OPINION: Doing battle with potato beetles

By Maynard van der Galien

I have a heavy duty shop vac in my garage/workshop that is primarily used to clean out the seed drill after planting. The two-inch hose sucks up the seeds in no time.

This summer, the shop vac served another purpose: Sucking up Colorado potato beetles.

I had a huge infestation of the pesky beetles and I thought if it can pull up grain seeds from down in the mechanism of the machine, it should be able to suck up adult beetles and the larvae bugs from the plants. I didn’t know anyone who had tried it. A Google search wasn’t much help.

I have never had much problem with potato bugs in all the years I grew potatoes. I’d pick the adult bugs off the plants and tear off the leaf if the underside had the yellow eggs attached.

This spring, as soon as the potato plants came out of the ground, there were beetles on them. On windy days when the plants were bent over it was easy to spot the eggs. I was so confident that I had beaten the bugs to their leaf feast.

I understand the life cycle of the beetles and the importance of getting them off the plants right away. Overwintering beetles hibernate in the soil, emerging in the spring. At this point, they do not have enough energy to fly and must walk in search of suitable host plants.

Colorado potato beetle females are very productive and are capable of laying over 500 eggs in a 4 to 5 week period. They are usually deposited in batches of about 30 on the underside of host leaves. Development of all life stages depends on temperature. After 4 to 15 days, the eggs hatch into reddish-brown larvae and feed on the leaves of their host plants. Larvae progress through four distinct growth stages (instars).

The first through third instars each last about 2 to 3 days; the fourth lasts 4 to 7 days. Upon reaching full size, each fourth instar spends several days as a nonfeeding prepupa. The prepupae drop to the soil and burrow in the soil a few inches, then pupate. In 5 to 10 days, the adult beetle emerges to feed and mate. They can go from egg to adult in as little as 21 days. Up to three generations can occur each growing season.

Both the adult and larval forms chew leaves and can completely defoliate an entire crop if control methods are not implemented. Their feeding can greatly reduce yield and in some cases may even kill plants.

A young couple I know moved to the country last year and this spring they worked hard planting a little garden, which they were so proud of. But potato beetles chewed off the leaves of their potato, tomatoes and pepper plants. They bought two different insecticides and neither worked. They are already frustrated gardeners.

Potato bugs have a special talent to adjust to chemical insecticides within a short time and will develop a resistance.

So when I thought I had the bugs nicely under control, the week of hot weather in late June brought an outbreak of larvae on many of my 800 plants. I was stunned. They were stripping off the leaves. I never sprayed any kind of insecticide before as there was never a real need to do that. But now I had to act fast. I thought of the shop vac and luckily my potato garden isn’t far from a shed with electricity. Pulling a long extension cord and carrying the shop vac in one hand, I went up and down the rows sucking up the little buggers. It worked great. Three suck ups in two days and I had the larvae bugs cleaned up.

But a week later another hot spell and I had another infestation. This time it was adult beetles and they were on all the plants. I’d suck them up and they just kept coming. They had to be flying in. Sucking them up was a losing battle. They were stripping the leaves.

I called in reinforcements — a buddy who uses a hand sprayer for cleaning weeds around his buildings came to the rescue. He gave them a shot of insecticide that he had on hand. I’ll be better prepared to do battle with the bugs next year — use an insecticide that works 100 per cent. If it’s available.

Why do I grow potatoes when they are so inexpensive in the stores?
Because my home-grown potatoes don’t go black after boiling them and they are so much better tasting. There is a huge difference.