The larvae look like tiny black alligators with orange or blue spots on the back which is covered in spines. Both are useful if aphids are a problem. Lacewings larvae are another great aphid eater, and their larvae look similar to ladybugs, except they are brown in color. Dragonflies which skim about over ponds or near water, should be left alone. They eat mosquitoes and gnats.
Ground beetles are good insects and feed at night on cutworms, slugs and other soil insects.
Parasitic wasps are also beneficial and include braconid wasps which attack aphids, caterpillars and the larvae of many beetles. Ichneumonid wasps can help to control whiteflies, aphids and some caterpillars. Praying mantis have been seen as a beneficial insect, but don t run out and buy hundreds of them. They do eat insects, but they aren t picky. They ll eat anything in their path, including each other.