50 OUR SHADE TREES AND THEIR INSECT DEFOLIATORS. 
vigor enough to transform into pup; later the fungus grew, and, press. 
ing the chitinous portion of the pupa apart, forced its way to the air 
to fructify. 
‘Plants not usually edten by the caterpillars, as well as others not 
eaten at all, have upon them the largest numbers of caterpillars killed 
by the fungus, provided that they grow in the vicinity of suitable 
food-plants. Perhaps unsuitable food, predisposing the caterpillars for 
any disease, is one of the causes of the innumerable host killed by this 
fungus. 
“The white cocoons of a parasite (Apanteles hyphantrie Riley) of 
this caterpillar were in some cases observed to be covered with similar 
spores of a fungus. Opening such cocoons it was seen that the spores 
were not simply blown upon the silk and there retained, but that 
they came from the victim within, and had forced their way through 
the very dense silken covering.” 
Experiments to obtain percentage of diseased caterpillars. 
Experiment I: 
One hundred and twenty-five nearly grown caterpillars were gath- 
ered (October 7, 1886) at random in one of our public parks. 
They were imprisoned in large glass jars and daily supplied 
with suitable food. 
Result, October 18, 1886: 
11 apparently healthy pupe. 
3 deformed pupe. 
18 yellow cocoons of Meteorus hyphantrie. 
9 dead pupex, killed by fungus or otherwise. 
84 dead caterpillars, killed by fungus or otherwise. 
125 
In the earth of the jar were found 17 pup of Tachina flies, leaving 
67 caterpillars and 9 pupe killed by the fungus, or 61 per cent. 
_Lxperiment IT: 
One hundred and twenty-five nearly grown caterpillars were gath- 
ered (October 7, 1886) from a trunk of a Soft Maple tree (un- 
suitable food) and treated as above. 
Result, October 18, 1886: 
8 apparently healthy pupe. 
1 deformed pupa. 
7 yellow cocoons of Meteorus hyphantric. 
3 dead pupe, killed by fungus or otherwise. 
104 dead caterpillars, killed by fungus or otherwise. 
2 cocoons containing Tachina larve. 
125 
