You’d think, from the language some pesticide manufacturers use, that most insects spend their days pillaging gardens. The truth, though, is that up to 90% of insects are actually beneficial to the garden, or benign. In addition to pollinating plants, breaking down organic matter, and aerating soil, they eat insects that do like to munch on our prized plants.
Broad-spectrum pesticides kill indiscriminately
Pesticides introduce harmful chemicals to our gardens, and kill both beneficial and harmful insects. When you remove the natural predators from your garden, there’s nothing left to kill the second (and third, etc.) wave of harmful pests that will, inevitably, move in as they pass through your neighbourhood. So now you have another type of insect to deal with. You may find your garden is in worse shape than before because the natural predators weren’t there to protect it.
Attracting beneficial insects
A perfectly mowed lawn is not an inviting habitat for beneficial insects. Gardens that contain a mixture of flowers, shrubs, herbs, and vegetables offer an inviting habitat for beneficial insects, as well as birds, bats, frogs, and toads.
Here’s a selection of bugs that help your garden:
- Assassin bugs are well-named. They eat many different types of bugs and their larvae.
- Centipedes eat pests that live in your soil.
- Ground beetles eat cutworms, caterpillars, slugs, and snails.
- Hoverfly larvae eat aphids, cabbage worms and other small caterpillars, mites, and other pests. Adult hoverflies consume flower nectar, and help to pollinate plants.
- Lacewings eat aphids, whiteflies, larvae, thrips, and mites.
- Ladybugs, ladybirds, and ladybeetles eat aphids, mealybugs, and scale. Their larvae eat mites.
- Spiders, like the yellow garden spider shown above, catch pests in their webs.
- Parasitic wasps lay their eggs inside pests, thus destroying the pest when the egg is hatched.
- Pirate bugs eat a variety of insects, such as aphids, spider mites, and thrips.
- Praying mantis eat a wide variety of insects, such as fruit flies, aphids, cockroaches, crickets, beetles, grasshoppers, and caterpillars.
Bees and earthworms, it should go without saying, are also insect heroes of the garden!
Here’s a selection of pests that may damage your garden:
- Aphids spread viral diseases to legumes, and damage leaves. They have many natural predators, as indicated above, and can be removed with a spray bottle filled with water or a natural soap solution.
- Many types of beetles and weevils can damage plants. The best solution, in many cases, is to remove them by hand, shake them off the plants, or apply floating row covers to your plants.
- Adult Japanese beetles eat flowers and leaves, and their larvae attack roots. The best defence against them is to apply row covers to your plants. You can also try applying a spray made of cedar oil.
- Borers, as the name implies, bore holes in stems, which causes wilting and then death. They attack plants such as melons, cucumbers, and squashes. You can carefully cut them from the stem with a knife and then place the wounded part of the stem under the soil to encourage it to heal.
- Caterpillars may eat plant foliage and fruit, and sometimes their roots. Pick them off and destroy them.
- Earwigs like to burrow in peppers and corn cobs and eat the tips of buds before they flower. There are many ways to trap them, as they like small spaces. They are nocturnal so you can empty the traps during the day.
- Millipedes damage potatoes and may eat seedlings. They like soil that is rich in organic matter, so be sure to regularly cultivate your soil.
- Scale suck on plants and leave tiny bumps. Remove these damaged parts and destroy them. A soap and oil spray is effective against them when they are in their crawling stage.
- Slugs and snails eat leaves and small seedlings. They’re best controlled by birds and frogs, but you can also set traps for them.
- Thrips suck sap from the upper leaf surface, and they may damage flower buds and prevent them from opening.
- Ants aerate the soil and clean up debris and weed seeds, but they also consume the sticky substance created by aphids, and thus transport pests between plants. If the aphids are controlled by the beneficial insects mentioned above, ants should not be a problem.
- Nematodes are microscopic insects. Some varieties feed on insects, and others, such as root knot nematodes and potato cyst nematodes, damage plants. Crop rotation can prevent these from taking hold in your garden.
It’s not as dire as you think
Sure, there are a lot of insects that can harm your garden, but if you rotate your crops, attract beneficial insects and animals, and practice companion gardening, you’re likely to avoid most of them.