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Controlling the Red turnip beetle
by John Harmon
October 6, 2002

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This summer wasn't as bad for bugs as last year when most gardeners around Whitehorse had problems with an infestation of Red turnip beetles. I complained about them eating all the Brassica crops in my garden. A lady sent me an e-mail early last spring that just got to me now. It's been floating around out there in cyberspace all summer! Here's part of what she had to say.

"I have been gardening in the Atlin/Tagish area for the last 32 years. Those pesky red beetles have only been around for the past 12 or so. We hand pick them (my kids did science experiments with them when they were young). I have found that planting Siberian wallflowers, English wallflowers and Alyssum acts as an attractor crop. You simply plant them as far away from your cabbage etc as you can get. Then on warm days go out every couple of hours and pick then off." She went on to say "Nothing seems to eat them either. We tried feeding them to chickens but they aren't interested. I have never seen larva's but found out they like to lay their eggs under bark (like the peeling bark from the logs my raised beds are made from). Good luck with them this year. By the way we have already eaten eggplant, red mini-peppers and 8 tomatoes this spring also quite a few cucumbers, couldn't resist the urge to brag! Happy Gardening, Claudia MacPhee"

This bug is known as Entomoscelis americana or Red turnip beetle. It is native to North America and relatively abundant throughout the Aspen Parkland Region of the Canadian Prairies and the Peace River District of Alberta and British Columbia. It's fairly new to the Yukon in great numbers.

Eggs are deposited from early August to late October near the plants on which the adult beetles feed. The reddish-brown, oblong-shaped eggs are laid singly or in clusters in shallow crevices in the soil, or in loose soil under soil aggregates, leaves or other debris at a depth of less than one-quarter inch. Within two to three weeks of being deposited, the eggs are mature. They remain dormant until late March to early May, hatching in spring after snow has melted but before crops are seeded.

Cultivation is an extremely effective means of reducing Red turnip beetle eggs, larvae, and pupae. Cultivation after harvest buries the eggs and when they hatch, the larvae are unable to burrow out of the soil. Fall cultivation may cause 75-100 per cent mortality of newly hatched larvae the following spring. I have been tilling up the garden in both the fall and the spring and this year had fewer bugs.

There are about 2,500 known species of ground beetles in North America. These active insects are usually found on the ground under rocks, logs, leaves, bark, decomposing wood and other debris on the ground. To help control them remove objects where beetles can hide such as leaf piles, old boards, rotting logs, stone piles, firewood piles, etc.

Millions of beetles are captured annually in mechanical traps. These traps have a scent to attract the beetles. This method is an easy and inexpensive way to reduce beetle populations and curtail egg lying. Under favorable conditions, a trap will capture about 75 percent of the beetles that approach it. Because the traps actually attract more beetles than they capture, be sure not to put traps near your favorite plants. Put traps at the borders of your garden away from plants the beetles may damage. Traps are most effective when many of them are spread around the garden. The traps should not stay in place year 'round because the lures inside get stale. Beetle traps are available at garden centers. 

You can make your own trap for these nasties. It's made from a nine inch length of one and one half inch PVC pipe that contains a piece of eight inch by 11-inch corrugated cardboard that has been rolled up so that the eight inch length is inside the pipe. Red turnip beetles and larvae will crawl between the cardboard layers to hide. Leave the ends open and when they have been out in the garden and fill up with bugs just shake the cardboard out into the burn barrel to get rid of the little pests. Refill with new cardboard and it's ready to catch more.

Now is the time to get out there and till up your garden and you too will have fewer bugs to deal with next summer.

John Harmon owns and operates Tropicals North. Write to John at The Real Dirt, c\o 211 Wood St., Whitehorse, YT., Y1A 2E4 or e-mail tropnorth@polarcom.com.

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