Yard & Garden Report


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Ladybugs: You Can't Buy Friendship

Ladybugs are great friends in the garden, but don't buy them.

Ladybugs swarming.
Ladybugs are a gardener’s best friend. They serve the role as the “Garden Sheriff,” killing all the bad bugs that threaten our plants. They do a great job of keeping law and order in the garden. A ladybug (more properly called a ladybeetle) can eat as many as 5,000 aphids in its lifetime!

Although they are a great friend in the garden, don’t buy ladybeetles.

The most commonly sold ladybeetle is the convergent ladybeetle. These beetles eat heartily during autumn in the lowland valleys of the Western USA, develop a fat layer in their bodies, and then fly up nearby mountains to hibernate. These beetles sleep together in huge clusters of up to 40 million. While sleeping, these ladybeetles are gathered, refrigerated and then packaged for sale.

The problem with buying ladybeetles is the insects still think they are in the mountains. They have an inborn desire after hibernating to fly several miles down to the lowland valley before they begin feeding again.

Studies have shown that purchased ladybeetles generally fly 20–30 miles after being released, burning up their fat layer before starting to eat new insects. Within 24 hours, less than 1% of the ladybeetles you release in your garden will remain—maybe these ladybeetles have broken wings. Within 48 hours, you will have difficulty finding any ladybeetles. For goodness sake, gardens in the next county may benefit more than your garden from these ladybeetles!

In general, buying predator insects has its limitations, especially since you need to have pests in your garden for the predators to eat. Instead of buying ladybeetles, focus on keeping your plants strong so they can withstand minor pest infestations. Short-lived and relatively safe insecticides such as neem, spinosad, Bacillus thuringiensis and soaps are available when needed.

Written by Tom Kalb, Extension Horticulturist, North Dakota State University. Photo courtesy of Thomas Hawk.

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