The Herbal Insectary

Most gardeners grow herbs for their savory flavors and healing properties, but with a little extra planning the herb garden can become a powerful insectary that attracts thousands of butterflies, beneficial insects and pollinators right where gardeners need them most.

What is an Insectary?

Simply put, an insectary is a place to rear and keep live insects. As a gardener, I can’t think of a better place to rear and keep live insects than in the herb garden, especially when those insects can help you produce more fruit and vegetables by pollinating crops and feasting on destructive insects like cabbage worms, aphids and bean beetles.

Beneficial insects allow gardeners to reduce or eliminate dependence on hard-core chemical and even organic insecticides by wreaking havoc on “bad bugs” that chew holes in leaves, spread viral diseases, disfigure fruits, and weaken or kill plants. Thankfully, the herbs, vegetables and flowers in and around your garden can become part of a natural insectary that supports the life cycles of beneficial insects.

If you garden without toxic chemicals and excessive organic pesticides, you probably already have a few beneficials flitting about your garden. But if you really want to reap the benefits of your insect allies, you will need to learn a little more about them, what they like to eat and where they like to sleep, overwinter, and reproduce. By building an insectary specifically for beneficials, you can support them with everything they need to survive in your garden year-round. And in return for your efforts, your army of good bugs will decimate the bad bugs year after year.

It’s Dinner Time

The first and most important thing you’ll need to do to attract adult beneficials to your garden is to provide them with a quality food source. For that you’ll need to know what they like to eat. For example, praying mantises and spiders are true carnivores and feed primarily on other insects. Adult braconid wasps and hover flies feast on pollen and nectar and prey on other insects primarily to feed their young. Beneficials like ladybugs, which are true omnivores, feast on pollen and nectar early and late in the season when aphids, their preferred food, are in short supply.

The most important thing to remember is that if you provide adult beneficials with the foods they need, they will eventually produce hundreds of larvae, which can be voracious eaters of other insects. In the image below, a pink ladybug feasts on the pollen of a pepper plant in my main garden while awaiting the hatching of newly-laid aphid eggs on my tomato plants. But because these lovely beneficials look very much like cucumber beetles, they are often targeted for destruction by most gardeners. This is just one more reason for growers to get to know both the good and bad bugs in the garden.

Pink Ladybug Image Copyright Jill Henderson showmeoz.wordpress.com

Pink Ladybugs in the Garden https://showmeoz.wordpress.com/2017/06/30/pink-ladybugs-in-the-garden/

Herbs for the Insectary

Of course, when it comes to providing food for your beneficials, herbs just can’t be beat. Not only are they relatively care-free, but many herbs produce small clusters of flowers that beneficials find irresistible. Those that don’t eat pollen or nectar will prey on other insects attracted to the flowers, fruit or vegetation.

In the opening photo, a preying mantis hunts among the flowers of sedum ‘Autumn Joy’ in my insectary, which attracts several species of butterflies, wasps, beetles, hummingbird moths, and spiders, among many other insects. For the squeamish, it can be upsetting to see a mantis munching on a pretty fritillary butterfly. But in order to manage a healthy insectary, we have to understand that nature has a balance of its own that outweighs any perceived loss of the “prettier” or more desirable members of the beneficials tribe.

The following is a partial list of herbs, vegetables and flowering plants in just a few key plant families that provide food, shelter, and hunting grounds for beneficial insects in the garden.

Carrot Family – Apiaceae (formerly Umbelliferae)
Angelica (Angelica archangelica)
Anise (Pimpinella anisum)
Anise Hyssop (Anastache foeniculum)
Caraway (Carum carvi)
Carrot (Daucus carota subsp. sativus)
Celery (Apium graveolens var. dulce)
Chervil (Anthriscus cerefolium)
Cilantro/Coriander (Coriandrum sativum)
Culantro/Mexican Cilantro (Eryngium foetidum)
Cumin (Cuminum cyminum)
Dill (Anethum graveolens)
Fennel (Foeniculum vulgare)
Fenugreek (Trigonella foenum-graecum)
Gotu Kola/Centella (Centella asiatica)
Lovage (Levisticum officinale)
Parsley (Petroselinum crispum)
Parsnip (Pastinaca sativa)
Queen Ann’s Lace (Daucus carota var. carota)
Sweet Cicely (Myrrhis odorata)

