30 



PARASITIC I'l'OX ALEYRODES CITRI. 



DISCOVERY. 



In September, 1907, Prof. P. H. Rolfs, when visiting the orange grove 

 of Mr. F. Wills at Sutherland, Florida, noticed that a great many larvae 

 of Aleyrodcs citri were dead or dying. None of the known parasitic fungi 

 were to be seen, but by the use of the hand lens a whitish fringe could be 

 noticed growing from the edges of the larvae. Specimen leaves were 

 brought back to the laboratory on September 13, and on microscopic ex- 

 amination, the larvae upon these leaves were found to be diseased by a 

 species of Microcera. Leaves sent in by Mr. Wills on September 26, were 

 found to have even more abundant fungus, and nearly all the larvae were 

 dead. Orange leaves sent in from Manatee a few days later were also 

 found to bear larvae infected with the same fungus. This Microcera has 

 since been found at Largo, Bayview, and Safety Harbor by the author, and 

 has been brought in from Orlando, DeLand and Leesburg by E. W. Berger. 

 A preliminary notice of this fungus was published by 

 the author in Press Bulletin 68 of the Florida Experiment 

 Station, "A Xew \Yhitefly Fungus". This fungus presents 

 a fringe of delicate white hyphae growing outward from 

 /j the edges of the larvae (Plate VI, Fig. 41). These hyphae 



at first bear one-, two-, or three-celled conidia, which are 

 oval to fusiform in shape (Fig. 16). Afterwards there are 

 formed on the edge of the larvae 

 pinkish spore-masses, which are 



Kiir. I' 1 ., llyj-liii f 

 Microeera from 



" f cltn " x m ' 



edge of larva 

 showing branch- 

 ing and forma- 



no., of one- and made up of a compact mass of lunate 



two-celled coni- , __. ,_., 



dia. x 1000. spores (Fig. 17). These are 3- to 



5-septate, and -jS to i<> microns long, by :>.."> to 5 

 microns thick, in fresh specimens. When the larvae 

 are placed in distilled water on a microscope slide, 

 the fungus spores are seen to float apart and spread ^om 



out in the water. 



CULTURES. 



Culture- if this Microcera were grown much more easily and quickly 

 than those of any of the previously described fungi. This" fungus grew 

 rapidly on nearly all kinds of media which were tried. 



On September II. I'.in;, the day after the fungus had 

 been examined and recogni/ed as a new parasite on Alc\- 

 rodes citri. three- sets of petri dish cultures of three each, 

 A. U. and C, were prepared according to the usual method 

 For isolation. The first Se1 was made by touching an in- 

 fected larva with a moist platinum needle, and washing 

 the needle off in test-tube A. I', received three loops from 

 A. and T three loops f n .in I'. In three days on petri dish 

 A. two mycelia and a number of bacterial colonies were 

 evident. In nine days, the fungus had overrun almost tin- 

 entire dish, in spite- of the bacteria present, and was pro- 

 ducing an abundance of conidia. \\ and C developed no fungus. 



Fijf. IK. Cr.Ili.1iK 



I-., 111 i, .-i tube '-ul- 



on broiil. X I.Vi. 

 < Cullur.- hud <1ri-l 



