Gardeners often select flowers because we like them — their color, fragrance, beauty and value. Another twist is to select flowers for their function as an insectary. This nursery for insects is a specific collection of plants known to attract and support helpful insects, such as ladybeetles, to feed on harmful ones, such as aphids.
Insectaries help gardeners with pest control. Beneficial insects we try to attract include ladybugs, lacewings, hoverflies, pirate bugs, parasitic wasps, ground beetles, damsel bugs, tachinid flies, robberflies and garden spiders (although they’re not technically insects). Some beneficial insects also pollinate squash, cucumbers and other crops.
Many insectary plants are common, but the concept is to purposely locate these plants together, where they provide habitat and a succession of blooms so beneficial insects always have food and shelter. It’s a permanent feature encouraging insects to overwinter. A varied plant mix attracts the broadest range of good insects.
Beneficial insects vary in their needs for nectar and protein (from the pollen), as well as how they feed. A mix of plant species offers flowers of different shapes suited to the varying insects’ anatomy. Combining plants that flower in each season assures a steady source of food.
Perennial plants are reliable. However, any that spread aggressively such as mint and common white yarrow are best confined in a planter or large container unless one has the space to let them grow with abandon. Many annuals, such as alyssum, dill, mustard and calendula, will come back from seed each year if the ground is not heavily mulched after their seeds drop.
Areas set aside especially for beneficial insects can be in patches throughout the garden, a border or even long strips.
For more information, revisit the May 2015 and June 2020 Alabama Gardener columns.