Bugs you hug

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European chafer beetles, syrphid flies, spiders, ladybugs, aphids, nematodes: which are the good guys and which will destroy your lawn? Allen Garr weighs in

Any given sunny summer weekday that you wander down a city street, you can find a park board worker on her knees at the base of a linden or tulip tree. In her hands she will have small bag filled with several hundred adult ladybugs freshly removed from a refrigerated container.

Before releasing these, she will spray them with sugar syrup. This will ensure they don’t just immediately fly away, but rather will crawl their way up the trunk, into the branches and straight for the masses of aphids that have been sucking sap from the tree and excreting their annoying “honeydew” on parked cars below.
 

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The Vancouver Board of Parks and Recreation has been engaging in this kind of biological warfare for many years now. The city’s arborist, Paul Montpellier, figures it will spend $10,000 this year on buying millions of ladybugs to defend the city’s street trees, particularly the most susceptible linden and tulip.

This particular species of ladybug, Hippodamia convergens, is called the “Tyrannosaurus Rex of the insect world.” Adults will consume 5,000 aphids in their lifetime and lay a thousand eggs, which produce equally aggressive larvae or grubs. These larvae look nothing like their parents, which we have convinced ourselves are cute, almost cuddly; we make up nursery rhymes about them and replicate them in the form of children’s toys.

The ladybug grub, on the other hand is frequently described as alligator-like in shape: it is dark and usually has yellow or orange spots.

But whether you think they are cute or creepy, before you squash a bug, make sure it’s not a bug you should hug. In the battle against garden pests, we can and do get lots of help from insects.

Spiders are among the most reviled bugs. But ask Laura Doheny at David Hunter Garden Centers, and she’ll tell you these eight-legged creatures “do the most wonderful job of cleaning up the garden.”

Syrphid flies, or hover flies, are great predators of aphids. But they can give you pause; they can be mistaken for wasps except for their big heads and multifaceted eyes.

And there are ground beetles, which you may have regularly whacked while you were weeding. Well, believe it or not, their favourite food is slug eggs.

The deliberate use of biological predators to rid plants of pests was once the preserve of organic farmers, when organic farming was considered some kind of weird cult. But as we have come to learn of the dangers of chemical solutions, more people have been looking to bugs for help. And that now includes city folks.

Aside from the possible damage pesticides do to the environment and to your health there is this: “Spraying works,” Paul Montpellier says. “It kills everything.” But, he adds, the first things to bounce back are the pests we were trying to get rid of in the first place. The natural predators don’t recover nearly as quickly.

The city of New Westminster was hit with the European chafer in 2001. It is a small, brown beetle you do not want around. What does the damage is the beetle’s grub, which feeds on the roots of your lawn, killing off huge swaths. If that isn’t bad enough, crows and skunks love to feast on these grubs and tear up the turf to get at them.

The solution recommended by the city was a biological predator called a nematode. The particular nematode species that attacks the chafer grub is a microscopic round worm. The best time to cut these guys loose is in early July. That’s about the time the chafer’s eggs will start to hatch and their grubs will be setting about making a lunch out of your lawn.

In 2005 the City of Vancouver passed a bylaw designed to reduce the use of pesticides. And it appears to be working. Vancouver Coastal Health Authority, which has monitored the bylaw for the past two years, says fewer people are reaching for spray cans. More are buying biologicals.

Most garden shops in the city now carry a regular supply of ladybugs and nematodes in packages just the size you need for a small city lot or backyard garden.

And just remember this: biologicals don’t offer complete pest eradication. They just help keep things under control. Who can’t live with that?