ASCHERSONIA AIvEYRODIS. 11 



Previous to Webber's publication, 21 the entomogenous nature of the 

 genus Aschersonia was not known, although up to that time__there were 19 

 species of this genus described, as recorded in Saccardo's "Sylloge Fun- 

 gorum". This species was therefore the first known parasite of Aleyrodes 

 citri, and was probably the first fungus that had been reported on any 

 species of Aleyrodes. In the course of his investigations on the sooty mold, 

 Webber reported that he had found three other species of Aschersonia, 

 parasitic on other insects in Florida ; one of which was Aschersonia tur- 

 binata on the Wax Scale (Ceroplastes floridensis Comst.). The others 

 were not determined by him. In 1897, when he wrote his bulletin on sooty 

 mold, Webber reported that Aschersonia aleyrodis was found in Florida 

 at Crescent City, Bartow, Panasoffkee and Gainesville. He also stated that 

 no sign of the fungus was apparent in groves infested with Aleyrodes citri 

 at Ocala, Orlando, Evinston and Ormond. In the same bulletin, the de- 

 velopment of the fungus, the probable method of spore dissemination, and 

 the methods of introducing the fungus on the orange trees, are discussed 

 at some length. The description of the development of the fungus in the 

 next paragraph is taken with slight changes from this bulletin. 22 



The first indication of the effect of the fungus on the larva of the whitefly is 

 the appearance of slightly opaque, yellowish spots unusually near the edge of the 

 larva. In the early stages of infection the larva becomes noticeably swollen, and appears 

 to secrete a greater abundance of honeydew than normally. As the fungus develops, 

 the interior organs of the larva appear to contract away from the margin, leaving a 

 narrow circle, which becomes rilled with hyphae. Shortly after this the hyphae burst 

 out around the edge, forming a dense marginal fringe. This may form all around 

 the larva at about the same time, or develop at one portion of the margin sooner than 

 the others. Death usually ensues, it is believed, before the hyphae burst out. Tne 

 fungus does not spread over the leaf to any extent, but grows upward in a mass, 

 gradually spreading over the larval scale. It is not uncommon to find the pycnidia, with 

 their bright coral-red masses of sporules, formed in a circle around the edge of the 

 larva while it is yet visible. As the Aschersonia develops, the hyphae spread over 

 the larva forming a dense compact stroma, which ultimately entirely envelops the 

 larva. The stroma in this stage is thin and disk-like, the fructification being usually 

 borne in a circle near the edge. The hyphae, which make up the main mass of the 

 stroma are from 8.5 to 7.5 micro-millimeters in diameter. Within the body of the 

 insect and near the pycnidia they are somewhat smaller. 



METHODS OF INTRODUCTION. 



Two methods of introducing the fungus into groves infested with 

 Aleyrodes citri were used by Webber with fair success. (1) Pinning 

 fungus-bearing leaves into trees infested with Ale\rodes citri, in such a 

 way as to cause the fungus spores to come in contact with larvae not yet 

 infected. (2) Planting small trees with fungus infected larvae in a grove, 

 so that the fungus-bearing leaves came in contact with the leaves on which 



21 Webber, H. J. Div. of Veg. Phys. & Path.. Bui. 13, p. 20, Washington, D. C., 1897. 

 "Webber, H. J. Div. of Veg. Phys. & Path., Bui. i;$, pp. 23-24, Washington, D. C, 

 1 S<)7 



