If a flowering plant can grow to weigh 250 tons, cover more than an acre of property and contain more than 1.5 million blossoms, it can surely accommodate its share of insects. When Alice Brugman planted wisteria in the late 1800s in her Sierra Madre garden, she could not have anticipated the enormity of the plant, which still thrives today. Although exceptional, her plant shows the resilience and persistence of this perennial vine. Wisteria attracts many insect species with its abundant blossoms and strong fragrance. Some of those insects seek a nectar feast or a protective hiding place, while others prey on the nectar-feeders. Wasps in wisteria are usually predatory.
Wisteria is a woody vine that grows to more than 25 feet, climbing trees, buildings and landscaping structures. Its loosely hanging flower clusters range in size from 6 to 18 inches. Blossoms are typically pale purple, but some cultivars are white, pink or violet-blue. There are 10 species of the genus Wisteria in the Fabaceae, or pea, family. Only two species are native to the U.S., while the rest are native to Asia. Two imported Asian species are common in American gardens -- Chinese (Wisteria sinensis) and Japanese (Wisteria floribunda) wisteria.
Ambitious gardeners plant wisteria for its hardiness, longevity and showy floral display. However, this plant can quickly become a gardener’s nemesis. Under the right conditions of full sunlight and well-drained soil, wisteria grows fast and strong. Long-lived plants become so heavy that they crush their supporting structures. Its strong and extensive root system easily breaks through concrete over time. Wisteria chokes and kills native trees with its aggressive twining growth. Vigilant pruning and seed collection are necessary to prevent the plant from becoming destructive to your garden and your neighbors' property. The plant is so aggressive that Florida has declared wisteria an invasive species. Before planting any wisteria cultivar, ensure that it is permitted in your location and that you can commit to the extensive, preventive care that it requires.
Wasp is a general term applied to several families of insects belonging to the order Hymenoptera. They have four membranous wings, long antennae and chewing mouthparts. Female wasps have an ovipositor for laying eggs and sometimes stinging. Depending on the species, ovipositors can be tiny or several times the insect’s length. There are thousands of North American wasp species, ranging in size from near microscopic in the family Trichogrammatidae to the 1 1/2-inch long Sphecid wasps. This diverse group of insects has a wide range of habitats and feeding behaviors. Gardeners value wasps for their pest control abilities. Parasitic wasps help keep plant pest populations low.
Wasps and Wisteria
Wisteria is an ideal place for a wasp nest. Vespid, or paper, wasps build nests on trellises, arbors or directly on the woody stems of the vines. The multiple blossoms provide protection and foraging space for these insect-eating wasps and their offspring. Parasitic wasps lay their eggs inside aphids, a known pest of wisteria. As the eggs hatch, the larvae eat the aphid from the inside. Wasps are not a pest of wisteria. Their presence around the plant is incidental to the plant’s success.
- Sierra Madre Chamber of Commerce: 2012 Wistaria Festival
- University of California Agriculture and Natural Resources: Pests in Gardens and Landscapes: Wisteria
- California Invasive Plant Council: Don’t Plant a Pest: Shrubs of the Bay Area Region
- University of Florida Centre for Aquatic and Invasive Plants: Wisteria
- United States Department of Agriculture Natural Resources Conservation Service: Plants Profile: Wisteria Nutt.
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