[aussow] PARASITISM OF ISARIA FARINOSA 99 
it still retained satisfactorily moisture subsequently introduced. 
I then placed a number of living adults and cocoons in this apparatus 
and dusted the whole with spores that had been produced in a pure 
culture of Isaria. The living adults had all died after three days and 
none of those (11) emerging from the cocoons contracted the fungous 
disease. After 21 days no more adults emerged, although 13 cocoons 
remained, which I had evidence to believe contained living adults. Of 
these, nine eventually developed the typical Jsaria and the moss also 
began to be covered with numerous /saria colonies. This experiment 
confirms my other observations and also indicates that the disease may 
be artificially introduced even at so late a stage in the development of 
the larch sawfly. Infection takes place in nature, no doubt, much 
earlier. 
Although none of my experiments were made under strictly natural 
conditions; that is to say in the open air, yet the observation that the 
fungus Jsaria is regularly found year after year under larch trees, when 
once it has been found, may indicate that the results obtained really 
closely show what takes place in nature. 
In conclusion, I may say that in Isaria farinosa we possess one 
certain factor, by which the increase of the larch sawfly may be con- 
trolled. Whether it is necessary to resort to these means in the face 
of the every year increasing number of insect parasitized larch sawfly 
cocoons—is somewhat doubtful. 
