Dusts have been used to ward off insects from grain storage for centuries, including plant ash, lime, dolomite, certain types of soil, and diatomaceous earth or Kieselguhr. Of these, diatomaceous earth in particular has seen a revival as a nontoxic (when in amorphous form) residual pesticide for bed bug abatement. While diatomaceous earth performed poorly, silica gel may be effective.
Encasing mattresses is one of many good parts of a solution, but it doesn't get rid of the infestation. There are going to be other bugs away from the mattress, hiding nearby. What mattress covers are good at is entombing the sometimes large number of bed bugs that can live on a mattress. And because the covers tend to be uniform in color and don't have a lot of seams that the bugs can hide in, it's easier to see the insects.
One bed bug will usually take more than one bite. Once a bed bug inserts its mouthparts and finds a suitable blood vessel, it will begin feeding. However, finding the right blood vessel may take more than one injection into the skin. In addition, bed bugs are very sensitive to movement by the host they are feeding on. Therefore, if a sleeping person moves, a feeding bed bug will probably withdraw its mouthparts and begin its search for a blood meal on another part of the body. It’s important to remember that the number of bites a person receives is not indicative of the number of bed bugs that feed on that person.