Insects: our tiny garden friends

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.

Good bugs

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!

The bad

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.

The variable

  • 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.

Pollen nation: More than just the land of honey

Pollination is the process by which the pollen grains from the male part of a flower (the anther) are transferred to the female part of a flower (the stigma). Plants may self-pollinate (the pollen grains fall directly onto the stigma of the same flower) or cross-pollinate (the grains from one plant from fall onto the stigma of another flower).
Plants such as corn rely on the wind to perform cross-pollination. Here, the wind blows the pollen from the tassels at the tops of the cornstalks onto the silks at the tops of the cobs. If you plant corn, you’ll want to do so in blocks rather than a single row, because wind rarely blows straight down.
80% of flowering plants, though, rely on animals to make their pollen deliveries for them. Hummingbirds, butterflies, and even bats (in tropical countries) are integral to pollination. Monkeys, lemurs, possums, rodents and lizards have also been known to pollinate some plants. Bees, though, are the most common cross-pollinators.

Busy as a bee

When a bee lands on a flower, its feet slip into the groove that holds the flower’s pollen sacs in place, and it lifts them up and carries them away. When it lands on another flower, it deposits some of the pollen, thus completing the process of pollination. While the bee is feeding on its nectar, it is ensuring pollination occurs and a fruit or vegetable is born–and so it is feeding us as well!
As you can imagine, if we didn’t have bees, we’d have a lot less to eat! Here are some of the plants that bees pollinate: https://en.wikipedia.org/wiki/List_….
Unfortunately, bee populates are dwindling. There has been a lot of scientific research into their declining numbers; among the reasons considered are neonicotinoids, invasive parasites, climate change, decline in their diets, and cell phone radiation. One species was added to the endangered species list last month: https://www.scientificamerican.com/….

Helping bees help us

There are a few things we can do to make our gardens friendly to pollinators such as bees:
  • Don’t purchase entomopathogenic nematodes. They are used as biological insect control, but in addition to killing “pests”, they kill large numbers of bees: https://www.ncbi.nlm.nih.gov/pmc/ar…. Read the label when you buy plants, because some plants have been treated with these nematodes and thus are carriers.
  • Plant flowers that bees love: http://fafard.com/terrific-flowers-…
  • Build a bee house or a bee bath: http://www.davidsuzuki.org/what-you….
  • We know that dandelions are considered unsightly, but they are the first spring meal for bees. Consider leaving them in the ground for our insect friends.

Fun facts

A honeybee can fly 15 mph. Its wings beat 200 times per second!