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COLUMN: Plant for bees, butterflies, other beneficial insects

Have you ever wondered why your plum tree was full of blossoms, but bore no fruit? Where were the pollinators?
Charles Schroder
Columnist Charles Schroder

Scientists estimate we have about 20,000 varieties of insects. One plant nursery estimates that between 97-99 per cent of the insects are either harmless or beneficial. Beneficial insects pollinate flowers, vegetables, and fruit trees. Others help to keep pests under control. Many insects are food for birds. Unfortunately, many pesticides and lawn chemicals kill all insects, seriously impacting the productivity of our gardens, harming our environment, and reducing the number of song birds.

Have you ever wondered why your plum tree was full of blossoms, but bore no fruit? Where were the pollinators?

There are many pollinators in the urban garden. In Alberta, there are more than 300 species of native bees, with at least eight main species of native bees, including bumble, mason, digger, cuckoo, miner, masked, and leafcutter bees. Other pollinators include hover flies, butterflies, moths, wasps, flies, ants, midges, beetles, and — believe it or not — mosquitos.

Bees are the most important, ensuring your fruit trees and berry bushes fruit, your flowers seed, and squash and cucumbers set. To attract bees, provide food in the form of a wide variety of flowers, fruit trees, and berry bushes. In the spring, pollinators are attracted to poppies, fruit trees and berry bushes, lilacs, and pasque flowers. In the summer bees like the butterfly bush, coneflowers, dahlia, fireweed, phlox, sedum, and sunflower. In the fall bees go to aster, goldenrod, and black-eyed susan.

Solitary bees such as the mason bee are important pollinators. They live alone, do not sting, and make their nests in small cavities in mid to late summer. The eggs hatch in the spring.

A bee hotel provides a place for solitary bees to lay their eggs. The simplest version is a 20-centimetre-deep box with sides, a back, a roof to keep out moisture, and an open front. Place tubes of paper or cardboard in the box, or rounds of wood with holes of many different diameters drilled into the rounds in which different sizes of solitary bees can lay their eggs. Do not use plastic straws or tubes; moisture is trapped and the eggs or pupae will mould and rot. Look up different designs on the Internet.

Attach the hotel to a fence or post at least a metre above the ground, facing south or south-east. Clean out the tubes and holes each spring with a pipe cleaner after the eggs have hatched and the bees have emerged. If you don’t, your hotel becomes a haven for mites, fungus, and other parasites and you will have dead bees. 

Another garden delight are pretty butterflies, in oranges, reds, mauves, and even whites. There are 26 varieties in Alberta ranging from the white cabbage, tiger, swallowtail, mourning cloak, fritillary, to the melissa blue. Butterflies are also pollinators.

If you avoid harmful pesticides, your fruit trees and berry bushes will fruit, your flowers will seed, and your squash and cucumbers will set. Nature is magic. 

Charles Schroder is a St. Albert resident and an avid gardener.

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