The silver messenger. (Challis, Idaho) 1890-1912, 1908-03-10
PARAs,TEs vs. wHIrg eRua.
What Illinois Expert Has Discovered
Concerning Work Of Former.

The Illinois state entomologist, DR..
8. 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 a slender.
jet-black insect. usually two-thirds Of
an inch long. with wings either clear
or tinged with dusky yellow.
1t enters the ground In search Of the
grubs, follows them up in their bur-
rows and lays on the back of each
grub single egg, which matches into
a footless maggot-like larva which ad-
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 ]. J. Davis and J. A. West,
from cocooRs and infested grubs sent
in by E. o. C. Kelly from fields at FL
licott, Ill
The wasp attacks the grub. and a
violent struggle ensues until the for
mer stings her prey. temporarily
+ paralyzing it, ard then smears a 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 a
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 ten
days and it takes the maggot about
two weeks to get its full growth. It
doubles its size the last two days.
when it devours the body of it's host.
The full-grown maggot is two-thirds
to four-fifths of an inch in length.
In several cases an abundance of its
cocoons were found in the ground, in.
dicating an enormous destruction OF
white grubs. No doubt this wasp is
an important agent in checking de
structive uprisings Of grubs.
a little tachinir fly is another para
site Of the grub. The adult is a large
blackish-grsy fly with a genera
resemblance to the common largs
blow fly. Another parasite is the
: young of a large, slender-bodied, darl
red ichneumon fly. Still another is (
bee-fy covered with erect yellow fur.
Mr.. West discovered May-beetIe,
dropping to earth trying to rid them
: selves of adult flies that were clinginl
to them and apparently thrusting egg
[ into their backs. The effect was teste'
+ in breeding-cages. The beetles s.
e treated lived for some days and the
began TO die, dipterous maggots bein
found in the body. These flies wer
= also seen among the May-beetles o.
e the trees at night.
g Nothing has been done to test tn
e possibility of collecting and distribu
ing parasites, other than those of col
tagious diseases, and the latter subjeC
has not been worked out TO final cor
illusions. So IL is seen that the par;
e sites alone offer large field for il
vestigation with view to the destru
ton of white grubs.