Intro to Farmscaping: Insectary, Trap & Repellent Crops for Pest Management
A Hensley's Seed Co. guide
Farmscaping takes a whole-farm approach to controlling pests biologically. It relies on cultural practices such as insectary plantings, trap crops and cover crops that support beneficial insects and discourage pests. The aims are to keep pest numbers below damaging levels, cut back or eliminate chemical insecticides, and raise yields.
What Are Beneficial Insects?
Beneficial insects are natural enemies of crop pests, a kind of living pest control. You can buy beneficials to release, but this guide focuses on attracting and keeping the ones already living near you. Plenty are close by and ready to work.
Helpful insects come from many groups and habitats, including lady beetles, big-eyed bugs, spined soldier bugs, assassin bugs, minute pirate bugs, ground beetles, soldier beetles, hover flies, green lacewings and predatory wasps, plus spiders. Parasitoids, such as parasitic flies and wasps, and beneficial nematodes matter too.
Lady beetles prey on aphids and other soft-bodied pests. Photo: University of Maine Pollination Security Project
Beneficials fall into two broad groups:
- Predators: bigger, generalist hunters that usually eat insects as larvae, adults or both. They're larger and slower and eat a wide range of prey, sometimes even each other when their favorite food runs short.
- Parasitoids: tiny specialists, mostly wasps or flies, that attack particular life stages of their hosts, like eggs and larvae, and seldom adults. Because they're so small, parasitoids are hard to spot in the field, and their impact may only become clear after they've moved on. They're very effective against often quite specific pests and are very sensitive to habitat changes and pesticide sprays.
Braconid wasps are key parasitoids of tobacco and tomato hornworms. Photo: R.J. Reynolds Tobacco Company, Bugwood.org
Some examples…
- A single lady beetle larva can eat hundreds of aphids before it pupates.
- The braconid wasp Cotesia congregateslays its eggs inside living tobacco and tomato hornworms. The larvae hatch and feed on the caterpillar's body fluids, then chew their way out and spin cocoons on its back, and the hornworm eventually dies.
- Ground beetles in the family Carabidae eat weed seeds and can noticeably reduce weed pressure the following season. They also hunt many pests opportunistically, including aphids, cutworms, armyworms and cucumber beetles.
Ground beetles eat large numbers of weed seeds. Photo: Eric Gallandt, PhD, weed ecologist, University of Maine
Birds, bats, reptiles and other vertebrates can help too in the right setting. Growers have many potential allies against pests.
Why use beneficials?
Relying on beneficial insects makes a farm more environmentally sustainable by controlling pests without chemicals. It can also save real money, and workers benefit from less chemical exposure.
Attracting Beneficials and Discouraging Pests
A sound farmscape plan combines tactics that draw in beneficials with tactics that hold back pests. For instance:
- Habitat modification: growing plants that give beneficial insects shelter, nectar and alternative prey. These insectary plants attract beneficials, keep them around and help their numbers grow.
- Cultural Practices: that disrupt, deter, repel or trap pests, like crop rotation and well-targeted sprays, help break pest life cycles and protect local beneficials. Repellent plants can also discourage pests, and trap crops lure pests away from the cash crop by playing on their food preferences.
Below we'll cover each piece, with examples from a trial farm that put these ideas into practice.
Getting Started
It often helps to begin with one crop that's under heavy pest pressure. One farm started with its cucurbits, which were being hit hard by cucumber beetles, squash bugs and green peach aphids that were also spreading disease through the planting.
Start with these questions:
- Which crop needs protection?
- Which pests are the main problem on that crop?
- Which beneficials attack those pests?
- How can you attract those beneficials?
Answering them takes some homework. Useful resources include:
- ATTRA trap cropping resources
- UMass Amherst scouting resources
- Ecological engineering approaches to pest management
- Cornell IPM guides
Implementation on a research farm
That farm built several pieces into its plan: insectary plantings, trap crops, repellent plants and skip lanes (unplanted, mulched rows). It also changed how it used organic insecticides, spraying the trap crop only when pests reached a set threshold instead of on a calendar schedule, and it covered the cash crop with row cover.
Insectary Plants, Trap Crops, & Repellent Crops
Insectary Plants
Beneficial insects need food and shelter, and an insectary planting makes them much more likely to stay and help control pests.
