Attract Beneficial Insects for Natural Pest Control

1 / 10
Designing an insectary border that is appealing to both beneficial insects and humans isn’t as difficult as it might seem.
2 / 10
Intentional beneficial insect releases are one element of biocontrol: the practice of using one living organism to help control the population of another.
3 / 10
It is important to create a structurally diverse environment capable of supporting insects of all sorts – all while keeping your own sense of aesthetics in place.
4 / 10
Incorporating individual beneficial insect–friendly plants into an existing landscape is a good way to get started.
5 / 10
Select the location of your insectary border carefully, as many of the most desirable plants prefer six to eight hours of full sun per day. A slightly sheltered site is ideal for smaller beneficials that have difficulty flying in windy conditions.
6 / 10
Covering just 1 percent of your property with insectary plantings is a good initial target. And because many insectary plants are very attractive, using them as part of a foundation planting adds color, texture, and complexity to what is often an uninteresting part of the landscape.
7 / 10
An insectary planting like this one is intentionally created to provide for the environmental and nutritional needs of a vast array of natural enemies.
8 / 10
A diversity of flower shapes and bloom times is critical for enhancing both the aesthetic appeal of the garden and its ability to support a broad range of natural enemies.
9 / 10
Look to include appealing color combinations in your border but also keep varied floral structures in mind. This combination of oregano, asters, and laceflower partners small, tubular flowers with daisylike flowers and tiny, shallow umbels.
10 / 10
In “Attracting Beneficial Bugs for Your Garden,” organic gardening expert Jessica Walliser provides an accessible guide to selecting, placing, and caring for plants that will invite beneficial insects into your garden to do the dirty work of pest control for you.

It may seem counterintuitive to attract insects to your garden; but with the right knowledge and a good plan, you can attract beneficial pollinators and predators that will eat the pests feeding on your organic fruits and vegetables. Jessica Walliser is a subject-matter expert, and her book Attracting Beneficial Bugs to Your Garden (Timber Press, 2014), explains exactly how to plant insectary borders in and around your garden.The following is an excerpt from, “Your Beneficial Border.”

A Guide to Designing for the Bugs

As you already know, many natural enemies feed not only on other insects but also on nectar and pollen. Insectary plantings, or insectary borders, are areas intentionally created to support the nutritional and environmental needs of insect predators and parasitoids. These areas can come about simply by letting part of the yard or farm go wild, but often they are purposefully created. They are designed and maintained specifically to cater to the needs of beneficial insects.

The design of the border greatly influences the types of predators and parasitoids lured to it, as well as the length of their stay and even their health and well-being. Several factors are involved in such consequences, including the diversity of flower shapes and bloom times, the complexity of plant architectures, and the creation of winter habitat. Blending all these factors together with some sense of aesthetic appeal can prove challenging. This excerpt shows you how to do it.

Here you will learn how to use all the plants profiled in Attracting Beneficial Bugs to Your Garden, and some others as well, to develop a diverse environment that encourages beneficial insects of all sorts. Just so you won’t be intimidated by the design process, I provide a handful of insectary border plans for you to use as a guide. You can take the ideas presented here and adapt them to your own landscape based on your aesthetic sense, your gardening climate, and the size of your backyard.

Biocontrol Tactics for Your Yard

I once had a discussion with an insect-loathing friend (yes, I do have a few of those) about our food future. After I mentioned the decline in European honeybee numbers and its effect on crop production, she said, “Well, I guess we just won’t have any more honey.” I then began a gentle rant about how the missing honey will be the least of our problems if we don’t work on preserving pollinators of all sorts. Pollination is essential to human life in so many ways. She then told me she firmly believes that someday all the world’s food will come from high-rise hydroponic farms and that we’ll probably just invent some kind of robotic pollination system, so we can surely survive without bugs of any sort.

I wanted to laugh out loud, but instead I mentioned what I like to call the poop factor. Who is going to get rid of all the waste in the world if there aren’t any insects? Then I mentioned the food chain factor: insects are undeniably responsible for nearly all the food we eat, even the animals (are they to be grown in high-rise laboratories, too?). And then, of course, there’s the whole air-we-breathe factor, which she clearly had not considered at all. My reply was something like, “If we don’t have bugs, we don’t have plants of any sort, and if we don’t have plants, bye-bye oxygen. No oxygen, no humans.” Don’t get me wrong–I love a good debate. But there’s no debate here. We need bugs.

