Caterpillars on the grass, part two

A few of the dead caterpillars had small amounts of fungus growing on them.  Was the fungus the killer or simply an opportunist benefiting from the work of another?

A dead caterpillar with some light gray fungus visible between it and the grass.

There seemed to be no way to tell.  However, when I returned to the meadow to investigate again a couple of days later, I made an exciting discovery -- in addition to several more dead caterpillars, there were two that weren't dead yet.

The first sick caterpillar, wet from a recent rain shower.

Although they appeared much less dead than the others, these caterpillars were still far from healthy.  When I clipped their grass stems and collected them for observation, the caterpillars did not react and just remained tightly attached to the grass.

Another sick caterpillar clinging onto grass.

There were no signs of external damage, making it unlikely that the caterpillars had been attacked by a predator.  Instead, whatever was ailing them was probably still inside them.

To be continued...