Beneficial Garden Bugs

• The Hover Fly -- The larval and adults stages of hover flies (also called flower flies) feed on aphids.
• Tachinid Flies -- These tiny creatures have larvae that are parasites of insects, particularly caterpillars.
• Earthworms -- Yes, worms can actually help your garden. They burrow extensive tunnels in the soil, and these can allow water to drain well and let air reach the roots of your plants. Worms also feed on dead plant material, so their presence in slow-acting compost piles can speed up the conversion of debris to compost.
• Centipedes -- These multi-legged insects are active at night when they prey on a variety of small soil animals and their eggs.
• Praying Mantids -- These stick-like insects eat a variety of other insects (including known pest bugs).
• Lady Bugs -- Most people are attracted to the pretty colors of lady beetles, but they're also helpful to your garden because they prey on aphids. Some also eat powdery mildew fungal spores (there's no accounting for taste, eh?) as well as spider mites, scale insects, and mealybugs.
• Flower Bugs -- These are also known as minute pirate bugs. They're small and are general predators of thrips, aphids, mites, eggs, and other small insects.

Though this isn't a complete list of all the helpful bugs out there, hopefully it's got you thinking that not every insect that wanders into your garden is your enemy. For more information, grab a book like American Horticultural Society Pests and Diseases: The Complete Guide to Preventing, Identifying and Treating Plant Problems.