But we’ve also got some problems with them that will probably never be sorted out. As you already know, fewer than 1 percent of insects are considered agricultural pests, but those that are present some big challenges. As we continue to turn to more ecologically friendly methods of pest control, the use of natural enemies to aid our efforts becomes more and more valuable. The science of biological control, or biocontrol, uses one living organism to help control the population of another. After implementing the ideas presented in Attracting Beneficial Bugs to Your Garden, you’ll be practicing a few different biocontrol tactics in your own yard.

The first is conservation biological control. This refers to protecting and promoting the natural enemies already existing in your landscape by reducing or eliminating pesticides and by creating a more favorable habitat. Conservation biological control through habitat modification is essentially the act of building a landscape to enhance the numbers and actions of natural enemies. It is also possible to practice biocontrol through intentional insect releases (often referred to as augmentation), though unless you are releasing the insects into a contained environment, this type of biocontrol is only temporary. The intentional importation of natural enemies is a practice I’ll discuss in a later chapter.

Another type of biological control, known as classic biocontrol, is not practiced by farmers or gardeners but rather by governmental agencies and universities. It refers to the intentional introduction of an insect predator or parasitoid to combat a particular pest. Classic biocontrol techniques are meant to be self-sustaining and permanent. (Remember what Joseph Patt told us about the parasitic wasp from Asia being considered for release in the United States to control the Asian citrus psyllid? That’s an example of classic biocontrol.)

Though the term biocontrol might sound like something a terrorist is involved in, I can assure you that it is, in fact, a very useful (and definitely under appreciated) tool for gardeners and farmers. Since the importance of doing away with pesticides is discussed earlier in the book, this excerpt focuses on how to enhance your landscape to the benefit of insect predators and parasitoids.

Planning Your Border

The ability of a particular insectary planting to support beneficials is dependent on many factors, including its location, size, and design. Let’s consider each of these in turn.

Location

Begin the process of designing your own insectary border by carefully considering the placement of the planting. Border location is important because some natural enemies, like hoverflies, larger parasitic wasps, tachinid flies, and robber flies, are capable of traveling great distances, while others, including ladybugs, ground and rove beetles, smaller parasitic wasps, and the larvae of many predators, are more likely to have a far smaller home range. There are two ways you can approach the creation of your border.

The first is to not consider it a dedicated border per se but rather to incorporate as many of the plants profiled in the previous chapter into your existing landscape as possible. Scattering them about in hopes of increasing the structural and floral diversity of your existing landscape will likely lead to an increase in the numbers and diversity of beneficials you find on your property. To some extent, this is how I got started with my own insectary plantings. I already had a handful of perennial gardens, a vegetable garden, and lots of shrub beds and foundation plantings. Instead of adding plants that I thought were pretty, I began to incorporate some of the species known to provide for beneficials (many of which also happen to be very pretty plants). The addition of any of these plants to any part of your landscape is a decent place to start.

The second way to approach the creation of your insectary border is to do what I eventually did: purposefully design and install a proper insectary border. The placement of such a garden is only slightly trickier than the willy-nilly approach of individual plant additions. Wind and sun exposure should be a consideration here, as many of the appropriate plants require at least six to eight hours of full sun per day (not to mention that most good bugs also do their best work in full sun), and many smaller species of beneficials have difficulty flying in windy conditions and thus prefer a somewhat sheltered site.

Another factor influencing the placement of your border is its proximity to other garden areas. For example, if you are looking to increase the predation and parasitism rates of the pests in your veggie garden, consider locating your border in close proximity to it. Molecular gut-content analysis found phacelia pollen in the digestive systems of hoverflies as far as 200 meters (656 feet) from the plants themselves. That’s a substantial distance. But just because we know that some predators and parasitoids are capable of traveling sizable distances, why force them to? Why risk their not returning to the veggie garden for prey after they visit the nectar-rich insectary border?

The closer a dedicated insectary border is to the targeted pests, the better. That being said, close is relative. If your yard is a quarter-acre lot, anyplace is a good place to locate an insectary border in terms of its proximity to pests; but if you have a larger property, think a bit more carefully about its placement.

Size and style

The size of your insectary border matters, too, though not as much as you might think. Yes, the area should be proportionate to the remainder of your landscape (if only for the sake of good design), but there’s really no need to overthink the garden’s size in regard to its benefits to natural enemies. Covering just 1 percent of a given home landscape area with insectary plantings is a good initial target.

