The Integrated Homestead: Insect Threats and Insect Diversity

“The Integrated Homestead”

Once our soil improvement efforts take hold and our crops begin to thrive, we inevitably make the unsettling discovery that somebody out there likes our crops as much as we do. What do we do about threats to our harvests from herbaceous insects?

The Problem with “Shooting from the Hip”

The response we’ve been conditioned to, most likely, is to seek out something potent to kill those guys. Monsanto, Cargill, and their minions stand ready to help us in that quest, as indicated by the more than 550,000 tons of synthetic pesticides sold in the United States every year. But seeking a simplistic, one-for-one solution to insect competition is enormously destructive. Almost all pesticides are “broad spectrum” in their effect, meaning they kill all insects who eat them or with whom they come in contact, not just the target species.

In case your response to that last statement is “So what?”, let me tell you a little story. I have always been an “organic gardener,” but early on in my gardening I thought that meant it was okay to kill problem insects with “organically approved” pesticides like rotenone. I found Colorado potato beetle one of my most difficult “pests” to deal with, and dusted with rotenone several times per season to bring in the crop, always just barely keeping the surging population at bay. Fortunately, even a bonehead like me is capable of learning; and as I learned more about insect diversity, it bothered me to think that my use of rotenone in a death struggle with potato beetle was knocking out as well lady beetles, praying mantises, lacewings, ground beetles—“Hey, didn’t someone say those are the good guys?” (In military lingo that’s called “collateral damage.” Or maybe “friendly fire”?)

At the beginning of one season, therefore, I took a Great Vow: I would not use rotenone in the garden, even if it meant losing the entire potato crop. So I was overwhelmed by potato beetle, right? Actually, I found five potato beetles in the potato patch the entire season. I knew by that time that insect problems can swing wildly from one year to the next, so at first assumed that I was just enjoying a lucky season for potato beetle. Until I bumped into my neighbor from across the road, whose garden was about seventy-five yards from mine. “My, my!” she wailed, “ain’t these potato bugs just awful. I dust and I dust and I dust, and I’m still out here every day, pickin’ ’em off by hand!”

You’ve read stories about that Zen “moment of enlightenment”? In that moment I could see the complex, teeming pathways of insect life over my garden, yearning to come into balance. And no, my good fortune was not just the luck of a single season: In almost two decades since, my experience with Colorado potato beetle in every season has remained exactly the same. Indeed, it has become the easiest of all insect competitors in my garden to deal with.

It is precisely the enormous diversity of insect species which offers a possibility for beautiful balance, in which insects who can be a problem for us develop problems of their own—surging populations of insects who want to eat them. A reflexive toxic response to insect pressure tears great holes in the fabric of insect life. It kills insects, yes, but it kills most of all the possibility for that balance. Indeed, the adoption of any strategy based on killing insects is flawed. Remember, when we remove any part of a natural system, we inherit its work. We should beware imitation of a toxic agriculture which has shown itself so little capable of taking on that task.

Planting for Insect Diversity

How can it be that, in a single season, potato beetle ceased being a problem for me after I stopped doing anything at all to fight it? A lazy gardener like me always has edges of “jungle” creeping around the edges of my efforts to cultivate. Doubtless there were lots of flowering weeds that I just hadn’t gotten to, all around the garden. Once I stopped knocking down my potential friends with rotenone—lady beetles, lacewings, praying mantises, assassin bugs, parasitic flies and wasps, ground beetles, spiders of all types, big-eyed bugs, dragonflies, aphid midges, damsel bugs, parasitic nematodes, predatory mites and thrips, rove beetles, tiger beetles—those islands of flowering plants started doing what they most want to do: provide food, shelter, and a place to meet and mate for their insect allies. (The insects are a lot like us, really—what they have foremost on their minds is: food, shelter, and sex.) With that natural alliance restored, those insects began feeding on potato beetle eggs. And the rest, as they say, is history.

Flowering plants—different species, with a variety of flower shapes and sizes, blooming at all parts of the growing season—are the key to the robustness and diversity of insect populations, and hence to balance. The take-home lesson here is not that you should imitate a lazy gardener like me and allow a jungle of flowering weeds to proliferate around the perimeter of your cultivated areas. Rather, you can establish habitat plantings of flowering annuals and perennials in and around the garden and orchard. Place the perennials throughout the garden, rather than off in their own little fiefdoms. As for the annuals, I grab ripe seedheads of umbels like dill and cilantro, and walk through the garden, beating them against my hand to scatter the seeds. The following season, if a dill or cilantro plant pops up where it’s inconvenient to my plans, it’s a weed, and I pull it out. But if it fits with the crop plantings I am making in that bed, I welcome and honor it for helping out my insect buddies.

