The herald-advance. (Milbank, S.D.) 1890-1922, 1909-10-08
Electric Search Beams Lure
Moths Into Ceath Traps.
Measure Made Necessary by Ravages
OF insects Known as "Nuns,"
Which Threatened to Destroy
Conifers of Saxon Forests.

Berlin.-The foresters of Germany
lure noxious insects to their doom by
the use of electric lights and other
fiery attractions.
The experiments OF the %foresters
were made necessary by the ravages
OF moths, known popularity through
out Germany as the nuns which
threatened to destroy the conifers of
the forests of Saxony.
The moths in question are most &C
tive between the hours of 10 p. m and
l a. m, and they are then attracted
powerfully toward sources of light.
Experiments demonstrated that the
nuns" were attracted by the flame of
burning wood; more strongly by ace
tylene Of magnesium lamps, and most
powerfully by the electric arc.
The alluring of the moths was &C
complished at Zittau by cooperation
between the foresters and the munich.
pal electric works. The entire stock
OF arc lamps was linked together, aft
er the globes had been removed. and
set in activity after nightfall.
Although the forests were several
miles distant the effect of the total
illumination was sufficiently strong to
attract vast swarms OF moths from
their leafy shelter.
They futtered about the glowing
carbons and quantities fell to the
earth with singed wings. Although
great numbers were permanently dis
abled, it was evident that the destruc-
tive factor must be greatly multiplied
to attain appreciate results.
For that reason another plan was
tried. AT IL p. IN. the street lights
were turned off. Electric searchlights
with a current Of 40 amperes were
mounted and their powerful rays were
directed upon the ~neighboring forests
These searchlights exerted great at
tractive force, which was increased
by linking to each two arc lamps with
globes. Between these two lamps a
powerful suction ventilatOr was sta
toned. A piece of wire netting was
placed opposite the outlet OF the ven
tilator a few inches distant.
The results were startling. The
moths came from the forests in enor-
nous numbers and sooner or later
were sucked into the ventilator and
hurled by it against the wire netting
with such force that the wings were
broken and the insects rendered help
less or killed outright.
Four of these devices were installed
in the town of Zittau on the roofs of
buildings. A few minutes after the
%searchlight is turned on scattered
moths appear. Then the Aumber rap
idly increases until thousands arrive
simultaneously and flutter in and out
OF the great beam Of light.
Steadily they near its source until
suddenly they are within the grasp Of
the unseen suction of the v%entilator;
and in q second they pass through it
and fall crushed and helpless to the
bottom of the wire cage. The maxi
mum result attained In q single night
by this method was a total weight IT
III pounds, representing about 400.
900 dead moths.
, The outcome of these experiments
has been 30 convincing that it will b.
continued IN q much more extended
scale. The officials OF the United
States department of agriculture have
been greatly interested by the reports,
az the question OF protection from in
sects enemies of shade trees In New
England and OF. American forests
generally has OF late assumed much
prominence.
Experiments in America, 1t 10 report
~. along The tines laid down By the