BlO—Lancaster Farming, Saturday, January 14,1984
WASHINGTON - At night the
woods are full of glowing eyes,
sticky webs, spiders hanging in
midair, walking sticks, owl flies,
moths, and other flying things.
That’s the way biologist Mark K.
Stowe likes it.
Just after dusk he slips into the
stillness of the Devil’s Millhopper,
a thickly forested state park in
northern Florida, near
Gainesville. Equipped with a
headlamp, he usually stays until
dawn looking for certain kinds of
spiders that come out only at night
and lurk ont he underside of
leaves.
At first glance they look like
other members of their ancestral
family, the orb weavers. But
they’re different. They gave up
spinning the traditional web a long
time ago.
Mimicking Moths
Instead, these spiders get all the
food they need by luring male
moths. Somehow during the course
of evolution they developed the
remarkable ability to mimic the
sex attractant odors of female
moths. They capture and live on
male moths exclusively.
“Sometimes I’ve watched as
many as four moths at a time
struggle against the wind, ap
parently to compete with each
other to get to the female,” Stowe
says. Instead, they meet a deadly
fate: one of two genera of spiders,
Kaira, “the snatchers,” and
Mastophora, “the bola hurlers.”
To catch their prey, Kaira
spiders hang upside down from a
silk trapeze line with their legs
outstretched and snatch moths out
of the air.
The Mastophora spiders use a
front leg to fling a short line of silk
with a droplet of glue on the end.
The glue instantly sticks to the
wings of an approaching moth, and
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the tethered prey is hauled in,
wrapped in silk, and eaten.
“I’ve never seen a moth break
away from a successful spider
strike,” says Stowe. “That glue
has physical properties that man
would be hard pressed to repor
duce. Also, the bola line can
stretch out up to six times its
original length and absorb some of
the energy of the moth’s struggle. ’ ’
It is unusual for spiders to at
tract their prey, and even rarer for
them to exploit the sexual signals
of another insect to do it, says
Stowe.
“Unlike the typical orb weavers,
which catch anything that happens
to fly into their webs, these spiders
don’t wait for insects to arrive by
chance. Not that they’re fussy, but
all the are able to catch is moths.”
Their better mousetrap is geared
to the moths’ nocturnal activities
and can net them up to eight moths
a night, depending on size. Some
spiders can snare moths that are
twice their own body length
FARM SHOW Pennsylvania 4-
H’ers won awards for some
unusual exhibits at this year’s
Farm Show. Nestled in a comer of
vhe Farm Show building were the
entomology exhibits. Here are the
results:
ORANGE
GREEN
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LT. BU/E
LT GREEN
6.
7.
8.
9.
10.
Hunt by Night
4-H'ers Win
Entomology Awards
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Both the trapeze and the bola
represent evolutionarily reduced
orb webs. The spiders, which are
found only in North and South
America, must periodically re-spin
these webs throughout the night.
Stowe, who won first prize in an
eighth-grade science fair with a
project on spiders, is now com
pleting his doctoral work on Kaira
and Mastophora spiders at Har
vard University. His field research
is partially supported by the
National Geographic Society.
To witness all this activity,
Stowe must turn off his headlamp
and use special infrared viewing
equipment. Moths do not display
normal sex attraction behavior in
even the dimmest of visible light.
Vibrations fromt he approaching
moths prompt the spiders to flick
the bola or grab out with thier legs.
To make things harder for the
spiders, the same response can
also be elicited by such diverse
stimuli as human humming and a
jet plane passing overhead.
mwiuu Members
1 Edward Royer Lebanon 2 Tammy Messier
Furnace 3 Brian McClue Covington
Second Year 4-H Club Members
1 Becky Tice Mamsburg 2 Linda Beatty
Home, 3 Pam Ross Marion Cr
Third year 4-H Club Members
1 Michael Dwyer State College 2 David
Beatty Home Emily Ross Marion Ctr
Fourth and Fifth Year 4-H Club Members
1 Sylvia Royer Lebanon 2 Brian Petro Fur
nace 3 Lewis Beaty Home
Did You Know?
Dinosaurs have come and
gone, but the horseshoe crab is still
around, and its looks have hardly
changed over the past 300 million
years. Only a few other creatures,
most notably the cockroach, look
so much like their ancient an
cestors.
Some pet tortoises are said to
have excellent vision and strong
loyalties, says International
Wildlife magazine. Tortoises can
recognize their owners from a
distance, while ignoring strangers.
Bats have been extremely
valuable in scientific research that
aids mankind. Research on bats
has contributed to development of
navigational aids for the blind, new
vaccines, artificial insemination
and birth-control methods, and to
studies of aging and space biology.
The saying, “rain is good for
fishing,” is true. Insects may be
knocked into a lake or stream by
wind or raindrops, which brings
insect-eating fish, such as
bluegills, to the surface, where it’s
easier for people to catch them.
Raindrops also break up the
smooth surface of the water,
making it harder for fish to see
people fishing.
Only the sturdy caprenter bee
can lift the flap of the Brazil nut’<s
First calf is bom
Farm Show A spanking new
Jersey heifer calf was delivered
Sunday at 10:30 p.m. to Mar De
Prince Minnie, a three-year old
cow owned by Mar De Farm,
Newburg. The sire is “Belles
Merry Rudolph.”
The first arrival at the 1984
Farm Show is owned by Mark
Deaven. The Deaven Family milks
a herd of 40 Jersey cows.
.n
flower to get at the pollen, says
International Wildlife magazine.
Without the bee, the plant could not
reproduce, and Brazil would lose
an important economic crop.
In the fall, even the tamest
buck deer can turn mean enough to
charge humans with their har
dened, pointy antlers, especially if
the buck hasn’t found a doe to
mate.
The African lungfish can live
out of the water for months at a
time because, in addition to gills, it
has an air bladder, an organ that
works much the way lungs do.
Each person in the United
States uses about 90 gallons of
water a day for cleaning and
gardening; two more are used for
drinking and cooking, National
Geographic World reports.
Hawaii’s island of Kauai is the
last home of the nearly extinct ’o’o,
a forest bird whose yellow feathers
once were used to make the cloaks
of the Hawaiian chiefs.
People have been going up in
balloons for 200 years, National
Geographic World says. In 1783,
the first balloonist drifted 5M> miles
over Paris during a 25-minute ride,
a flight that was witnessed by a
well-known American diplomat,
Benjamin Franklin.
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