Scorpions prey on other insects and small animals. They will even eat each other if there is not enough food around. Crickets are one of their most common diets. If you are keeping a scorpion as a pet you will find pet shops that will sell "tame" crickets. Tame crickets do not jump or try to escape. Wild crickets will jump away. Wild crickets can cause problems for pet scorpions in glass aquiriums because the cricket can jump up in a corner or onto the top of the aquirium. Since scorpions can not climb on glass the wild crickets will most likely go un-eaten.
Some larger scorpions have been known to kill small animals and birds. This is uncommon for bark scorpions as they are a much smaller species. Since bark scorpions are nearly blind they do not fair well against most other scavangers and predators.