Re: RE:Spiders

From: Bill Shear <BILLS@hsc.edu>

What a wise posting from James Brooks.  The importance of spiders in pest
control has been demonstrated by research at the University of Tennessee,
where it was found that simply providing improved habitat for spiders
resulted in a drastic reduction in pest insects on broccoli and other
vegetable garden crops. This research was a landmark because it showed that
general predators, as opposed to specific ones that attack only a single
pest species, can be effective in biocontrol.  Previously the use of
specific control species was dogma.

Let me also say a word in favor of harvestmen or daddy-long-legs.  They
feed almost entirely on small, immobile insects like aphids and mealy bugs.
I've found they can effectively keep populations of these pests low, just
as ladybird beetles do.  Harvestmen are less effective because they are not
so abundant as the beetles, but they do have an impact.  With everything
working together, control can result.

James made a good point.  We have created a lot of our "pest" problems
outselves by the indiscriminate use of poisons which have their greatest
effect on predatory species.  I hope we will begin to look more at a
"natural" style of gardening, be willing to accept some minimal damage to
plants as the cost of improving the environment for everyone, and keep the
poisons on the shelf for real emergencies.


Bill Shear
Department of Biology
Hampden-Sydney College
Hampden-Sydney VA 23943
(804)223-6172
FAX (804)223-6374
email<bills@hsc.edu>

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