Grant County herald. [volume] (Lancaster, Wis.) 1850-1968, 1916-05-10
Evolution of
the Threaduorn1

Sheep and cattle frequently have
threadworms in the gullet These
worms are seen in the lining of the
gullet beneath the surface in a rath-
er striking wavy pattern similar to
that formed by a snake as it travels
over a smoothe surface. The worms
are slender and threadlike, but as
they measure from over an inch to al
most 6 inches in length and raise up
the surface of the lining of the gull
let to form slender wavy ridges, are
readily located when an infested gull
let is slit open and examined. So far
as known, the damage occasioned by
the presence of these parasites in
sheep and cattle is rather slight,
though it has been determined that
closely related parasite is intimately
associated with if not the casual agent
of cancer in the stomach of rats.
It has been shown by Investigations
and experiments in the Geological Di-
vision of the Bureau of Animal Indus
try that various species of dung beet
les are the source from which sheep
and cattle become infested with the
gullet worm. These dung beetles may
be found in almost any manure de-
post, except during the winter in cold
climates. The beetles usually crawl
under the manure deposit enter from
the bottom and feed on the inner pOr
tions Of the deposit as long as it re-
mains moist. When the BEETLES eat the
manure they swallow the gullet-wOrm
eggs which have passed down the
esOphagus through the stomach and
intestine and out in the manure of the
infested sheep or COW. AS soon as the
manure becomes too dry and hard to
work the dung beetles abandon it and
crawl into the ground or fly to other
and fresher deposits. In about
month the eggs which were eaten by
the beetles have Matched and develop
ed into an encysted stage in the body
of the beetle, ready to continue their
development when the infested beetle
is swallowed by COW or sheep.
Vegetation HarbOr For Insects.
The opportunity for sheep and cat
tie to swallow these beetles comes
when they fly from one manure deposit
to another. The flight usually ends
by the beetles landing on the pasture
somewhere near a manure deposit,
and as they crawl about through the
grass toward the manure, attracted
by the odor, they are commonly swal-
lowed by grazing animals. The beet
les are no doubt eaten unconsciously
as a rule, as sheep and cattle eat large
numbers of insects, since practically
every plant is the permanent home or
the temporary resting place of num-
Der of insects, it is perhaps a matter
of more or less Indifference to them
if they are conscious of the presence
of insects in a mOuthful of food. This
is especially true of cattle, since cat
tie or noted for eating foreign sub
stances, such as nails, wire, bolts, rub
bers, knives, etc. Among the various
kinds of insects picked up by sheep
and cattle during the course of day,
dung beetles are likely to be more or
less numerous, and of these some are
likely to harbor larval stages of the
gullet worm, now ready for the next
step in development. In the digestive
tract Of the COW or sheep the beetles
undergo partial digestion, releasing
the larval worms, which make their
way to the gullet and burrOw into its
lining. Here the worms become ma
ture and in time the famale deposits
eggs which pass down the gullet and