There are many varieties of spiders, though not all are venomous. Spiders usually only bite when provoked, but care should be exercised in all contact with these creatures. Unpopular as they are, few spiders are actually harmful to humans, generally with fangs too weak or small to puncture our skin. The majority are guilty only of annoying us with their habit of building webs across doorways etc and scaring us when we least expect it ! However, destruction of any insect or spider should be avoided unless they are directly detrimental in some way. Spiders can often be beneficial by feeding on insects like flies and crickets, carrying out their role in balancing the ecosystem.