Mint Family – Lamiaceae (formerly Labiatae)
Basil (Ocimum basilicum)
Bee Balm (Mondarda didyma)
Bergamot (Monarda fistulosa)
Horsemint (Monarda punctata)
Horehound (Marrubium vulgare)
Catnip/Catmint (Nepeta species)
Hyssop (Hyssopus officinalis)
Korean Mint (Anastache rugosa)
Lavender (Lavandula species)
Lemon Balm (Melissa officinalis)
Monarda (Monarda species)
Marjoram (Origanum majorana)
Mountain Mints (Pycnanthemum species)
Mint (Mentha species)
Oregano (Origanum vulgare)
Penstemon (Penstemon species)
Rosemary (Rosmarinus officinalis)
Sage (Salvia officinalis)
Salvia (Salvia species)
Savory (Satureja species)
Thyme (Thymus species)

Aster Family – Asteraceae (formerly Compositae)
Calendula (Calendula species)
Coneflowers (Echinacea species)
Feverfew (Chrysanthemum parthenium)
Yarrow (Achillea millefolium)
Yellow Coneflower (Ratibida pinnata)

Onion Family – Amaryllidaceae (formerly Lilliaceae)
Bunching Onions, Scallions (Allium fistulosum)
Common Cooking Onions (Allium cepa)
Garlic (Allium sativum)
Garlic Chives (Allium tuberosum)
Leeks and Elephant Garlic (Allium ampeloprasum)
Onion Chives (Allium schoenoprasum)
Potato/Multiplier Onions, Shallots (Allium cepa var. aggregatum)
Walking Onions (Allium cepa var. proliferum)

To any seasoned gardener, one look at this list will assure you that many of the herbs, vegetables and flowers that you already have in your garden are excellent candidates for the herbal insectary. There are quite a few perennial plants in this list are grown in permanent beds outside of the annual vegetable garden. But annual herbs like dill and basil are often sown in the garden right alongside the carrots and beans. But sometimes, having a plant mowed down by the larval form of a beneficial can be frustrating. And this is why you’ll probably want to include a plethora of annual edibles in your insectary alongside your perennial flowers. And with a little thought and observation during the growing season, you will quickly learn which of the annual plants should also be added to a permanent bed outside of the vegetable garden specifically for your army of good bugs.

For example, a heavy infestation of dill and fennel worms can destroy full-grown plants in less than a week, leaving the regenerative gardener with a difficult choice: either destroy the larvae or forgo the harvest. The conundrum here is that if you are forced to destroy these caterpillars, you are also destroying beautiful black swallowtail butterflies that are prolific pollinators and food for other beneficials.

Parsley worm on dill. Image Copyright Jill Henderson showmeoz.wordpress.com The best way around this problem is to plant a plethora of annual herbs and even vegetables that these potential pests love, like dill, fennel and carrots in the insectary – separate from those grown in the garden. This way, you can literally move all the beneficial “pests” you find in the vegetable garden to the same exact kind of plants in the insectary where they can live out their lives as true beneficials. And remember, if you plant extra plants in a perennial insectary specifically for beneficial pollinators like these, you will also see an increase in beneficial insect-eating adults like spiders, wasps and praying mantises in your garden.

In the next installment of this series, I’ll discuss how to develop a perennial insectary in your yard complete with food, water, and shelter so your beneficials can make themselves at home year-round.

Until then, happy gardening!

THPOKH-214x32115 Learn more about growing herbs in my book:
The Healing Power of Kitchen Herbs

The Healing Power of Kitchen Herbs is a no-nonsense guide jam-packed with no-nonsense information on growing, harvesting and using 35 of the world’s safest and most flavorful herbs. In addition to the 35 detailed herbal monographs are entire chapters on growing, harvesting and using kitchen herbs to spice up your favorite dish or create healing herbal remedies. This is one book you will turn to time and time again!

Available in the Show Me Oz Bookstore

Jill Henderson is an artist, author, and the editor of Show Me Oz . Her books, The Healing Power of Kitchen Herbs, The Garden Seed Saving Guide and A Journey of Seasons can be found in the Show Me Oz Bookstore. Jill’s work has also appeared in The Permaculture Activist, The Essential Herbal, Acres USA, and Llewellyn’s Herbal Almanac.