4
THE ESSEX NATURALIST.
which merely seemed to become segmented and to increase in
size. Its head was inserted through the skin of the beetle larva,
which shrank as the Methoca larva increased by the absorption of
its host. When four days old it shifted its position and took a
fresh hold. No moults were apparent. Finally, one evening the
Methoca larva disengaged itself, and I found it apparently trying
to escape from the top of the burrow. I gently persuaded it to
return to the bottom, and it commenced to spin some threads
round the earthen wall. However, it knew better than I which
was the right place to spin up, and next morning I found the
cocoon being formed at the top of the open burrow.
Photographs were taken daily ; some showing the progress
of developments appear on Plate I. The female was captured
on August 26th, and I received it on the same evening. The
Tiger-beetle larvae were obtained and established next day, and
Methoca was introduced, and she laid the first egg on the following
day and the second on the day after that. The latter hatched in
seven days and the cocoon was completed twelve days later.
The larva from the first egg became displaced from the host
when about half grown, and I noticed it resting on the glass wall
of the burrow. It was replaced and soon resumed feeding.
Profiting by the experience obtained from the other larva, I closed
in the top of the shaft, so that when the second had finished
feeding it had no difficulty in starting to spin under slightly more
natural conditions. This it commenced to do twenty-four days
after the egg was laid, and the cocoon was completed about two
days later.
I have no information as to the time that elapses before
pupation, but by analogy with other hymenoptera I have
studied, I conjecture that the pupa is formed late in the spring
of the following year. The imagines will probably appear next
July or August.
With reference to the statements that the male is rare, Mr.
H. T. Pagden, of Christ's College, Cambridge, carried out some
experiments with Methoca, commencing in 1924, and the results
were communicated in a paper to the Entomological Society in
December, 1925. He observed the stinging of the Beetle larva
much as described by the other observers and subsequently
bred out a single female. He then introduced her to several
Cicindelid larvae in their burrows and later on obtained five