By Amy Yarger, Horticulture Director
A healthy landscape will foster a complete food web with producers, predators, pollinators, decomposers, and yes, even plant-eaters. When the damage from herbivores exceeds the agreed-upon threshold, horticulturists have a toolbox full of possible management strategies. Fortunate is the horticulturist, however, who can encourage nature to “take its course.” Garden food webs may already include predators and parasites that can make short work of many common garden pests. Some landscapes support diverse trophic levels better than others, however.
It will probably come as no surprise that gardens that sport plants of different heights, shapes, chemical profiles and bloom seasons tend to provide more ecological niches for beneficial insects. The most diverse gardens in structure and species will have food and shelter available for insects of different sizes, different life cycles and different habits, mimicking the natural environment. Compare the complexity of this sort of “wild” garden to the old school monocultures of bedding plants popular decades ago.
Structural diversity not only supports more different kinds of beneficial insects, but supports the entire, often complicated, life cycles of these “good bugs”. Juvenile predators, such as syrphid flies, ladybugs and green lacewings, have entirely distinct needs from their parents. In many cases, the larva are hungrier predators than the adults; one larval ladybug can eat 40 aphids a day! Allowing some moist spots, leaf litter, loose bark or other potential habitats can provide shelter for these “hidden” (and often misunderstood) predators. Including small-flowered plants such as fennel and lovage may add some nectar to the diet of adult ladybugs and lacewings, making it more likely that they will stick around and reproduce.
Most of us understand that many chemicals in the garden environment can negatively impact common insect predators such as ladybugs and syrphid flies, and professionals have become, by and large, more careful about chemical pesticide use. The next step may well be to look at how we design and maintain our gardens from an ecological perspective. These habitat gardens can be even more attractive and engaging than the traditional flowerbeds often seen in public places, drawing people to investigate and appreciate the natural world in a safe space. They can also serve as spots for educational programming and citizen science. I have a feeling many of us are already approaching our landscapes from this perspective, and I’d love to hear about your successes and challenges!
