If anyone had told me, even ten years ago, that I would be designing my yard to accommodate bugs, I would have called them crazy. Back then any and all bugs were the ENEMY and needed to be immediately eradicated — with powerful insecticides so that death would be almost instantaneous. Today the shelf that used to hold toxic chemicals now holds reference books, a few of my plants are a little “munched” on and my grandchildren play in a safe and healthy environment. All in all, the changes have been good.
Through the years, I have found that relying on beneficials to control pests is more complicated than just sitting back and waiting for the good guys to appear and demolish the bad guys. I have learned that two things are necessary. The first requirement is to eliminate the use of all pesticides, both chemical and organic. Pesticides are non-discriminatory and upset the prey-predator balance. The second is to create an environment that is inviting to predatory and parasitic insects. With ideal conditions, they will remain in the area working, living and reproducing, providing another generation of ecologically sound pest control.
An insectary garden is such an environment. An insectary is a space intentionally planted with an assortment of annuals, perennials, shrubs and trees attractive to a variety of beneficial insects. It supplies food in the forms of both pollen and nectar, gives access to water and provides shelter as well as spots to lay eggs. An insectary typically is planted in layers to accommodate various habitat preferences and has a variety of plants in bloom from early spring throughout the fall.
Although there are no absolutes in terms of size requirements for insectaries, Jessica Walliser in her book Attracting Beneficial Bugs to your Garden recommends a target of just 1% of the total yard area as a beginning goal. The insectary can be designed as just one space, or it can be a series of smaller spaces or even individual plant species incorporated into the overall yard design. Try to keep some of the areas undisturbed; these provide breeding grounds for predators.
Depending on personal preference, insectary gardens and borders can be wild and free areas, or they can be formal and restrained. Either way, allowing a few weeds to remain helps to provide the biodiversity that beneficial insects need.
Location of the insectary is important, however. As much as possible, beds should be located where they can receive six to eight hours of sun each day, as both the plants and the insects benefit from the sunlight. Also, a fairly sheltered location helps those insects that find it hard to fly when it is extremely windy. Finally, closeness to the targeted pests increases the likelihood that the beneficials will not only control their prey, but also remain in the area.
The type of soil preparation an insectary needs varies, depending on the types of plants selected and the existing soil conditions. Those built with native perennials will tend to need fewer amendments since most natives are naturally adapted to a wide variety of soil types. Blooming annuals tend to perform better in a rich, well-drained soil. Regardless of soil type however, all insectary gardens and beds will benefit from periodic additions of compost. The deteriorating plant materials make especially comfortable homes for insects.
Insects are living entities and like all other living things need access to water to survive. In mild, rainy seasons, puddles give adequate water for insects. During hot, dry periods it may be necessary to provide water daily. Including a simple watering hole ensures that the beneficials have a consistent place to drink. Insect watering holes shouldn’t be too deep; bowl shaped rocks work well as do shallow saucers covered with rocks.
Selecting appropriate plants for the insectary is critical to its success. As mentioned earlier, both nectar and pollen must be available from early spring until late fall when insects prepare to overwinter. If a food source is not immediately available when beneficials hatch, then they are likely to move on in to find one and not return. By the same token, beneficials will leave if food sources disappear too early.
One important food source is nectar. Nectar, which is essential for energy, is a combination of water, sugars (primarily glucose, fructose and sucrose), amino acids, certain oils, fats (lipids), proteins and even alkaloids. Because the presence and/or combination of these elements varies from plant species to plant species, the quality and type of nectar also varies from species to species. Having a variety of nectars available gives beneficials the opportunity to consume the best nectar for them.
Where the plant’s nectar is collected is also a factor to consider when choosing plants for an insectary. Not all insects eat in the same way because there is a huge variety of mouthparts in the insect world. Some, such as butterflies and moths, drink nectar by sucking through a straw-like member called a proboscis while others like walking sticks chew in a scissor-like motion. Matching flower shapes, for example tubular versus flat, to the targeted insects’ mouthparts helps assure that the beneficials will be able to access the nectar.
Most people are aware that pollinators and pollination are necessary for plants to produce seeds and fruit. Without pollination, species of plants would disappear. What many are unaware of however is that pollen is a source of protein for many beneficial insects. Without pollen those insects would not be able to reproduce effectively and they would, like the plants, eventually disappear. Numbers of pests would then dramatically increase causing further disruption in the ecosystem.
For the novice, designing an insectary can seem to be a daunting task with too many variables to consider. Luckily, there is a wealth of valuable information available through the various state extension services, published online and from landscape designers committed to maintaining a healthy environment.
Even with insect season in full swing, it isn’t too late to begin inviting the beneficials to your home. Join us next week as we show you just who to invite and what to plant to entice them to stay. See you then!