The good news is that your insect friends can take care of your insect enemies as long as they have the numbers, so it's up to you to staff your little insect army for the big battle by planting the things that attract them. Wasps eat earwigs, bad beetles, whiteflies, mites and aphids, among others. Ground beetles will take care of your slugs and caterpillars. Spiders are the cold-blooded killers of the pest world, taking care of just about anything that crosses their paths. Once you know what you need to kill, find out what plants will attract the right insect friend for the job.