Why we love spi­ders

Yes, they re­ally are good for our gar­dens!

Manitoba Gardener Magazine - - CONTENTS - By Heather Klein

The sci­en­tific name for the spi­der is “arach­nid”. This name has its source in a Greek myth about a princess named Arachne. Arachne was an ex­pert weaver whose fame even­tu­ally reached the ears of the god­dess Athena. Athena de­cided to chal­lenge her to a weav­ing con­test, but she un­der­es­ti­mated Arachne’s skill and lost. Over­whelmed with jeal­ousy, Athena turned her into a spi­der to spin silk for­ever.

We all know that birds are in­cred­i­bly help­ful of get­ting rid of in­sect pests, but did you know that spi­ders are highly skilled at this as well? No other crea­ture eats as many in­sect pests. And since they are es­pe­cially at­tracted to the good eat­ing avail­able in di­ver­si­fied gar­dens, these eight- legged crea­tures can be counted on to go af­ter the in­sect pop­u­la­tion when they show up in our gar­dens at home.

Spi­ders will go af­ter flies, mos­qui­toes, moths, bee­tles, wasps and other in­sects around our homes and gar­dens. How­ever, they don’t dis­crim­i­nate. They also eat ben­e­fi­cial crea­tures: la­dy­bugs, hon­ey­bees and but­ter­flies. But the harm they can do is far out­weighed by the good.

There are more than 3,000 spi­der types in North Amer­ica and an amaz­ing 38,000 species world­wide. They have spent more than 300 mil­lion years on this planet, with suc­ces­sive gen­er­a­tions be­com­ing in­creas­ingly com­plex, highly skilled and dif­fer­en­ti­ated.

One clas­si­fi­ca­tion method di­vides this vast pop­u­la­tion into two group­ings – “hunters” and “web spin­ners” – re­fer­ring to the core tech­niques the spi­ders use to catch their prey.

The “web spin­ners” – there are some 3,000 spin­ner species – are the more vis­i­ble and known for the silk nets they cre­ate to en­snare their prey. The orbs are web sheets formed into wheel-like shapes; built with an amaz­ingly sturdy thread that emerges as liq­uid silk from the spi­der’s ab­domen and, ma­noeu­vred by their cre­ators into upright po­si­tion, these webs have proved through the ages to be highly ef­fec­tive traps for fly­ing in­sects.

“Hunter” spi­ders rep­re­sent a much larger pop­u­la­tion, em­brac­ing a very large num­ber of fam­i­lies. They have

de­vel­oped a huge va­ri­ety of meth­ods for catch­ing prey. Sci­en­tists will tell you that what most hunter meth­ods have in com­mon, though, is the fact they don’t use webs. Hunter species in­clude wolf spi­ders, jump­ing spi­ders, the su­per-numer­ous, widely dis­persed night crawlers and copy­cat sac spi­ders (which tend to make their homes in veg­e­ta­tion and some build­ings) and crab spi­ders.

These spi­ders-hunters might em­ploy speed and strength as a tac­tic on their hunt, or cam­ou­flage com­bined with an el­e­ment of sur­prise. Or the spi­der might change its colour to match its back­ground, or sim­ply sit in a flower patch ex­ploit­ing its scents and other fea­tures to at­tract but­ter­flies and other in­sects. In­ge­nious ant-mim­icker spi­ders (yes, that’s their name) will turn them­selves into faith­ful copies of the in­sects, trans­form­ing their legs into an­ten­nae, the shells on their backs into sep­a­rate heads and tho­raxes – a de­cep­tion that read­ily wins them en­try to an ant’s nest.

Spi­ders’ homes – as var­ied as the species it­self – can be a lush bush; a deep or shal­low bur­row; a neat, self­crafted tun­nel; a banana leaf; leaf lit­ter; tree roots; or hu­man habi­tat. Many spi­ders hi­ber­nate in win­ter, emerg­ing in spring just in time to meet up with newly-awak­ened in­sects and some good spring meals.

Life for the spi­der isn’t all work and no play – though on the mat­ter of mat­ing there are some in­ter­est­ing twists. “The cou­pling of two preda­tory and of­ten short-sighted crea­tures can be a haz­ardous af­fair,” sci­en­tists tell us. The fe­male is usu­ally larger than the male – of­ten MUCH larger. Her can­ni­bal­is­tic ten­den­cies are aroused. And yes, the male is go­ing to have to work very hard, with some fancy foot­work, to con­vince the fe­male he’s not her prey.

Hu­mans, it should be said, have very lit­tle rea­son to fear spi­ders – though in fact many of us do. Yes, spi­ders carry some venom for self­pro­tec­tion, but usu­ally too lit­tle to do more harm than a mosquito bite. Spi­ders only bite hu­mans in self­de­fence, and we’re told there were only about 100 re­li­ably re­ported hu­man deaths from spi­der bites in the 20th cen­tury. En­joy your yard. The hunters and spin­ners are out there right now, work­ing on it.

Although many spi­ders catch their prey by spin­ning a web, there are also many like the wolf spi­der (above right) that catch it by de­cep­tion.

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