Green lacewings (family Chrysopidae) are highly valued insects that serve as powerful biological control agents against common garden pests. Understanding the needs of the adult lacewing population is the direct path to encouraging their reproduction and subsequent pest control benefits. Attracting and retaining them requires a holistic approach focused on consistent food sources, suitable shelter, and a safe environment.
Understanding the Green Lacewing Life Cycle
Adult green lacewings are slender, about one-half to three-quarters of an inch long, with bright green bodies and four translucent, intricately veined wings. They feature long antennae and distinct, often iridescent, copper or golden eyes. The female lays between 100 and 300 eggs during her lifespan, each suspended individually on a slender, hair-like stalk.
This unique egg placement prevents the newly hatched larvae from immediately eating their siblings. The larvae, which hatch after only a few days, are the true powerhouses of pest control. They resemble tiny, mottled alligators, equipped with large, sickle-shaped mandibles used to impale and consume prey.
The larval stage is often referred to as the “aphid lion” due to its ferocious appetite, capable of consuming over 200 soft-bodied pests per week. After developing through three instars, the larva spins a silk cocoon to pupate, completing the four-stage cycle before emerging as an adult. Attracting the adults ensures a reliable, continuous supply of these predatory larvae throughout the growing season.
Providing Essential Adult Food Sources
Attracting adult lacewings relies on meeting their specific nutritional requirements, which differ significantly from their carnivorous young. Adults primarily feed on plant nectar, pollen, and honeydew, the sugary substance secreted by pests like aphids. Small, clustered flowers are most effective, as these structures allow easy access to nectar for insects with shorter mouthparts.
Specific plant choices include members of the Umbelliferae family, such as dill, fennel, and angelica. Other recommended options are cosmos, yarrow, and sweet alyssum, which offer accessible pollen and nectar. Planting a diverse selection ensures a food source is consistently available throughout the season, promoting prolonged reproduction.
This non-predatory diet sustains the adult population, allowing them to remain and reproduce where pest prey is present for their young. Maintaining a steady supply of floral resources encourages females to lay their stalked eggs nearby, ensuring larvae hatch directly into a food-rich environment. In the absence of floral resources, adults will feed on honeydew, which helps clean up the sticky residue left by aphid populations.
Designing Habitat and Shelter
Retention of the lacewing population depends on providing adequate physical habitat beyond food plants. Diverse plant foliage and structures are necessary to provide surfaces for females to lay their distinctive eggs. Layers of different heights, including shrubs, trees, and ground cover, offer protection from wind and larger predators.
The physical environment must also account for periods when lacewings are not actively flying or feeding. Depending on the species and climate, lacewings overwinter as either an inactive adult or as a pupa within its silk cocoon. They seek out protected, undisturbed spots to survive the cold months.
Leaving areas of the garden untidy provides necessary shelter, which is a key management practice for retention. Overwintering sites often include:
- Undisturbed leaf litter.
- Brush piles.
- Tall grasses.
- Under loose bark.
Allowing some sections of the garden to remain less manicured ensures lacewings have a safe space to emerge in the spring, ready to begin the life cycle anew.
Practices That Deter Lacewings
The most significant factor that drives lacewings away or destroys established populations is the use of broad-spectrum chemical treatments. Insecticides and miticides kill lacewing larvae and adults indiscriminately, negating any benefits gained from attracting them. Avoiding chemical applications is the most effective way to maintain a healthy population.
Similarly, overly tidy gardening actively works against lacewing retention. Aggressively removing all fallen leaves, dead plant material, and debris eliminates the essential overwintering habitat where adults and pupae survive the colder months. A clean garden removes the structures needed for the population to return each spring.
It is also important to tolerate a low level of pest activity in the garden, particularly aphids. Maintaining a small, manageable population ensures adults have access to honeydew and that newly hatched larvae have an immediate food source. If all pests are eradicated, lacewings will simply disperse to find a more reliable hunting ground.