In such cases the weeps consist of small-diameter plastic, clay or metal pipes extending through the wall to a layer of porous backfill. Typically, weeps are arranged to direct water which may have entered an assembly from outside back to the outside.
A few of several safe household chemicals to use are vinegar, dishwashing soap and rubbing alcohol, according to an Oregon State University Extension Service publication called Using Home Remedies to Control Garden Pests, (EC 1586). The publication, complete with photos, is available free of charge online.
Sprinkle DE along outside edges on window sills and doors to prevent spiders and ants from entering the house.  Pour into a lawn spreader and apply diatomaceous earth to yard to kill fleas, tics, chiggers and other biting insects that attach themselves to pets. Sprinkle on bushes with a strainer.  Apply diatomaceous earth on garden soil and plants to protect them from vegetable-loving insects.