The Herbal Insectary (Part Two)

Pink Ladybug Image Copyright Jill Henderson showmeoz.wordpress.com

by Jill Henderson Show Me Oz

In Part One of The Herbal Insectary, I explained what an insectary is and what types of food beneficial insects need and which plants attract and feed them. We also discussed ways to turn beneficial larvae, like black swallow parsley worms, from garden pest into garden ally by providing them a permanent home outside of your main garden. In this installment, I will explain how a dedicated perennial insectary is the best thing you can do for your insect allies and share a few important tips and tricks to make your insectary an even more appealing place for beneficials to call home.

The Perennial Insectary

Most gardeners grow herbs for the same reason they grow a vegetable garden – to reap a healthy and abundant harvest. For many types of herbs, harvest time comes just as, or soon after, blooming begins. Waiting too long to harvest can make the difference between a potent medicinal or perfectly-flavored culinary herb and one that is long past its prime. The conundrum here is that in order to attract beneficials, you’ll want to let your herbs flower. As mentioned in the Herbal Insectary Part One, many beneficials rely on the pollen and nectar that flowering plants provide while also attracting prey for predatory insects like preying mantises, ladybugs, and spiders. For an effective insectary, an abundance of flowering plants and herbs are a must. But you don’t have to sacrifice a quality harvest for their well-being. I’ll explain how in just a moment.

But first, we need to examine another dilemma in the insectary game, which is preventing the larval form of some beneficials, like parsley and dill worms (which are the larvae of swallowtail butterflies), from chowing down your culinary or medicinal herbs before they are ready to harvest. You can try to harvest as much greenery as possible before the caterpillars hatch out and start feeding, but this is not nearly as simple as it sounds. The only option most gardeners ever consider is to destroy the caterpillars before they destroy their crops – even if it means killing off some very beneficial, and beautiful, pollinators at the same time. However, there is another way to handle this conundrum and that is to plant the types of herbs that beneficial caterpillars love to eat in a dedicated insectary outside of your main garden. This way, when you find parsley or dill worms on your garden herbs, you can simply move them over to the parsley, dill, or fennel that you planted in the insectary just for this purpose.

A Place to Call Home

The best thing for you and your beneficials is to grow a hedgerow of herbs and other plants along with a few early and late flowering shrubs and trees such as crape myrtle, lilac, and fruit trees. As a perennial bed, the hedgerow can be mulched deeply to reduce weeding and watering chores. And if you use a mixture of natural mulches like bark, wood chips and deciduous leaves, you will also provide many beneficials with the perfect shelter for hiding and resting during the heat of the day, places for egg laying, and sites for hibernating in winter. Additionally, the relatively undisturbed soil in a perennial insectary is crucial for many beneficials that spend some portion of their life underground, either to hibernate or to metamorphosize into their adult forms.

Praying Mantis egg case on base of wild cherry tree. Image copyright Jill Henderson showmeoz.wordpress.com

At the end of the season when your beneficials are calling it a wrap, ensure they hang around for next summer by providing them with the right environment for hibernation. Whenever possible, avoid removing spent vegetation in the insectary and leave as many large clumps of dried ornamental grasses as possible. Sow cover crops in or nearby the insectary for added protection from harsh winter weather. And when pruning shrubs or trees, be sure to keep an eye out for the foam-like egg cases of praying mantises, which contain next year’s brood. Also, when mowing the lawn for the last time, consider setting the blade just a little higher than normal. Long grass provides ample hiding places and allows beneficial weeds such as dandelion a chance to regenerate faster in early spring. Fall leaves make excellent mulch for garden beds as well as hidey-holes for ground dwelling beneficials and their larvae. If you want to keep the yard tidy, pile up leaves of deciduous trees (but not fruit tree leaves, which should be removed and burned to prevent future leaf diseases), sticks and cut grass into a pile near the insectary, but hidden from view. These piles make great hibernation sites that will double as compost in the future.

Diversity is Key

With so many herbs that fill the requirements of beneficials in terms of food and shelter, you might be tempted to stop there. But wherever time and space allow, go ahead and add in as many flowering plants, shrubs and trees as possible – the more, the merrier! And don’t overlook native species, which increase the overall biodiversity of your insectary. Indeed, one of the most important things you can do to support beneficials is to have a variety of plant species flowering throughout the growing season, particularly early in the spring and late into fall when beneficials need their nectar and pollen most.

Red-spotted purple butterfly drinking from a moist gravel bed. Image copyright Jill Henderson All rights reserved. showmeoz.wordpress.com

One final consideration for the perennial insectary is water, which is crucial for good plant development and the survival of the beneficials living there. Insects don’t need a lot of water, but they do need to have access to it in a form they can use. The easiest way to ensure that insects have available water is to shower or mist plants every day, preferably in the morning. The tiny droplets that catch on leaves and stems make excellent “watering holes” for tiny guests. This works especially well if your sprinklers are set on a daily timer.

If you can’t water every day, consider adding a few butterfly baths around the garden, which all of the beneficials can use. These are easy to make at home. Simply gather a few shallow pie plates or pot saucers and snug them down into to the dirt up to the bottom of the rim. Next, fill them to the very top with coarse sand and gravel and add water until it just glistens on the surface. Beneficials can stand in the sand and suck up the water without danger of drowning. Just be sure to keep the sand moist, especially during the hot, dry summer months. By adding a little drinking water to your insectary, you will make a dramatic difference in the number of beneficials that will call your garden home.

In Part Three of the Herbal Insectary, I’ll talk about how to safely deal with the pests that your good bugs just can’t handle on their own.

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.