We considered earlier the role of cover crops in soil fertility. Flowering cover crops like crucifers (e.g., turnip or mustards), buckwheat, and clovers also give a tremendous boost to insect diversity.

I said we should encourage flowering plant diversity “in all parts of the growing season,” but actually we should be concerned for insect diversity in the winter as well. Learn to recognize the tan “frozen foam” egg cases of praying mantis, and be careful not to discard them when doing fall clean-up chores. With some plants, we should forego that fall clean-up altogether: The dead leaves of comfrey look rather messy as the plants go dormant, but they offer critical shelter for spiders and overwintering insects.

Multi-functional plantings

How fortunate it is that making permanent plantings for insect habitat can serve multiple functions:

Culinary herbs: Flowering culinary herbs such as rosemary, thyme, basil, dill, and sage provide spice to our meals while encouraging insect diversity.

Medicinal herbs: I urge every homesteader to learn more about flowering plants that have medicinal uses. The tendency is to think either that home herbal remedies are just “folklore” with no real effectiveness, or that herbal lore is so complex and mysterious that we simple gardeners couldn’t possibly master it. Neither assumption is true. The effectiveness of plant medicines has been scientifically proven time and again, as indicated by the use of plants such as wild yam to develop more than one potent pharmaceutical drug. Meadowsweet and willow unquestionably contain salicylic acid, and have analgesic effects like aspirin (but with fewer side effects). And when we learn just how many common plants have been used medicinally, we start to think that the subject is not so arcane after all. For example, the California School of Herbalism compiled a list of thirty medicinal plants that could provide the practicing herbalist “a central core of tonic and therapeutic plants.” The list includes blackberry, calendula, cayenne, German chamomile, comfrey, dandelion, fennel, ginger, mullein, stinging nettle, peppermint, plantain, willow, yarrow, and yellow dock. How easy is that—some of these plants are common weeds, for heaven’s sake!

Fertility plants: Many of the plants grown for their contribution to soil fertility provide food and shelter to insects as well. I find more places all the time to incorporate dynamic accumulators like comfrey, dandelion, and yellow dock, as well as nitrogen-fixing legumes such as clovers and alfalfa.

Feed for livestock: Some flowering plants that boost insect diversity can also provide fodder for livestock. Comfrey is an excellent example, either cut and fed fresh, or dried as a “hay” for winter use. I have experimented with stinging nettle as well, for a mineral-rich dried winter feed. The abundant tubers of Jerusalem artichokes can be used to feed pigs.

Ground covers: There may be areas in the homestead where we can establish flowering ground covers other than grasses which protect the soil and boost its fertility, while encouraging insect diversity. Michael Phillips, author of The Apple Grower: A Guide for the Organic Orchardist, has concluded that grass is not a good ground cover for an orchard, so has established a diverse mix of comfrey, crucifers, and other flowering plants under his fruit trees. Much of my work in the forest garden so far has been the laying down of “kill mulches” to smother the former grass sod, in preparation for planting more useful flowering ground covers.

Note that some plants play many of the roles above, in addition to encouraging insect diversity. Baptisia tinctoria (wild indigo) fixes nitrogen in the soil, is medicinal—and is beautiful. Many of the flowering herbs are both culinary and medicinal. Clovers fix nitrogen and can be cut for mulches, composts, or green feed or hay for livestock. In addition, red clover is an important medicinal. Indeed, a plant like comfrey serves all six of the functions discussed above. You will discover many others as you bring new plant friends into your increasingly complex homestead ecology.

Other Strategies

Hand-picking

Every time I tell my success story about Colorado potato beetle, I add that these days, I find so few CPB’s that it is possible to prevent a population build-up simply by hand-picking the few adults that do show up and Squish! Inevitably someone asks: “But I thought you said any strategy based on ‘killing insects’ is a mistake.” But hand-picking and killing insects that could become harmful if permitted to start raising families is a purely local event that has no deleterious effects in the broader insect community. A strategy of Squish! is entirely different from “going nuclear” and blasting our backyard ecology with toxic substances more appropriate to chemical warfare, in reckless disregard of the consequences for the rest of the season. And next season. And the one after that.

Hand-picking sounds like a difficult and time consuming task, but it does not have to be. The key is to do what we should be doing anyway—strolling daily through the garden, saying hello and seeing how everyone is doing. On those daily visits, taking out those first opportunists will go a long way toward preventing a vigorous population build-up, giving our insect allies time to get involved as well, for example by eating eggs of herbaceous species.

