How to Use Trap Crops to Deter Pests

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Examples of best trap crops

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One way to protect your plants from insect attacks is to use trap crops. What are trap crops? We’ll explain how they work, give examples of trap crops (such as nasturtium, marigolds, and dill), and tell you which beetles and other insect pests they control.

What is a Trap Crop?

Basically, a trap crop consists of sacrificial plants that draw the harmful bugs away from the plants you want to keep bug-free.

They act as a decoy, so you won’t be tempted to use chemical pesticides. A lesser-known component of companion planting, this is an organic technique market gardeners have used for years in their integrated pest management (IPM) programs.

The insect pests find certain trap crops even more attractive than the plant you are trying to protect.

 Tomato hornworms can defoliate a plant almost overnight and eat chunks out of your green tomatoes as well.

Examples of Best Trap Crops

  • Dill for Tomato Hornworms: Since the moth that lays hornworm eggs is also attracted to dill, plant some nearby and it will deposit its eggs there. When the larva hatch they will happily munch on the dill instead of your tomatoes. Learn about about controlling tomato hornworms.
To avoid aphid damage like this on your precious roses try planting nasturtiums nearby.
  • Nasturtium or Okra for Aphids: We’re all familiar with little green (or white) aphids. They find their way into most any garden and suck the liquid out of plant leaves. Nasturtium are valuable plants as traps for the aphids which will likely go for these plants before your prized
    tomatoes. Okra is also a trap crop for aphids; Interplant amidst tomatoes to minimize this problem. Learn more about aphid control.  
  • Radishes for Flea Beetles: Flea beetles can make your brassicas look like they have been hit with buckshot. Radishes are also in the brassica family, so they will be attracted to them instead if you plant some sacrificial radishes around the bed. Nasturtiums are a favorite trap for flea beetles, too.
I know where to look for the Japanese beetles. They do some damage to the soybean leaves but we still get plenty of beans for edamame.
  • Soybeans, Scented Geraniums, Four-O’Clocks Flowers, and Zinnia for Japanese Beetles: These iridescent beetles adore roses (and many other plants). However, these actually like four-o’clock flowers and zinnia even better! This is why many gardeners interplant or ring their roses with these annuals. Once the Japanese Beetles are covering the flower, uproot it and put the entire plant in soapy water. After several days, problem solved.

    Japanese beetles are also attracted to scented geraniums. In fact, the flowers are toxic to the beetles!   Learn more about Japanese Beetle control.
  • Sorghum for Sweet Corn: Something eating your corn? Those are the destructive corn ear worms. Try planting sorghum nearby to draw them away.
Cabbage worms can defoliate your brassicas quite quickly and are yucky to find in your broccoli!
  • Cabbage Moths for Collards: Those pretty white “butterflies” in your garden are a major pest. Cabbage moths can be kept busy with a patch of collards planted far away from your broccoli and cabbage. Nasturtium leaves may attract them, too.
  • Parsley for  Slugs: As slugs are partial to tender leaves, they’re big fans of left lettuce. Plant parsley or chervil on the edge of the vegetable garden, perhaps another plant after that, and put your lettuce in the very center. Or give parsley its own plot about 10 feet away to give slugs their own buffet! Find more slug control tips.
Monitor your sacrificial squash plants regularly and dispatch any squash bugs you find there.
  • Millet for Squash Bugs: The bane of many gardeners, squash bugs can be trapped by planting millet between the plants. To cut down the population, check the plants in the morning and knock off the offenders into a bucket of soapy water to keep them from laying more eggs. Learn more about squash bug control.
Too many cucumber beetles will eventually ruin your cucumber patch!
  • Cucumber Beetles are similarly attracted to another grain plant—amaranth. This lovely plant can really send off beetles that show up in late summer and fall.
Squash vine borer moth is not often seen at rest. Spotted this one in the soybeans on a rainy morning.
  • Cucumber beetles, squash vine borers, and squash bugs will be attracted to Blue Hubbard squash plants. Farmers grow them outside the perimeter of the squash patch, getting them into the ground at least two weeks before they plant the main crop of squashes so they are bigger and more attractive. They have found that just 6 or 8 Hubbards planted 3 to 8 feet away from the main crop will sufficiently protect 100 squash plants. Remove the bugs as soon as they are spotted.
Leaf-footed bug populations can get out of control quickly.
  • Sunflowers for Stinkbugs and Leaf-footed Bugs: Sunflower is such a huge lure for stink bugs that it is used as a trap plant in commercial crops. But if you don’t want to sacrifice your sunflowers, they also love vetch, millet, sorghum, and okra. All these plants are great for the soil as well!
  • Marigolds for Earwigs: Marigolds are known for killing nematodes (a root-borne pest that eats tomatoes), but they also lure earwigs away from chard and spinach.
Nasturtiums are a great trap crop, drawing several types of insects away from your vegetables.

How to Plant Trap Crops

Timing is important. Trap crops need to be up and growing before the offending insects usually appear. Larger plants will be more attractive to them and better able to survive the onslaught. 

Trap crops can be planted as borders around the perimeter of the garden, intercropped in alternating rows with your plants, or mixed randomly within the beds. Always plant extra trap plants if you have to pull one or two.

Only plant trap crops for serious pest issues.  Growing a trap crop can draw even more pests to your garden, so only use this strategy if you have an ongoing problem with a certain insect. For example, if you’ve had trouble growing one crop year after year due to pests, then think about a trap crop. Be sure to check the trap crops often and remove any bugs. If the infestation is severe, remove whole leaves or even the entire plant!

If you are growing a farm or large garden, trap crops will certainly save you money since a packet of flower seeds costs little, but your crops are valuable. Plus, you’ll save quite a lot on pest spraying and avoid reliance on pesticides if you value a chemical-free garden.

Trap cropping is not a magic bullet. Consider it another weapon in your arsenal to use against problem pests!

Learn more about companion planting and which plants should be paired together to prevent pest problems.

About The Author

Robin Sweetser

Robin has been a contributor to The Old Farmer’s Almanac and the All-Seasons Garden Guide for many years. Read More from Robin Sweetser

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