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.
Commercial pesticides have been widely used for years in the garden, most of which are made from chemicals that are harmful to ground water and the soil. Organic gardening is becoming more popular with the use of organic materials such as manure for fertilizer and household products as weed killers. Essential oils have a place in the garden as well. Various essential oils are used as a pesticide and are very effective. Make your own pesticide with different essential oils.