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.
Natural Products for Managing Landscape and Garden Pests in Florida. Ideally, insecticides and fungicides should reduce insect and disease problems; be target-specific (kill the pest, but not other organisms); break down quickly; have low mammalian toxicity; and have minimal impact on the environment.