Insect pests frequently have natural enemies that are beneficial in the landscape. These beneficial insects may be predators or parasites. One common example of a predator is the lady beetle. Both the larvae and adult lady beetle eat aphids and other soft-bodied insects. Other predators include lacewings, praying mantids, spined soldier bugs, flower flies, and spiders.
Parasites live on and often kill another organism, called the host.
There are parasitic wasps that use caterpillars, whiteflies, aphids, and soft scales as hosts. Another living organism that has been used as a biorational control is milky spore disease, a bacterium that parasitizes and kills white grubs in lawns. Bt contains a protein which is poisonous to specific insects, yet harmless to other organisms. Bt can be sprayed on plants. When the sensitive insect pest feeds on the sprayed leaves, it will ingest the poison and be killed.