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.
To control damage to plants, use kaolin clay mixed with water. In a garden sprayer, combine 3 cups of powdered kaolin clay in a gallon of water and mix throughly. Spray the mixture onto any affected plants, and then flush the sprayer out to remove any clay residue.