Succession planting

We must be prepared for the fact, however, that hand-picking will not provide sufficient control of some insect species. Which ones are the “toughest,” most aggressive to deal with will vary with your own particular conditions. For me, the squash bug is one of the hardest of all insect competitors to control.

One possible strategy is simply to give up all idea of control, and to rely on the natural vigor of the crop plants to produce for us despite insect pressure. With summer squash, for example, I often plant an initial crop, and harvest from it while it is increasingly assaulted by squash bugs (whose reproductive potential is awesome). At a certain point, the plants succumb—but by that time, I have a succession planting of squash elsewhere in the garden (preferably as far as possible from the current breakout zone). These plants produce and succumb in turn. Fast-growing species like squash can give three or more successions in a single season. It may seem an odd strategy—bowing to the impressive reproductive capacity of a tough insect competitor—but I can eat squash throughout the season all the same. And it’s not contaminated with toxic residues.

Dancing with more than one partner

Another insect whose presence I know I will simply have to accept in my garden is the Mexican bean beetle. Since I can’t defeat this busy, prolific beetle with hand-picking, I grow two (or more) varieties of beans in a variation of succession planting: I plant a patch of bush beans like Contender, at the same time as I plant a bed of pole beans like McCaslan. The faster-growing Contenders start setting pods early, and I am able to get many pickings from them as the bean beetles obey the commandment to “be fruitful and multiply.” At about the time the Contenders give up the fight, the McCaslans are setting pods. The bean beetles happily migrate into them as well, but the McCaslans simply have more resistance to them—they continue to produce heavily for me even while hosting a busy population of the beetles.

Dodgeball

It’s possible simply to side-step the main threat from a particular insect—that is, to plant outside its main season. Last year, for example, I didn’t even try to grow summer squash early on—I just ceded that part of the season to my rival, the squash bug. Then in late August, I planted zucchini and yellow squash. By that time, the squash bugs had apparently made commitments elsewhere—I harvested many a fine dish of squash for over a month, seeing in the process only the rare lost and lonely squash bug.

Physical barriers

Physical barriers can give the edge to crop plants when they are young and tender and not yet well established. At this stage, for example, brassicas are vulnerable to cutworms, who can be quite destructive. A collar made from a strip of cardboard, pushed into the earth around each seedling, keeps the cutworms at bay until the plants have grown thick, tough stems immune to attack. Spun-bonded row covers are light fabrics used to protect beds of young plants from insects, while permitting passage of sunlight and rain. Finely crushed egg shells can be sprinkled generously around the base of transplants to discourage transit by slugs or snails (for whom crawling over the fragments is like walking barefoot over gravel for us). Some home orchardists spray a product called Surround, made from a superfine clay, onto their trees to coat leaf and fruit with a thin nontoxic barrier to disease organisms or to feeding by insects like Japanese beetles.

What about purchased beneficials?

Purchased beneficials are a great idea—for the CEO of the company selling them. They are expensive, and they migrate wherever they please after release, not necessarily where we want them to. If our garden ecology is welcoming to helpful insect species, they will come. If it is not, beneficials may give marginal results but will not thrive.

This is not to say that releasing beneficials is always a deadend strategy. It has been shown that release of purchased wasps like Aphidious colmani can be highly effective for aphid control in the more artificial, delicately balanced ecology of a greenhouse. I have used Pediobius wasps for quite effective control of Mexican bean beetle. However, Pediobius is not native to my area, and will not survive the winter as an ongoing population. Since I’ve come up with simpler accommodations with the bean beetles, I no longer go to the expense of bringing in the wasps.

Healthy plants

Our goal is first and foremost to grow healthy plants, using the soil care practices we have discussed. How fortunate that robust, vigorous plants in the peak of health are precisely the ones that best resist predation by herbaceous insects. Every gardener has observed the phenomenon: The plant that was growing vigorously from the beginning thrives despite the presence of insects that feed on it. The plant growing right next to it which for some reason was weak and struggling from the beginning, is devastated by insect feeding.

It has been shown that healthy plants can benefit from some insect predation—the loss to feeding of up to 10 percent of their leaf tissue can actually stimulate growth. Yet another reason why it is foolish to “go ballistic” when we see uninvited insect guests munching on our crop plants.

