Good Bugs in the Greenhouse

I was mid-way through a shower the other morning when I realized I wasn't alone. (Not to worry. This is a family-friendly blog. Please read on.)

My showering companion that day was one of the best friends a gardener can have. It was elegant.... a beautiful pale green, with veined wings and tiny bulging eyes that don't miss a trick. If you guessed "green lacewing," you're right.

Green lacewings are a welcome and common sight in environmentally-friendly Colorado gardens in warm weather. But where did this guest come from in the middle of winter? It took me a few minutes, then I figured it out. Kris, Tagawa's co-director of annuals, had issued a personal invitation. Here's how.

Kris is an organic gardener at home, and is always interested in finding new ways to grow and garden organically at Tagawa's, too. Last October, she began what I like to call "Tagawa's Great Lacewing Experiment." And so far, that experiment is a resounding success! The adult green lacewing sharing my shower the other morning was testimony to that success. It had apparently hitched a ride home with me on one of Tagawa's poinsettias.

Last fall, Kris turned loose about 5,000 live lacewing larva, the voracious bug-eating stage of the insect that emerges when the lacewing eggs hatch. Not long afterward, Kris brought in small cards about the size of a bookmark that were coated with lacewing eggs embedded in lacewing food. In the warmth and humidity of the Tagawa greenhouse, the eggs hatched out quickly. These new larvae didn't have to go far for their first meal since Kris had strategically placed the cards throughout the houseplant department where insect pests can be a challenge this time of year.

Once the larvae morph into adults, Kris supplements their diet with a special mixture of honey, bee pollen and brewer's yeast brushed onto cards suspended throughout the houseplant department. Lacewing larvae will eat 200 insect pests a week, which is why gardners love them. But the adult lacewings aren't eating machines like the larvae, so they thrive on the extra food that Kris gives them. It was one of these well-fed adults that came home with me.

But why does Tagawa's need insect control in the greenhouse? That's easy. Any "healthy" greenhouse, like any "healthy" landscape, will have its fair share of insects. The goal is not to have zero insects. The goal is to keep insects in check... or more specifically, to help Mother Nature keep them in check, to a point where damage is insignificant. And that's exactly what Kris' lacewings are doing.

She says the results were "immediate." Within days of introducing the lacewings, Kris says the number of mealy bugs, aphids, thrips and spidermites on the houseplants plumeted. Kris estimates that the level of "bad" bugs dropped by eighty percent without an ounce of chemical insecticide being used. In fact, with the green lacewings on duty, using potent insecticides in the greenhouse is prohibited. Some soaps and botanical oils can be used without harming the "good bugs."

This speaks to one of the big problems gardners create when they "spray for bugs." Strong chemical insecticides kill the damaging bugs and the beneficials. And since the "bad" bugs tend to reproduce more quickly and more prolifically than the "good" bugs, it's the bad bugs that get the upper hand. The gardeners, and Mother Nature's balance, have a hard time catching up.

Is Kris likely to increase her cast of beneficial characters as spring approaches? Indeed she is. She's looking at a wonderful little critter called a "mealy bug destroyer." Guess what they eat.

Inviting beneficial insects into the greenhouse is in keeping with Tagawa's commitment to sustainability, and to a leadership role in the green industry. Tagawa's was the first Veriflora Certified Sustainable garden center in the country. Sustainability and earth-friendly gardening practices are a priority for Tagawa's. We invite you to wander through our houseplant department and see if you can spot one of Kris' lacewing "launching pads" suspended over the plants. They're pretty interesting.

And what about the little green guest I found sharing my shower? I tucked it into a small plastic tub, gave it a tissue for something to hang onto during the ride, and released it in the middle of Tagawa's houseplant department. It took the elegant little bug all of half-a-second to take off and fly up into the greenery. Here's hoping its offspring will be chowing down on the pesky bugs any day now.