In the second installation of our Gardening in the Sky blog series, Horticulture Manager Andi Pettis discusses beneficial insects on the High Line.
High Line Gardeners work hard to maintain a balanced garden ecosystem in the park's planting beds, while keeping an eye on plant stresses, pests, and disease. This approach, called Integrated Pest Management (IPM), calls for close monitoring of the park's plants, with a focus on preventative care and ecologically friendly interventions. IPM at the High Line often involves biological pest control methods, meaning living organisms are used to combat pests. Beneficial insects are probably the best known of these organisms, and one of the hardest working "beneficials", as they're called in the gardening world, is the green lacewing.
Chrysoperla rufilabris, the green lacewing, is a diminutive creature, not more than 8 mm long from the tip of its antennae to the ends of its namesake lacy wings, but it is a powerful predator. The lacewing is a generalist; it preys on a wide variety of pest insects, everything from aphids and leafhoppers to mites and psyllids, which makes it a very cost-effective part of our garden pest control strategy. It is actually the larva, not the adult, stage of the insect that is so voracious. Lacewing larva are sometimes known as aphid lions because they can eat between 100 and 600 aphids each before they pupate into adults.
High Line gardeners release green lacewing eggs, approximately 1.7 million of them over the course of the growing season, throughout the mile and a half of the High Line. The eggs come attached to small cards that can be hung near pest populations, ensuring that when the eggs hatch there is a ready source of prey. Once released, the larva go on a feeding frenzy that can last as long as 20 days. Once the larva have consumed enough energy and metamorphosed into adults, they finally mate. The mated females fly to the largest population of prey they can find, where they lay up to 200 eggs each, ensuring that the hatching larva have plenty to eat.
You can encourage lacewing and other beneficial insect populations in your own garden. Plant diverse species that will provide food and habitat for all kinds of insects, and avoid using chemicals to repel or kill pest insects. It may seem counter-intuitive, but by allowing some aphids to live on your plants, lacewings and other beneficial insects will be attracted to the prey in your garden, and are more likely to show up and stick around. Eventually, the predator-prey ratio will balance out, and your beneficial insects will be able to keep pest insect populations manageable.