My toddler son likes to sit in the patch of flowers next to our front stoop, a perfect vantage point for watching insects zoom over his head.
Throughout the summer, as I watched him play in the garden, I also watched the garden. Among the many wildflowers, I noticed that several red aphids had found the brown-eyed Susans, and a few bright orange aphids had discovered the butterfly milkweed.
It wasn’t very long before those few aphids became many, and soon the plants began to droop as the aphids fed on them. But within a few days, I began to see other insects among the aphids, namely lady beetles (aka ladybugs), lacewings and small wasps, beneficial insects that can limit outbreaks of pests like aphids.
The tiny wasps I saw around the aphids were parasitoid wasps, insects that lay their eggs on or inside insect hosts. The young wasps fed off the aphids, ultimately killing them when they emerge as fully developed adults.
These and other predator and parasitoid insects play a major role in reducing pest damage by suppressing insect pests. In fact, native species of predators and parasitoids contribute at least $4.5 billion annually to crop pest control in the United States.
In order for predators and parasitoids to contribute to pest control, they need habitat. Many require floral nectar or pollen to complete their life cycle or see them through times when prey is scarce. Less disturbed habitat within or close to a garden or crop can provide these resources, as well as shelter, alternative prey and a refuge from pesticides. Recognizing the value of predators and parasitoids to their bottom line, some farmers include native wildflowers in their field borders or set aside strips of native bunch grasses to serve as habitat refuges.
Conversely, yards with large expanses of manicured lawns and only a few types of ornamental shrubs provide neither food nor shelter for predators and parasitoids (or other wildlife). Outbreaks of bagworms, lacebugs or other common pests that cause unsightly defoliation of ornamental shrubs and trees often occur in these simplified landscapes. Flowers are already a valued component of gardens and yards. When selected and planted in yards, native wildflowers provide habitat for beneficial insects that can limit pests like bagworms and reduce or eliminate the need for pesticide applications.
This habitat can also support other beneficial insects such as pollinators. Pollinators are responsible for the reproduction of nearly 85 percent of flowering plants around the world, allowing plants that are food or habitat for other wildlife to persist. Pollinators can also be a food source themselves for other wildlife, like songbirds. They are an indispensable component of a healthy environment.
Pollinators are vitally important to agriculture, too. More than two-thirds of crops that produce fruits, vegetables, spices, nuts, seeds and livestock forage depend on them.
There are simple steps that everyone can take to conserve beneficial insects, including creating flower-rich gardens, restoring natural areas, and protecting beneficial insects and their habitat from pesticides. To learn more, visit the Xerces Society for Invertebrate Conservation website, www.xerces.org. The Xerces Society works to protect these small animals that sustain our lives and our ecosystems.
In my own home garden, once the predators and parasitoids moved in, the numbers of aphids dwindled, and the plants rebounded. My garden’s flowers provide food for pollinators and other beneficial insects, as well as an endless source of interest for my family.