Abstract
(1) The oesophagi of five deer were stripped and
inspected but no larvae were present.
(2) Forty -seven carcases were split and the spinal
canals examined, but there was no sign of larvae,
nor any trace left by the larvae in the epidural
space.
(3) i igrating first instar larvae were encountered only
under the skin and between the muscles, and by
plotting their respective positions on various
carcases throughout the season, their route could
be established. it was suggested that the eggs were
laid on the lower parts of the legs, the forelegs
being chosen in preference to the hind legs. After
the larvae hatch out and burrow into the skin, they
remain in these lower parts for some time before
moving towards the back. From the forelegs, their
route takes them up over the shoulders towards the
spine and then in a posterior direction to assume
their position along the flanks. Those on the
back legs move over the thighs and then anteriorly
to the flanks. This migration requires almost
six ilonths, at the end of which time the larva moults
to the second instar.
(4) The second and third instars are non -migratory and
develop in the one position under the skin. The
second/
- 54 - second instar larvae moults after about six weeks,
the third instar larvae being found from the end of
January onwards.
() The third instar larvae may mature in one month.
As they develop they change in colour from white,
through yellow and brown to black, and the
integument becomes leathery and waterproof to
withstand the variable conditions without the host.
(6) The larvae emerge and pupate on the ground in two
to nine days.
(7) Flies emerged in the laboratory in three to four
weeks. They are actively ovipositing during May
and June.
(8) The behaviour of adults in captivity is described.
They do not feed and their life span is restricted.
(9) The sex of the host and its acquired resistance
governed by its general condition, affect the
development of the larvae. The grubs may be
parasitised by a fungus. Climatic conditions and
their effect on the various stages are discussed.
(10) Deer movement is shown to have an effect on the
resulting infestation of warble larvae.
