Montpelier examiner. [volume] (Montpelier, Idaho) 1895-1937, 1908-01-31
PARASITES VS.. WHITE GRUB.
What illinois Expert Has Discovered
Concerning Work of Former.

The Illinois state entomologist, DR.
s. A. Forbes, of Urbana, has done
much in studying the parasites that
destroy the white grub, and the fol.
lowing items from his Office indicate
something of the beginning that has
been made in solving one of the vital
and urgent problems of the farmer.
The common grub wasp (Tiphia) is
much the most important insect enc
my of the white grub. 1t is slender,
jet-black insect, usually two-thirds OF
an inch long, with wings either clear
or tinged with dusky yellow.
1t enters the grouud in search of the
grubs, follows them up in their bur-
rows and lays on the back OF each
grub a single egg, which matches into
footless maggot-like larya which adj
heres to the surface of the grub, pune
lures its skin, and sucks it's blood for
time, but finally eats it up.
These maggots have been known to
| destroy, under favorable circum-
stances, the entire grub population OF
badly infested field. The method of
this insect and the main facts of its
life history have been worked out in
/ DR.. Rorbes'- insectary the past two
years by ]. ]. Davis and J. A. West,
from cocoons and infested grubs sent
in by E. o. G. Kelly from fields at FL
licott, Ill.
The wasp attacks the grub and q
violent struggle ensues until the for
mer stings her prey, temporarily
paralyzing it, and then smears viscid
fluid upon the back Of the grub not
far behind the head, and deposits her
!, egg on this sticky surface.
The operation occupies several min.
utes and has been fully observed
i number OF times Several white grubs
found in the field had these parasites
on the under side of the body between
the thoracic legs.
The egg matches in seven to ter
days and it takes the maggot about
two weeks to get it's full growth. i
doubles its size the last two days
3 when it devours the body of its host
5 The full-grown maggot is two-third
! to four-fifths of an inch in length.
t In several cases an abundance of 1T
e cocoons were found in the ground, In
e dicating an enormous destruction Q
white grubs. No doubt this wasp !
l. an important agent In checking dc
r structive uprisings of grubs.
e A little tachinir fly is another pare
). site Of the grub. The adult is larg
a blackish-gray fly with genera
r resemblance to the common larg
u blow fly Another parasite is tn
D young of large. slender-bodied, dar
u red ichneumon fly. Still another Is
y bee-fy covered with erect yellow fur
y Mr.. West discovered May-beetle
dropping to earth trying to rid then
j. selves of adult flies that were clingin
y to them and apparently thrusting egg
ot into their backs. The effect was teste
d. in breeding-cages. The beetles s
se treated lived for some days and the
began to die, dipterous maggots bein
found in the body. These flies wei
~ also seen among the May-beetles {
re the trees at night.
lg Nothing has been done to test Il
&c possibility of collecting and distribu
ing parasites, other than those of CO
tagious diseases, and the latter subje
has not been worked out to final co
illusions. So 1t is seen that the par
Be sites alone offer a large field for |
yestigation with view to the destru
ton of white grubs.