A Crucial Caveat

It would be an insult to my reader to spin fairy tales. Assisting the maximum burgeoning of insect life possible in our backyard ecology is, I am convinced, the most effective, sustainable, and sane approach to the problem of insect predation in the garden. In the long run it is the only approach that makes any sense. However, that doesn’t mean that it is 100 percent effective—that there will not be some seasons when feeding by some insects results in significant damage to some crops. It is important, therefore, to keep in mind the underlying principles, and the goal of avoiding destructive toxic solutions at all costs—for a more balanced garden ecology in the future, and for pure food on our tables today. We will then persist with our strategy, even when we face insect challenges that might trigger our competitive impulse to win at any cost.

I told the story about my epiphany with Colorado potato beetle, how the surcease of its damage seemed to occur by magic, as soon as I stopped using broad-spectrum rotenone to “fight” it. But other insect competitors have not been this easy. I’ve found Mexican bean beetle and squash bug, as said, much tougher and more resilient. But I have also found ways to accommodate their aggressiveness, and bring in my crops anyway. Cabbage worm is still a bit of a problem, more in some seasons than in others, but the overall trend—for cabbage worm and indeed all my problem insects—is decidedly down, as I plant more and more insect habitats.

With one glaring exception, one spectacular failure of the strategy. I want to tell you about that as well, not only because it’s my duty to be honest with you, but because the tale makes the case all the more strongly that toxic warfare in the garden is always a mistake.

I’ve seen the colorful harlequin bug in my gardens for years. So scarce was its discernible damage, however, in my naïveté I assumed that the harlequin bug was one of those “neutral” insect species that neither boost nor hinder the gardener’s efforts. Then, three years ago, from one season to the next, several of my crucifer crops—especially turnip and radish—were decimated by thronging harlequin bugs. When I say “decimated,” I mean total loss of those crops—zero return on the investment of my time and work. That has been the pattern for three growing seasons now.

There may be many among my readers who part with me at this point: “Rosy visions of ecological balance are great, but I can’t go with hundred percent losses—no way!” But, even with insects at this level of predation, I still am not willing to eat toxic residues on what I’ve worked so hard to harvest as pure food. Even if someone offers an “organically approved” insecticide like rotenone (so approved because it “won’t hurt me”), I still am not willing to undercut the chance for a more balanced, self-correcting mix of insect species in the future. Further, if I did use losses of this severity as an excuse for “going nuclear,” I would never ask these intriguing questions: Why is it that an insect that I once didn’t even recognize as potentially damaging is suddenly, from one season to the next, so devastating? Why is it that Joan and Mike, gardening only a few hundred yards away, are not having the level of harlequin bug predation I am? Why is it that, when I carefully cultivate turnips in my garden, they are destroyed, yet when I simply scattered turnip seed as part of an overseeding mix in the forest garden this spring and walked away—the turnips thrived, yielding fat juicy roots, the only turnips I’ve eaten from my own dirt for three years? Trying to puzzle out answers to these questions means far more to my garden as a functioning natural ecology, and to my own evolution as a gardener, than any amount of “quick relief” I could buy from Monsanto or Cargill.

For readers who remain skeptical, let me assure you that—whatever the nature of insect damage in one crop or another—we harvest from our garden more than we can eat or give away, every season, without fail. If you remember that, it will help you to relax, and be a friend to your garden and the teeming life over, around, and under it.

Pollinators

Thus far we have been focusing on insects that damage crops, and other insects who in their turn keep them from getting too rambunctious. But remember also that large class of insects on whose good work we are deeply dependent: the pollinators. Though their work goes largely unseen, there are few crops that set seeds or fruits without the assistance of these busy little fellow travelers.

Flowering plants—which include the majority of our food crops—go to the considerable effort and resource expenditure to grow flowers and distill nectar in order to form alliances with countless species of insects who will, in exchange for gifts of nectar and shelter, distribute pollen from plant to plant, achieving for immobile plants the miracle of sexual reproduction, with its variability and emergence of new traits after each roll of the genetic dice.

Our nurture of flowering habitat plantings helps nurture the pollinators as well. If you ever doubt that, go sit in them and watch the dozens of species come and go—syrphid flies, butterflies, moths, various beetles, honeybees, and other bee species. If you listen closely enough, you’ll hear them saying Thank you! Thank you!

Honey bees

Of course, all this interest in pollinators may inspire you to start raising them. Keeping hives of honey bees is fascinating and fun; contributes valuable hive products in addition to honey (multi-functional itself for food and fermented beverages, for medicinal use, and as a preservative)—such as royal jelly, pollen, propolis, and beeswax—and ensures heightened pollination of our fruits and vegetables.

We have enjoyed having two hives of bees on our place for two years now. We do not tend the bees ourselves—they are cared for by a friend who pays us a “rent” of five pounds of honey each time he harvests a hive. Keep this sort of arrangement in mind, even if you choose not to keep bees yourself.