The increasing use of home pesticides is creating a biodiversity imbalance, biologists say.

As more people treat their homes with pest control, the spiders and cobwebs may disappear but other insects and pests will thrive.

''If we go out there and kill all the spiders, which are natural predators, then the number of cockroaches and mosquitoes are just going to increase,'' said University of Sydney biologist and PhD student Elizabeth Lowe.

''By removing the spiders from these systems, you're exacerbating the problem of having some of these herbivorous insects that are becoming pests as well.''