How do scientists trap
spiders in farm fields without hurting them? In Oklahoma, ARS entomologist
Matthew Greenstone, his assistant Brian Jones, at right, and other researchers
have used giant--but gentle--vacuum cleaners. Then the scientists figure out
what little critters a spider has been eating.
One way to do this might be to dissect the spider (cut it open), but they'd see
only a gooey mess! So, Greenstone, pictured below, and others created a
special chemical test. It can identify a prey's remains in a predator's gut.
You might call this a "gut reaction."
In a Georgia cotton field,
scientists using the test found that one type of spider really likes to eat the
eggs of two insects that attack the cotton plants.
Recently, they surveyed wheat and other grain crops in Colorado, looking for
spiders that kill aphids, which are major pests of these crops.
When scientists find a spider species with an appetite
for a particular pest, they can investigate whether these spiders might eat
enough pests to help a farmer. Scientists also want to find ways that farmers
can make their fields more inviting to the spiders.
Other bugs, like pesky flies, have plenty
to fear from spiders, though. Lots of them end up as spider snacks, although
spiders don't chew their food. Instead, a spider sips, sucking out an insect's
gooey insides and skipping the crunchy outer part.
Disgusting, maybe... But spiders might be miniature
heroes, like the long-jawed orbweaver, in the picture left. Scientists at the
Most spiders catch insects by spinning webs of strong, sticky silk.
How else do spiders capture their prey?
So, unless you're an insect yourself,
spiders are usually nothing at all to fear. Next time you see a spider crawling
around your garden, let it be and wish it well. It just might be standing guard
over your flowers and vegetables!