Taking stock of lessons learned and new friends in 2010, one of my favorite highlights was getting to know entomologist Beverly Gerdeman from our local Washington State University Mount Vernon Research Center. She first made contact with us after receiving funding for a WSDA cut flower specialty crop block grant. Ever the opportunists, we graciously welcomed her to visit our farm and photograph insects.

We ended up making friends in the process and seeing more deeply into the abundant insect world that our farm supports. She learned that pretty much all flower farms in the Pacific Northwest battle the same little devils: thrips and aphids. We learned more about who eats those little devils and the blur of grey between “good guy” and “bad guy” in the world of insects.

Syrphid flies, also known as hoverflies, mimic the look of a bee, but have just one pair of wings and can be seen hovering around blooming flowers where, like bees, they feed on nectar and pollen, meaning that adults may also play a role in pollination. Adult females lay individual eggs on the backs of leaves where aphids are present. Syrphid fly larvae look like small, legless green worms and each one can consume as many as 400 aphids. They eat thrips, too. With as many as seven generations in one season, these are definitely good guys. I see them all over the farm and they don’t seem to favor one particular crop.

Lady beetles were first named “Bug of Our Lady” in medieval Europe where it was believed they were a divine gift for crop protection. Hmmm, I wonder about that in early spring when our less-than-airtight old farmhouse is infested with hundreds of adult beetles while some hoophouse crops seem out of hand with aphid problems. Then about late June, I notice veritable armies of lady beetle “dragons” and adults, especially on the dahlia crop. Last year, because we were too busy to get out there and spray with soap, I observed entire plants going from infested to clean in a matter of a few days. Literally, we wiped off the aphid exoskeletons and sold the flowers! On our farm we commonly see lady beetles attacking aphids on fennel, a member of the carrot family, so we keep a fennel trap crop to encourage larger numbers of these divine vacuums. I have noticed adult lady beetles, along with wasps and hornets,  feeding on orchard fruit in the fall, probably stocking up on sugar to make it through winter’s hibernation.

Though they’re not as common in the field as lady beetles, I always love seeing adult lacewings (above left), both green and brown. It took Beverly, though, to show me what a lacewing larva (above right) looks like. Like syrphid flies, adults feed on nectar, pollen and honeydew, laying eggs on plants where aphids are present. It’s the larvae which are the meat eaters. Mobile and dragon-like, they devour as many as 200 aphids a week during their two- to three-week development stage. That’s up to 600 aphids per individual. And, they don’t just kill, they seize their prey with large, sucking jaws and inject a paralyzing venom. This critter is definitely hired!

Andy, our beloved and only full-time employee, is allergic to hornets (we’ve got a doozy of an emergency room story from a few years ago) so I carefully classify hornets and paper wasps as good guys. Paper wasps are usually docile to humans and prefer caterpillars, including cabbage moth. They often build their open paper nests in the eaves of our greenhouse and on the woodwork in our hoophouses. Adults feed their developing larvae a highly nutritious mixture of regurgitated caterpillar blood and nectar.

Other kinder, gentler meat-eaters include the solo-dwelling mud daubers and a number of parasitic wasps. Baldfaced hornets, on the other hand, are highly aggressive and we have to remove nests that are anywhere near high traffic areas. Fortunately, the farm is a big place with plenty of wild borders and areas so nature can strike her own balances with these highly important members of the food chain.

Dennis wrote a wonderful children’s song about arachnids to the tune of “When Johnny Comes Marching Home” a few years back. Thanks to him the words “They are a hungry carnivore, with poison fangs they’re hunting for insects, worms, THEY EAT FRESH MEAT!” are permanently stuck in my head.

The photo on the left (above) shows a beneficial crab spider ruthlessly devouring a beneficial honeybee. Shades of grey. Crab spiders do not build webs. Rather they change color to camouflage themselves on flowers (above right) and attack visiting nectar-seeking insects. They kill quite a number of pest flies and mites—and sometimes the “good guys”. I’m intrigued by their ability to change color and will be keeping an eye out next year to see how many different colors they can assume.

All true bugs, Beverly informs me, have sucking mouthparts. This makes them potential pests for flower crops, like the above pictured Lygus linealoris, also known as tarnished plant bug. Lygus aren’t terribly plentiful on our farm, but heretofore, I’ve always thought they were eating thrips. They look like a larger version of another true bug, Orius, which is a highly beneficial thrips eater. According to Beverly, “Tarnished plant bug doesn’t eat thrips at all. It is a pest of composite flowers (asters, mums, impatiens and marigolds) and can vector viruses with its saliva injected into the flower tissue. Flowers from damaged buds sometimes fail to develop on one side or abort. Regarding damage on your dahlias, could it be so subtle that it is not visible? Insects can be distributed in a spotty pattern even within a host plant row so it is important for flower growers to inspect their crops as often as they can.” Looks like we’ll be doing some more careful monitoring next year.

Since, during their adult phase, many insects feed on pollen, nectar and other sugar sources, what better place to live and reproduce than on a flower farm? Some, I have noticed, are partial to a particular flower. Half-inch long, slender orange soldier beetles, for example, hang in rampant, reproducing clusters from the Italian sunflowers (Helianthus debilis ssp. cucumerifolius), and disperse themselves around the farm to feed on aphids. Their larvae are mobile and hang out around the soil surface in leaf litter and such, feeding on insects, worms and, get this, slugs and snails!

Probably our best visible thrips predator is the true bug, Orius. They’re smaller than the characters pictured above, approximately 3/32″ long — bigger than a thrip and sometimes so numerous on our dahlias postharvest that they can be a problem. Beneficial or not, the bugs need to stay on the farm. To remove both Orius and thrips at harvest, especially on dahlias, we dip the flowers in a solution of 1 ½ oz. Pyganic to 2 gallons of water. Dip. Let sit one minute. Dip again in plain water and dry with a gentle fan. This method was shared with us by Marc Kessler of California Organic Flowers. It works great to remove small numbers of aphids from early-season anenomes and ranunculus as well. Other flowers such as sweet peas and campanula suffer from a dipping, so always test.

Out in the field our policy is to do as little insecticide application as possible. We live with some losses and there are some crops we just can’t grow, especially early in the growing season before the “good guys” are fully up and running. Occasionally we purchase and release beneficial mites and insects. However, with shipping costs, the release of live beneficials is expensive for a small and diversified operation like ours.

When we do need to spray for pest insects, we use only OMRI-certified sprays and choose carefully from that list because we do not want to disrupt balances that we barely understand. Although many variables are at play, we suspect that our sustainable growing practices combined with the diversity of crops we grow has led to increasingly rich beneficial insect populations. Each year the thrips and aphids, those little spawns of Satan, seem to be less of a problem. But hey, just one more detail from Beverly, “…there is such a thing as beneficial thrips…”

During the growing and harvest season, it can be so crazy busy that it’s hard to focus on anything but taking and filling orders, and keeping the crops watered. We appreciate knowing that we have a force of unpaid labor out there helping us.  Thanks, Beverly, for letting us see our world through your compound lenses.

Photos courtesy of Beverly Gerdeman, Washington State University Mount Vernon, Northwestern Washington Research and Extension Center.

Diane Szukovathy

Jello Mold Farm

Diane Szukovathy Jello Mold Farm Contact at [email protected]