Beneficial Insects

— Written By Susan Condlin and last updated by

Insects in the garden can be devastating. You’ve spent all your time planting, watering, and maintaining your garden. You want to enjoy the fruits of your labor – not feed pesky insects. No need to fear, Mother Nature has supplied natural predators that feed on your insect nuisances!

When we think of beneficial insects, the ladybug (or more correctly, the lady beetle) comes to mind. All developmental stages of the lady beetle (except the egg, of course) feed on soft-bodied insects, such as spider mites and aphids. The larvae (young lady beetles) look similar to tiny bluish-black alligators with orange spots. They can eat over 400 aphids during their development to an adult. There are a number of different species of lady beetles present in North Carolina; adults can range in color from reddish-orange to yellow to pink. Some have black spots, some don’t. The coloration serves as a warning to predators that they taste bad! Adults will eat over 5,000 aphids during their lifetime.

Lady beetles are not the only good guys out there. Others, such as the lacewing, ground beetle, and praying mantis also help keep garden pests at bay.

You may recognize the adult lacewing if you ever watch insects congregating near a light at night. The adult does not eat insects; instead it feeds on pollen, nectar, and honeydew (a secretion from aphids). The juvenile form of the lacewing is a voracious predator of aphids and other soft-bodied insects. Sometimes called an aphid lion, the lacewing larvae can eat up to 200 aphids per week. The larvae look similar to lady beetle larvae, except that they are brownish in color. Interestingly, eggs are laid singly on a filament and appear to be suspended in mid-air.

Ground beetles feed on many types of insects, including caterpillars, slugs, and snails. There are over 2,500 different species in North America. They have large eyes that help them see at night and are often black in color. Although they have wings, ground beetles prefer to run rapidly to escape danger. Large jaws help the beetle to catch prey, but be careful because they can also pinch you!

The stature of the praying mantis resembles a person in prayer, hence its name. Sometimes you will see it called a preying mantis, which is also appropriate because the mantis is a predator of many insects. Praying mantids are fascinating to watch. They have large eyes and a head that can rotate in a complete circle, both of which help them to stealthily stalk prey. The mantis has highly modified front legs that help it to grasp prey and well-developed wings for flight. Its green-brown coloration helps it to camouflage with surroundings, but it can slightly alter its color to better match particular settings. The mantis eats many different insects – some good, some bad – sometimes each other. It is fast enough to catch moths, mosquitoes, and flies. The praying mantis lays an egg cluster in the fall that resembles a brown Styrofoam mass on a twig.

I have mentioned only a handful of good insects here. There are many other beneficial insects that do their part in reducing garden pests. Keep your eyes open for these “good guys”. Remember that many pesticides you use will also harm beneficial insects, especially horticultural oils which work as a suffocate. Incorporate plants such as cosmos, nasturtium, sunflower, yarrow, and dill that will attract and provide shelter for beneficial insects. Most importantly, remember a healthy garden will have a balance between good insects and bad insects. For more information on beneficial insects, refer to Clemson University’s Entomology Insect Information Series “Beneficial Insects and Related Arthropods” or call our Center at 919-775-5624.

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