Delaware gazette and state journal. (Wilmington, Del.) 1883-1902, 1900-05-24
THE GREEN PEA LOUISE.

Recent observations by the ento-
mologist of the Delaware College ,Ex-,
pertinent Station upon the destf uctive
green pea louise, as described below,
are OF such Importance as to make it
desirable to bring the facts inn
mediatoly before the pea growers. He
says: The growing of green peas for
the cannery is one of the most inn
portant industries Of southern Dela-
ware. One Of the largest rea- canning
factories in America, with capacity
OF l25, 600 cans per day is located at
Seaford, and in 1888 this and a half
dozen smaller plants located ut Bridge
and Milton, packed some la, 600 cases
over 1000 acres. YES ~
During the season of 1899 serio.,
blow was given this usually profitable
industry by the appearance Of . small
plant louise upon the peas in such
countless numbers as to cause an
almost entire loss OF the late crop and
from one-halt to two-thirds of the
usual yield of the earlier sorts. These
small insects, which closely resemble
the "green hy'' of greenhouses and
the "wheat aphis' Oh wheat, except
that they are considerably larger and
entirely of light pea green color,
commenced to appear about the time.
the early peas were in blossom. f
These small insects injure the plant
ty sucking its juices and thus more Oh
less depicting its vitality. Though
the few present at first did hardly any
damage, they soon multiplied SO,
rapidly, that the plants were entirely
coated with them. As a consequence
the vines soon died or very imperfectly
matured the peas. With the cutting
of the pea crop these insects were not
noticed further except here and there
in garden patches, where they might
be found until late in November.
The question most naturally arises at
once, Where were these lice before
they appeared on the peas in ths spring
or, in other words, where and in what
state do they pass the winter?"
We're 1t known that the pea louise
passed the winter upon given weed or
crop, means might be devised for SO
handling it as to prevent its spread to
the peas. Unfortunately, last spring
the lice were not noticed until well
along in May, and in the fall nothing
of definite nature was ascertained as
to their winter habits. This year
during the last month, however, the
Station Entomologist has been ex-
amiping various crops in the vicinity
of pea fields to ascertain whether they
might not harbor this pest, and
especially those crops which rein the
ground over winter. .F4
Only within the last week has he
found the louise to be excessively
numerous on crimson clover, and
though most abundant in the southern
portion of the State, and especially
near the pea fields SO badly infested
last season, the lice have been found,
very numerous as far north as Dover,
and not uncommon in New Castle
county. At Bridgeville the Ice are
still almost entirely confined to the
clover, upon which they occurred in
larger numbers than at any other point
which has been visited, aud hardly any
were found on peas adjoining the
clover. At Harrington the lice were
found rapidly advancing across one pea
field next to clover and quite generally
scattered in another large plot.
There seems to be but little doubt
therefore, that throughout Delaware
most of the pea lice have spent tho
winter on. the scarlet clover and having
reproduced so rapidly as to have be
come excessively abundant upon it
they are spreading to the peas Only.
ths winged forms will spread to the
peas, upon which they will deposit
young, which will each mature and
reproduce 70 to::30 yonng in from a week
tcl0 days, andthese winged lice are very
largely spread by the wind.
1t has been ascertained that the pei.
louise, with which as such we were IN
familiar previous to 1899, Is un-
doubtedly the same as a louise noticed
for five or six years past upon scarlet
clover. This was probably the same
insect which appeared in such Numbers
ON scarlet clover few years ago, in
enc or two instances. 1t then threat
ened the life of the crop, but was worry
quickly and almost entirely extermi-
mated by fungous disease. But few
diseased lice have been found this
peculiarly favorable conditions for the
development of this disease, 1T is
doubtful If many lice upon the peas
will bo killed by it.
If the scarlet clover in the i'm.
mediate Jointly of peas can be turned
under deeply at once commencing
upon the side nearest the peas--with-
out doubt most of the lice will be do
stroyed. as they could never regain the
surface, and their otherwise subsequent
spread would be prevented. Where the
clover is desired for forage or seed,
this may not seem feasible. ii may be
worthy of consideration in some cases,
however, whether it were better to
endanger the pea crop by leaving the
clio, er, or to secure forage by planting
COW Ieas and using COW pea hay. In
general the more scarlet clover that
can be turned under as soon as EOS
sible, tho less danger of injury to Eeas
by tho yea louise.
Various kinds of apparatus and
methods for the destr uction of these
lice are being tested in this State and
Maryland, and such as may prove
practicable will be put into immediate
use. 1t is doubtful whether early peas
will be seriously injured, but as soon
as the clover becomes overcrowdsd, the
first good breeze may carry cloud Of
the winged aphides to all parts of the
pea fields, where, if not checked by
the weather, disease, or parasites, they
may soon cause the failure Of the
medium and late crop.