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.
Insect Pests. Rodale's Ultimate Encyclopedia of Organic Gardening recommends either red pepper spray or ground red pepper as a broad-spectrum, organic treatment for a number of insect pests. Among those insects that may be repelled by red pepper are aphids, lace bugs, cabbage maggots and spider mites.