NATURAL CONTROL OF CITRUS MEALYBUG IX FLORIDA, 9 
noted, this stage has been found much less abundantly in Florida 
than the conidial stage. This is perhaps due to the fact that the 
insects in which it occurs are invariably small in size, and usually 
hidden in bark crevices or other situations where their detection is 
difficult. The method of formation appears to be zygosporic, but a 
sexual jjroeess has never been actually observed. Specimens have 
occasionally been observed such as that drawn in Plate I, IS, but 
the exact nature of the association of the hyphal bodies to the resting 
-pores has not been determined. The mature resting spore, how- 
ever, is invariably provided with a hyaline papilla or protuberance 
which indicates that a sexual process somewhat like that described 
by Thaxter in E. fresenii, to which E. fumosa is in many other re- 
spects similar, has taken place. It is, in fact, difficult to explain the 
presence of this protuberance in any other way, for no known type 
of azygosporic formation produces such an appendage. 
The nature of the factors which in the one instance cause the 
hyphal bodies to form conidia and in the other instance to form 
resting spores is incompletely understood. In certain species of En- 
tomophthora both types are formed simultaneously in and on the 
same individual, but in E. fumosa they are not associated, diseased 
insects showing either conidia exclusively or resting spores exclu- 
sively. In E . pseudococci the writer 9 showed that zygospore forma- 
tion could be readily induced by placing cultures containing c; ma- 
tured " hyphal bodies in darkness, and it seems probable that the 
same factor plays a part in the present instance, because, while the 
fungus was collected at various hours of the day, only mature 
resting spores Avere observed. Xone were seen in the process of 
formation during daylight hours. In certain other similar fungi, 
such as Massospora cicadina, the seasonal factor seems also to play 
a rather definite role. Resting spores of this form are produced 
late in the season only, after the conidial formation has ceased. In 
E. fumosa resting spores were in fact first observed at the time the 
mealybugs were becoming noticeably less numerous, though the 
small size and inconspicuousness-of such infected insects may likewise 
have been factors preventing an earlier discovery. 
As in many other species of the genus, the resting spores have 
never been observed to germinate. Failure to secure germination 
is apparently due to the fact that suitable artificial environmental 
conditions have never been supplied. In certain species, such as 
E. pseudococci, however, a germ tube arises from the resting spore 
which produces a coniclium that is discharged in the usual manner; 
from analogy, therefore, it is believed that a similar process occurs 
in the species that have not yet been cultivated artificially. 
: ' Speare, A. T. Op. cit. 