"Bug Blend"
The insectary mix on that farm combined crops with long, overlapping bloom periods, including oats, Buckwheat, Phacelia, Alyssum, Dill, Cilantro, Crimson Clover, Medium Red Clover, Berseem Clover, and Ammi.
A mix of insectary plants serves local insects in many ways. Buckwheat is especially valuable because it blooms for a long time. Grasses and grains shelter ground beetles and spiders and give other beneficials shady spots to lay eggs. Members of the Apiaceae, the carrot family, such as cilantro, dill and ammi, bear umbels of tiny fragrant flowers rich in nectar.
Trap Crops
Trap crops draw pests away from cash crops by taking advantage of what they prefer to eat: the pest finds the tastier trap crop and leaves the cash crop alone. In the cucurbit example, the farm planted Hubbard squash around the field edges and green zucchini at the row ends. Ideally the trap crop reduces or removes the need to spray the cash crop, and the trap crop itself is sprayed only if pests on it reach a set level. For action thresholds, see the New England Vegetable Management Guide or Cornell’s crop specific IPM guides.
Repellent Crops
Plantings of nasturtium and marigold were used to help keep pests off the cash crops.
Skip Lanes
Skip lanes (unplanted, mulched rows) also buffered the cash crop and slowed pest movement.
Results on a research farm
Hover fly larvae devour aphids, and adults feed on nectar.
In the first seasons with these practices on several acres of cucurbits, the farm reported:
- The area treated with pesticide dropped dramatically
- Spending on insecticide sprays fell to nearly nothing
Large populations of hover flies and many kinds of lady beetles, plenty of minute pirate bugs, and signs of parasitized squash bugs.
Parasitized squash bugs. The white eggs on their backs are probably from Trichopoda pennipes, a parasitic tachinid fly. Photo: Whitney Cranshaw, Colorado State University, Bugwood.org
Lessons
Lessons from research and on-farm experience:
- Choose plants with a purpose rather than at random. An insectary mix has to feed and shelter your target beneficials in the right amounts at the right time, and a trap crop has to appeal strongly enough to your target pest. Research the plants that best match your needs.
- Think about how these plantings will affect field preparation. Plan ahead for how a farmscape will change your overall farm operations.
- Collect data deliberately. A great place to start is the UMass Amherst scouting resources.
5 Steps to Establishing an Insectary
These steps are adapted from a University of Maine Cooperative Extension fact sheet on establishing pollinator and beneficial insect plantings.
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Minimize Weed Pressure
Controlling weeds, and especially the weed seed bank, comes first. A well-prepared bed sown with a perennial flowering mix can feed beneficials for 5–10 years, but only if weeds are kept down. Weeds left uncontrolled before planting will quickly overrun slow-growing perennial flowers, often in the first year.
To shrink the weed seed bank, growers can use stale seedbeds, flame weeding, soil solarization, topsoil removal, cover crops combined with stale seedbeds, or, if needed, careful repeated herbicide use. Even two or three stale-seedbed cycles in spring before sowing can cut weed competition a lot and help the planting last longer. Read our article on weed management basics for more.
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Prep the Soil
Get a soil test, available through your land-grant university, and follow its recommendations. Light, shallow tillage before sowing loosens the surface and improves germination and emergence.
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Sow the Seed
Native seed drills, hydroseeders and spin seeders such as the Ev-n-Spred® all work well for sowing beneficial insect mixes. Unless the area is very large, a hand-cranked spin seeder is a practical way to sow plantings of up to several acres.
Mix very fine seed, such as wildflower seed, with sand, vermiculite or similar filler so it spreads evenly. Rake lightly with a landscape rake after sowing.
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Ensure Seed-to-Soil Contact
Small annual and perennial seeds, wildflowers especially, need firm contact with soil to sprout and establish, so pressing the seedbed after sowing is essential. Cultipackers and lawn rollers both do this well.
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Maintain: Irrigate the 1st Year & Mow Once Per Year in Late Fall
Once established, these plantings need little care. In the first year, though, watering ¼–1" per week helps slow-growing perennials take hold. Mow the planting once a year in late fall after the last flowers fade.
Small but Mighty
Beneficial insects work in countless, intricate ways that matter not only to farming but to the whole web of life. Most of the world's leading food crops benefit to some degree from insects, through pollination, pressure on pests and many other ecosystem services. Without them, our lives and diets would be far poorer. A resourceful grower gives them a safe home and puts their small but mighty skills to work.
