10 BULLETIN 1117, U. S, DEPAETMENT OF AGKICULTUKE. 



SYMPTOMS OF THE DISEASE CAUSED BY E. FUMOSA. 



The body of a healthy mealybug is more or less pliable, and, when 

 depressed with the point of a penknife, will return to its original 

 position when the pressure is withdrawn, much like a rubber ball. 

 Mealybugs infected with this fungus in early stages of the disease to 

 all outward appearance seem quite healthy, and in fact move about, 

 though in a relatively sluggish manner. If, however, they are pressed 

 with a penknife, the body wall ruptures very easily, permitting a 

 droplet of milky white liquid to exude. When the body of a recently 

 dead mealybug, which is also lifelike in appearance, is treated in this 

 manner the depressed area remains sunken. Mealybugs were con- 

 sidered dead when upon being prodded with a needle no body or leg 

 movement resulted. ^'\n;ien the insect has been dead from 12 to 18 

 hoursi its body, although remaining lifelike, will appear more or less 

 solid to the touch, and if considerable pressure is applied to the pen- 

 knife it will cut like a piece of cheese. These are in brief the first 

 symptoms of the disease observed by the writer which can be de- 

 tected with 'a hand lens or naked eye. In 24 hours or so after the 

 first of such symptoms have been observed, a change in external 

 appearance takes place. Infected insects at this period and later 

 may present dissimilar charactei'istics, and by the uninitiated the 

 cause of death would probably be erroneously attributed to different 

 organisms. In the one instance the infected insects appear to be 

 enveloped in a dark slate-gray woolly covering. Such an appear- 

 ance indicates that the conidia, the thin-walled reproductive bodies, 

 formed externally and abundantly when conditions are favorable 

 for their dissemination, are being produced. In the other instance 

 the infected insects appear jet black in color, sometimes almost 

 glistening, and the body surfaces are smooth, not woolly. The jet- 

 black color is due to the enormous numbers of spherical black rest- 

 ing spores formed internally, the color of which is transmitted 

 through the thin, intact, translucent body wall. Those presenting the 

 first noted characteristics are by far the most abundant, whereas those 

 in which resting spores are formed are rare, detected with difficulty, 

 and occur invariably in young or at least very small individuals. In 

 both instances the infected insects are attached rather lightl}^ to the 

 host by the insertion of their proboscides. 



THE FUNGUS IN THE GROVE. 



As noted, the fungus has been found in several isolated regions 

 within the citrus belt and is assumed to have a general distribution. 

 Most of the observations herein recorded ^vere made either in Or- 

 lando or Winter Park in 1920, or in Orlando and Winter Haven 

 in 1921. In Winter Haven one definite grove was visited at about 

 weekly periods throughout the season. 



