You could get some diatomaceous earth. It is a fine powdery substance made up of ground diatoms. Microscopically this powder looks like glass, or razors. When any insect with an exoskeleton or waxed coating walks on or through it, it makes scratches on the insect and the damage results in the dehydration and ultimate demise of the insect. It works on earwigs, ants, fleas, beetles, arachnids...most insects, in fact. You can buy it at any home hardware and it is very cheap, safe around children and pets, completely non toxic and environmentally safe.
I have used it with great success. My girlfriend spread some in cracks along her pool area, and they did not see an earwig for six weeks; their infestation was fairly severe too.