20 NEBRASKAland • AUGUST-SEPTEMBER 2016
Night Lights
By Paula Hoppe, Certified Master
Naturalist
Spider hunting is probably not
something most of us think about, but
something that the kid in each of us
needs to try. It doesn't take any special
equipment: just take a flashlight or
headlamp – and perhaps a little courage
– and head out into the dark jungle of
your back yard at night.
With your flashlight positioned near
or just above your eyes, (the location
of the flashlight is important) look out
across the grass. A small, bright green
glow or "eyeshine" in the grass means
you have spotted a spider, and he is
looking right back at you.
Most spiders have eight eyes, and
their configuration can give you a
clue as to what kind of spider you are
observing, though this can be difficult to
discern in the field. Two large eyes, with
a small one on either side over a row of
four smaller eyes is a good indication
you've encountered a wolf spider.
Wolf spiders, Nebraska's largest
spiders, are just one of a number of
spider families that hunt or forage at
night. These predators have an iridescent
layer
called
the tapetum
lucidum located
just behind the retina.
This reflective layer bounces light back
onto the photoreceptors in the retina,
permitting them to see well in dim light.
This, along with sensing vibrations,
helps wolf spiders locate prey.
A tapetum lucidum is also found in
some mammals and birds, producing
that familiar glow we've all seen in car
headlights alerting us to the presence
of deer, raccoons and other nocturnal
prowlers.
While spiders' eyes glow green,
the eyes of moths and June bugs are
revealed as little sparks of red or
orange.
Spiders are beneficial neighbors, and
as you gaze around you may be amazed
to see the number of tiny predators that
are patrolling your backyard quietly
doing their job, keeping you safe from
overwhelming numbers of pesky
insects. ■
PHOTO
BY
JOEL
SARTORE
The wolf spider is Nebraska's largest spider,
and while its eyes shine black in studio photos
like this one, its eyes glow green when shined
with a flashlight at night.
layer
called
the tapetum
lucidum located
just behind the retina
