Good Bugs, Bad Bugs

Did you know that landscapes that contain primarily native plants versus traditional landscapes with non-native plants attract 50% more native birds and a nine times higher abundance of rare birds. It also contains three times more butterfly species and double the number of native bees. Our native caterpillars cannot feed on non-native plants. The caterpillars become butterflies and moths and are also a favourite food for the birds.

Beneficial Insects (Good Bugs)

Insects are key to ecosystem health. They are essential for food production and the health of biodiversity. They control other species of insect and contribute to nutrient recycling. They are a food source for other insects and birds. Roles these beneficial insects perform are:

Predators: Eaters such as ladybugs, syrphid flies and hover flies eat aphids, thrips, leaf hoppers and scale. Others such as dragonflies and damselflies eat aphids, thrips, mosquito larvae, adult black flies and deer flies. Spiders eat insect eggs, beetles, aphids, cutworms, spider mites, caterpillars, bud worms and other insects caught in their webs. Lacewings and praying mantis eat insects. Parasitic wasps and tachinid flies parasitize insects as hosts for their larvae. They lay eggs in tomato hornworm, cabbage worms, cutworms, aphids and beetle larvae. Every few years, ground beetles become more important when spongy moths visit.

Pollinators: Bees and wasps are excellent pollinators. Butterflies and moths do their share too. Their larvae are caterpillars so you must be careful what you squish. The beautiful clearwing moths are the adult form of many borers and hornworms.

Nutrient Recyclers: Beetles, fly larvae and earwigs consume decaying plants and animal carcasses to accelerate decomposition and break down organic matter. Ants transport decaying matter to nests to further break it down. Termites digest wood and plant material to break it down. Dung beetles decompose animal feces, enhancing nutrient content.

Bad Bugs

The best defense against bad bugs is to keep your plants healthy. To do this, plant the plants where they like — sun or shade, wet or well drained soil. Give the plants good soil and use mulch and compost. Keep the plants well watered.

In June 2008, the Ontario Pesticide Ban became law. No longer could we sprinkle powder on plants to kill an insect, good or bad, that visited our garden. We gardeners had to adapt and use other, more labour-intensive steps such as:

• Hand picking or shaking into soapy water — pick and squish or dump in soapy water.
• Pruning, water sprays — effective if large infestation of tent caterpillars to destroy the nests.
• Insecticidal soap is only effective if it contacts the insect.
• Pheromone traps are available commercially and are usually for a specific insect.
• Sticky boards are effective for small flying insects such as aphids or white flies. There is a risk that beneficial insects may get stuck also.
• Barriers such as floating row covers — effective in vegetable gardens but must be removed for pollination.

This process is known as Integrated Pest Management (IPM).

Who are the “bad bugs”?

Many of them are non-native and few, if any, of our natural predators want to eat them. For most, hand pick and shake into a bucket of soapy water. Do this regularly for best results.

Japanese beetles and red lily beetles are best picked off regularly (daily) and squished or thrown into a bucket of soapy water. Japanese beetles lay their eggs underground and develop as grubs. Skunks will often dig up your lawn to eat them.

Slugs and snails can be handpicked in early spring. Dump them in a bucket of soapy water. Slugs are very popular with birds, snakes and turtles and earwigs will eat their eggs.

Cutworms like to cut transplants off at ground level. Use barriers around the transplants. I like to use toothpicks close to the stem but toilet paper rolls and newspaper wrap works well too. If you dig up a cutworm, squish it or dump in a bucket of soapy water.

Cabbage worms like to attack all brassicas. If you see white moths flying around your vegetable garden, you can bet they are laying eggs on your plants. To prevent them, use floating row covers all season long. Weight the row covers all around so they don’t blow away and to keep the moths from crawling under.

Potato bugs enjoy potato plants. Hand-pick the insects and knock into soapy water. Rotate your potato plants each year so they are not as accessible to the bugs. If you cannot do that, place a thick layer of straw around the plants, to keep the larvae from crawling up and onto the plants.

Earwigs have both a good side and a bad side. They are predators that eat caterpillars, aphids, mites and slug eggs. They decompose dead plant material to make it accessible to your soil. If you keep your garden too clean, they will start to eat healthy plants.

Aphids are seen as bad bugs but they are essential in the diet of newly hatched birds that are growing rapidly and require protein. Aphids will suck nutrients from the plant. A stem full of aphids looks “creepy”. They can be treated with insecticidal soap or a strong spray of water or by simply running your hand up the stem and squishing them.

Plant suckers such as spittle bugs, leaf hoppers and scale suck the nutrients from the plants. Like aphids, they provide valuable protein.