Using beneficial insects in your vegetable patch is an excellent way to control pests. And, if you are as fascinated as I am about insects, it’s like Xmas when it comes time to release them. There are a lot of different insects available to control a wide range of pests. Lady bugs, predatory midges and mites, nematodes, parasitic wasps, are just a few of the good insects that can protect your garden. There is a lot to discover and learn when using beneficial insects and here are few insights I have to share.

Why use Beneficial Insects

The vast majority of the insects, fungi, and friends that are living in a garden are completely harmless to anyone. They’re busy doing their own thing and it doesn’t involve us or our plants. There are a small handful of trouble makers, and these are the pests that eat our gardens. The conventional method of controlling pests often involves the use a broad spectrum insecticide, which may kill the pest but also can do significant damage to the surrounding ecosystem, throwing things out of whack and precipitating further pest outbreaks. One the biggest benefits to using beneficial insects is that they are host specific, meaning they only attack the pest, and do not wipe out every living thing in the air, soil, and/or water. Remember, the vast majority of life in the soil is not doing you any harm, in fact it this very collection of creatures that are creating a stable, productive, and healthy soil. When a broad spectrum pesticide is applied it can wipe out a lot of the life, including the pest’s enemies. When the ecosystem recovers, the pest population emerges first, followed by the beneficial insects, and this delay opens up space and time for a pest to thrive. This results in another explosion of the pest population. If you’re using a broad spectrum pesticide, organic or not, to control pests, it’s easy to fall into a routine, calendar spraying, because that’s all that seems to work. Fortunately there are alternatives.

A different mind set is required when using beneficial organisms to manage pests. You have to plan ahead and anticipate the problem. You need to take time to study the insects you find and learn to properly identify them. Each insects or disease has its own story. Research it and you may find the pest can be managed with another insect, or through simply modifying the irrigation or fertility.

Plant trap crops and host plants that will support your predators. Trap crops are essentially sacrificial crops that are grown in hopes that they become infested with a pest. This infestation provides food for the predators, enabling the predator population to grow rapidly and remain established in your garden. Lupine is commonly grown to attract the lupine aphid. This aphid does not feed on peppers or cabbage, but provides a healthy food source for your predators. I have a big clump of Shasta Daisy which gets attacked early in the year by aphids. I facilitate the aphid infestation by over fertilizing the daisies with lots of compost, resulting in succulent growth that is attractive to aphids. By early summer the daisies are covered with lady bug pupae feeding on the aphids, and my surrounding garden is relatively aphid free.

Host plants can be grown to encourage predators to live in your garden. By growing a wide variety of these host plants in your garden you will be providing habitat, shelter and food for many beneficial insects. Low growing plants like thyme, mint and rosemary provide cover for predator ground beetles. Flowers on crops like dill, fennel, clover, chamomile, daisy and yarrow can provide nectar and pollen that many beneficial insects require in their diet.

Many of the beneficial insects that are available are used primarily in greenhouses where they are confined and cannot fly away. In an open garden area such as your typical backyard there is no guarantee that any flying predator will stick around. Growing host plants and trap crops will encourage them to stay and provide an environment conducive to their reproduction.

If you order some beneficial insects that you plan to release into your garden, remember that they are living creatures and need to be handled with care. Extreme temperatures, humidity or excess sunlight can kill off your predators before you’ve had a chance to release them. Nematodes, commonly used to control grubs and caterpillars, are a good example of how sensitive some beneficial insects can be.  These microscopic round worms are very sensitive to sunlight and require a moist soil to survive, so apply the nematodes in the evening to a moist soil, and water them in. Other predators such as predator midges can be susceptible to wind. In general release them up wind of the garden, and avoid releasing on extremely windy days.

The timing of release for many beneficial insects is important to consider. If you release them too early and there is an insufficient population of the pest to keep them fed, the beneficial insects with fly away, or starve. If you wait to long, the pest population explodes and causes crop damage. This is why a trap crop is useful, because it provide some food for the newly released predators to feed on and encourages them to become established in or near your garden.

Ordering a box of lady bugs, predatory mites or wasps and then releasing them into the garden can be a great way to teach kids about the amazing world of insects that live all around us. There are a variety of suppliers throughout Canada and many nurseries also handle some beneficial insects during the growing season. Using bugs to control bugs is a proven method of pest management and a fascinating and rewarding way to grow a healthy landscape.