence in Florida, where it has an Important 

 economic role in holding in check a citrus-infesting white fly, Paraleyrodes persex Quaintance. 



* Proc. Ent. Soc. Wash., vol. 10, nos. 1-2, p. 65, 1908. 