The targeted 1 percent can come in the form of a single insectary border positioned judiciously, or it can be the result of several smaller insectary beds dotted here and there, perhaps in relation to pest-prone areas. For a 1-acre lot, this translates to a single 20-by-20-foot (6-by-6-meter) border, or a similarly sized 400-square-foot (37-square-meter) area. For a quarter-acre lot, a single 10-by-10-foot (3-by-3-meter) border, or a similarly sized 200-square-foot (18.5-square-meter) area would suffice. While this may seem a rather large area to plant and maintain, don’t forget that included in the desired 1 percent are also any areas that already contain insect-friendly plants. This means that if insectary plants are incorporated somehow into the rest of your landscape, the size of your dedicated insectary border can be reduced by an equal amount. Keep in mind, though, that there are no rules about all this–only the suggested objective of doing whatever you can to increase the habitat available for natural enemies.

Depending on your garden style, an insectary border can be formally constructed, crisply edged, and precisely designed; or it can be a casual blend with no formal design, minimal maintenance, and riotous color. Fitting the overall design of an insectary border into the scope and attitude of your existing landscape style is a must. Otherwise, it will appear to be plunked there–an afterthought of sorts.

Design

Once you’ve decided on the site, size, and style of your border, begin making a few casual drawings of the anticipated bed in reference to the existing landscape and the structures already on your property. Keep things to scale if possible (large graph paper might help).

First draw the outline of the house, garage, shed, pool, and any other structures. You don’t have to be a perfectionist by any means, but getting a rough idea of existing curves and angles is helpful. Then draw in any existing gardens, beds, and borders. Examine their edges and aim to create your new insectary border with a complementary framework. If your landscape has lots of soft curves, edge your insectary border with one too. If sharp, angular corners abound, then stick with them and build a more rectangular insectary border. Experiment on the paper with different bed shapes, sizes, and angles. Invest in a good eraser–you might need it.

After settling on the basic geometrical design of the border, turn to plant selection. Sort through the plant profiles in the previous chapter, making note of which are appropriate for your hardiness zone, which are must-haves, and which are I-think-nots. Once you’ve compiled a list of desired plants, categorize them based on bloom time. Without a doubt, the central and most critical focus of plant selection here is staggered bloom times.

From the moment many natural enemies emerge from their winter rest, they need to begin to feed. Without early nectar sources present, the insects commute to find suitable forage and might not return to your landscape (especially if it is a species capable of distance travel). Nectar, pollen, and prey need to be available throughout the entire season and right up to the point where overwintering insects enter diapause. In warmer climes, this means organizing the garden so that several different insectary plants are flowering year-round.

Both flower and plant structure are significant here as well. Vary the bed’s architectural matrix by introducing plants of differing heights, girths, and frames. The diversity factor comes into play big time here. Don’t settle for only members of the same plant family with similar floral architecture. Incorporate a mixture of shallow, tubular flowers with daisylike ray flowers and tiny, delicate umbels. Look to flower and foliage color, too, as the combinations should be suited to your taste, but the objective of diversity needs to take the lead.

Use your on-paper design to fiddle with different plant layout scenarios if you’d like, though this is not a step I usually do myself. Since I have trouble envisioning a three-dimensional garden via a two-dimensional plan, I like to work within the bed itself. However, I do use the written plan to determine the approximate number of plants I’ll need to adequately fill the space (this is where the mature plant size measurements I provide in the plant profiles come in handy). Suitable plant spacing is necessary not only for the health of the plants but also to facilitate insect movement. Place the plants too close and they outcompete each other; place them too far apart and smaller natural enemies may have a hard time scooting from plant to plant to find suitable food and prey.

Once I determine the number and types of plants I want to include, I buy them and then head to the garden to determine their placement. I place the plants, pot and all, and then move them around as I see fit. In my mind, I visualize their mature size, flower structure, and color at maturity, and work to pair them with neighboring plants in a way that appeals to both my own sense of aesthetics and the needs of all my beneficial bugs. The good news is that if I don’t like something down the line, it’s easy enough to change simply by shuffling things around.

Insectary Garden Plans

Planning your border may be easier for you if you have some models to follow, so I provide four different insectary garden designs in my book. Within each design are all the desired elements–staggered bloom times, diverse floral and plant architecture, and visual appeal. All the plans are also easily size-adaptable–you’ll note that they lack dimensions. That’s so that you can shrink or expand the bed according to the amount of space you have available simply by adjusting the number of plants to locate in each position. Bigger areas will allow for three or four of some of the plants noted on the plan, while smaller spaces may have room for only one specimen. There is also quite a bit of wiggle room regarding flower color and cultivar selections. I purposely left out cultivar names so that you can choose them based on what is most attractive to you in regard to color combinations and growth habits.


Taken from Attracting Beneficial Bugs To Your Garden © Copyright 2014 by Jessica Walliser. Published by Timber Press, Portland, OR. Used by permission of the publisher. All rights reserved.