My entomologist friend Richard “Dr. McBug” McDonald likes to introduce presentations on “farmscaping” (creating habitat for beneficial insects to control pests) with the tale of the time in 1996 when I called him to say that ladybugs were controlling the Colorado potato beetles at the Highland Lake Inn Gardens. Richard, then the state’s biological-control administrator, was as close as I could get to a certified expert in organic pest management.
But that day, he thought I was off the deep end.
Not much of anything will eat adult potato beetles, which are more than three times the size of ladybugs. No way!
Then I gave him these details: I had allowed the flower tips of a bolting patch of kale to remain infested with aphids so the beneficials could feast on them. When we finally mowed the kale, we delayed tilling in the stubble to give the beneficials a chance to move on.
In this case, however, they moved over to our adjacent potato patch.
Upon checking my calendar a bit later, I noted that it was time to spray BT (bacillus thuringiensis) on the potatoes to control potato beetles. I asked my co-worker, Seth Krautwurst, to do this.
He soon returned to report that there were virtually no beetles on the potatoes — but there were loads of ladybugs.
Curiosity aroused, Richard did some digging into pre-chemical-era sources and found that, indeed, ladybugs do control potato beetles (by eating their eggs and their first instar, or smallest larva).
By looking before he sprayed, Seth had set Richard and me on the path of innovation, discovery and research (note: Richard does the research, I focus on the discovery/innovation/fly-by-the-seat-of-your-etc. part).
As a lifelong organic grower, I always prefer to let nature work, rather than struggling with the unending succession of imbalances our clumsy manipulations inevitably seem to create. Until this epiphany, however, I had just trusted, lacking an understanding of the workings of effective biological control. But now that I had a concept, insights were everywhere.
Highland Lake’s basic aesthetics-driven garden plan began and ended every section of the garden with an ornamental flower bed and let volunteer flowers remain where they landed whenever possible. This plus the fact that both Highland Lake owner/gardener Treska Lindsey and I liked to let vegetables go to seed for a combination of reasons (aesthetic, spiritual and just plain old curiosity-satisfying) had made us inadvertent farmscapers. Beneficial habitat, or harborage, was everywhere.
Richard is now a consultant based in the Boone area; his comprehensive, excellent Web site provides links to other farmscaping resources (such as ATTRA’s site). Or else just remember that the goal is to attract, feed and facilitate the reproduction of beneficial insects. There’s an amazing diversity of insects in the world, and ultimately — because we need them all in order to achieve ecological balance — they’re all beneficial.
For the purposes of this discussion, however, beneficial insects may be limited to those that either eat garden pests, lay their eggs next to said pests (so their young can consume them), or actually lay their eggs inside the pests. (The latter creatures are called parasitoids because, unlike parasites, they kill their host as they mature.)
The good news is that many of the herbs and flowers we all love are among the most effective farmscaping plants. These include the composites (daisy, zinnia, goldenrod, the Mentha mints, bee balm, most of the common herbs, and the Umbelliferae: Queen Ann’s lace, carrot, cilantro, parsnip, etc.). Parsnip is perhaps my favorite beneficial harborage: When in bloom, it stands up to 7 feet tall, with a cloud of insect life abuzz about it. Volunteer parsnips are now part of my asparagus patch, and as they begin to bloom, asparagus-beetle problems vanish.
Last month I noted the value of weeds as harborage for beneficial insects. These days, they’re my first line of defense. As I sally into my fourth season of market gardening on three-and-a-half acres of very rocky ground, I’m still spending 25 percent or more of my time just preparing soil and installing infrastructure. Tasks such as removing rocks, killing invasive grasses, and building the Great Fence of Celo are keeping me hopping, and I’ve yet to find the time to establish any ornamental plantings.
Each year I’ve started flats of flowers, only to have the demands of my CSA and the downtown farmers’ market overwhelm my good intentions. It’s all I can do to spare a glance at my several flats of mixed flowers as I move yet another flat of veggies to the field. This past Saturday, I stole a moment to plant a flat of desperate-to-go-in-the-ground sunflowers amid a bed of broccoli raab. My rationalization was that the raab will be finished before the sunflowers recover (if they ever do) and overrun the bed. But you can rest assured that Martha Stewart won’t be featuring my farm any time soon!
In the meantime, I’m relying largely on vegetables and herbs allowed to go to seed — that and the diversity of weedy edges and yet-untamed sections of my farm.
In those weedy areas, goldenrod is often infested with a large red aphid by early June. Shortly thereafter, I’ll see Lampyridae (beetles in the firefly family) homing in on the goldenrod and feasting on those aphids. Pretty soon, Pennsylvania soldier beetles and C-mac (Coleomegilla maculata) ladybugs join the repast.
It’s a short flight from the goldenrod to my potato patch, so when they’re finished with the aphids, these beneficials like to dine on the eggs and first instar of the Colorado potato beetle.
This pattern is repeated as the milkweed sets its seed and gets attacked by the large milkweed bug. Drawn by the massive numbers of this colorful bug’s nymphs on the milkweed pods, ladybugs and other beneficials soon begin to find their way to this bug bonanza.
A bit later, burdock sends up its impressive seed stalk, the aphids move in, and the eat-and-be-eaten cycle rolls on. Some of the weeds I touted last month for their medicinal effects also serve as harborage. I’ve already described burdock’s role, but yarrow’s flowers and foliage are even more impressive for the refuge and food they provide to a great array of beneficial insect life. Richard’s research confirms that, along with comfrey, yarrow’s frost-killed remains make one of the very best overwintering sites for beneficials. And I don’t doubt that Richard and I will continue to learn more about the workings of biological control.
The good news is that despite my failings as a flower grower, with the help of just a few purchased biological-control agents (the subject of next month’s column), my farm remains largely free of pest problems. So in the end, I’m the beneficiary of the whole great, self-balancing buzz and dynamics of nature.