34 FUNGI PARASITIC UPON ALEYRODES CITRI. 



cushion-shaped masses, 5-septate, 4060 microns long; most of them 40 

 microns, few 60 microns. On June 2, 1908, from culture on bread made 

 September 25, 1906, dried out; conidia 1530X34.5 microns. 



DISTRIBUTION OF MICROCERA SP. IN FLORIDA. 



Sutherland September 13, 1907. 



Manatee September 18, 1907. 



Gainesville September 21, 1907. (Introduced.) 



Leesburg October 11, 1907. 



Orlando November 25, 1907. 



Largo November 1907. 



Titusville December 3, 1907. 



Safety Harbor March, 1908. 



VII. THE BROWN FUNGUS OF ALEYRODES CITRI. 



In March, 1896, H. J. Webber 56 discovered this fungus on whitefly 

 larvae in the grove of J. H. Viser, Manatee, Florida. During the summer 

 of that year the fungus spread rapidly through the Viser grove, and was 

 observed to be a very effective parasite of Aleyrodes citri. As no fructifica- 

 tion of any kind has been found in connection with this fungus, it has not 

 been classified. It has been known since its discovery as the "Brown 

 Fungus" of the whitefly (Plate VII, Fig. 42). 



INSCRIPTION. 



Webber 57 gave a general description of this fungus in Bulletin 13 of 

 the Division of Vegetable Physiology and Pathology, as follows : 



The mature stroma is compressed hemispherical, frequently having a slight de- 

 pression in the apex over the center of the insect, where the hyphae come together as 

 they spread from the edges of the scale in their development. The size varies greatly, 

 according to the stage of development of the insect attacked. In very young larvae 

 it is from l / 4 to l /2 a millimeter in diameter. In mature larvae and pupae it frequently 

 reaches 2 millimeters in diameter. The thickness, or height, also varies in like manner, 

 specimens on mature larvae or pupae being usually from 175 to 260 microns, while 

 those on young larvae are much thinner. * * * The stroma is commonly seal 

 brown, with a shade of chestnut, but becomes slightly darker with age. * * * The 

 hyphae, which make up the body of the stroma, are light brown, very tortuous, and 

 but slightly branched. Those in the body of the insect are of similar character, but a 

 much darker brown. From the base of the stroma a ground mycelium, or hypothallus, 

 spreads out in all directions on the surface of the leaf, forming a compact membrane 

 near the stroma, but becoming gradually dispersed into separate filaments. * * * 

 The hyphae of the hypothallus are colorless, sparingly branched, mostly continuous, 

 having only an occasional septum, and are from 5 to 7 microns in diameter. In some 

 places in the hypothallus. where the hyphae are apparently somewhat massed and 

 knotted, tlu-y become light brown, similar in color to the isolated hyphae of the 

 stroma. 



Div. of Veg. Phys. & Path., Washington, 1). C.. I',ul \\\ p. "7 is7 

 Ibid. pp. 28-30. 



