Summer Lilac, Orange Eye Butterfly Bush
General: Butterfly Bush is a rapid-growing deciduous shrub that is often planted in gardens to attract butterflies.
Flowers: Butterfly Bush has clusters of tubular flowers with four petals, that are arranged in dense pointed clumps at the end of branches. The flowers have an orange centre and are found in a variety of colours such as white, pink, purple, orange, red, and blue.
Stem: The arching stems can reach up to 5 metres in height. Young stems are green, while older stems have a grey-brown and peeling bark.
Leaves: The leaves are semi-erect to falling, opposite to one another on the branches, and lance-shaped. They are approximately 10-30 cm in length, green in colour, and have a velvety texture due to a fuzzy underside.
Fruits: Butterfly Bush produces small and ovate pods, that become dark brown in colour and open at the ends once they mature. There are about 500-1000 small, lightweight, and winged seeds per pod.
California Lilac (Ceanothus spp.): There are about 50-60 species in this genus, which tend to have smaller shiny leaves.
Meyer Lilac (Syringa meyeri): Leaves are smaller and about an inch in length, with slightly wavy margins.
Lilacs bloom in the middle of spring, while Butterfly Bush blooms from June to September.
Habitat and Origin
Butterfly Bush is a native species to China and was introduced to North America as a garden ornamental. As both a habitat generalist and a pioneering species, Butterfly Bush can withstand challenging environmental conditions such as full sun exposure, and soil that is low in moisture and poor in nutrients. Therefore, this species can often be found in recently logged or burned forests, railways, road edges, cliffs, building sites, and open or disturbed sites. Butterfly Bush also thrives in ecosystems with high soil moisture such as riparian habitats and coastal forest edges.
Propagation & Vectors of Spread
For Butterfly Bush, propagation occurs by both vegetative and seed production. Butterfly Bush can sprout new plants from broken branches, cut stems, or from the rootstock. Furthermore, this plant matures rapidly and can produce seeds during the first year of growth. One flower head can produce as many as 40,00 seeds, which remain viable in the soil for 3- 5 years. Butterfly Bush has spread around the world due to its popularity in the horticulture industry. Once introduced to an area, further spread to new locations can occur by wind, water, vehicles, equipment, and machinery.
Ecological and Economic Impacts
- Crowds out native vegetation by forming dense thickets
- Alters the nitrogen and phosphorous amounts in the soil, which displaces native species further.
- DOES NOT provide suitable habitat nor food sources for butterflies, as it only provides nectar for adult butterflies. Butterfly larvae cannot actually survive on Butterfly Bush. By competing with native vegetation that acts as a food source for the larvae, Butterfly Bush can actually have a negative impact on butterfly populations.
- Impedes forest regeneration and disrupts patterns of ecological succession to ultimately decrease timber yields in the forestry industry.
What Can I Do?
Butterfly Bush is found in Squamish and Whistler so PREVENTION is key:
Learn to identify Butterfly Bush: use the images presented in this profile page to learn how to identify Butterfly Bush.
What to do if you spot it: You can report any Butterfly Bush sighting by clicking here.
- Regularly monitor properties for weed infestations.
- Ensure soil and gravel are uncontaminated before transport.
- Ensure all plant parts are bagged or covered to prevent spread during transport to designated disposal sites.
- Since the seeds require exposed soil to germinate, minimize soil disturbances and use seed mixes with dense, early colonization (e.g. alfalfa or barley) to re-vegetate exposed soil and resist invasion.
- Unload, park or store equipment or vehicles in infested areas; remove plant material from any equipment, vehicles or clothing used in such areas and wash equipment and vehicles at designated cleaning sites before leaving infested areas.
- Plant Butterfly Bush in a garden, no matter how well-contained its enclosure may seem.
- Compost any plant material. Instead, dispose of Butterfly Bush in the general/household waste stream at the landfill as the seeds will be able to persist the composting process.
- Move soil, gravel, or fill material that has been contaminated with Butterfly Bush.
For mechanical control, small plants can be hand-pulled where the soil is moist. Remove larger bushes by cutting the plant at the base and digging up the stump, and then proceeding to cover the stump with a thick plastic bag or mulch to prevent regeneration. Remove spent flower heads in the fall before seeds are dispersed.
Spraying Butterfly Bush with a brush-control herbicide is somewhat effective. More effective treatment involves cutting the trunk of the bush off at the base and applying concentrated glyphosate or triclopyr to the cut surface. All herbicide applications should be monitored over successive years as follow-up treatments may be required, and to evaluate the efficacy of the chemical control method.
We recommend that any herbicide application is carried out by a person holding a valid BC Pesticide Applicator Certificate. Before selecting and applying herbicides, you must review and follow herbicide labels and application rates; municipal, regional, provincial and federal laws and regulations; species-specific treatment recommendations, and site-specific goals and objectives.
Goat grazing may be effective with other control methods, but this treatment alone will not kill or eradicate Butterfly Bush.
- King County, https://www.kingcounty.gov/services/environment/animals-and-plants/noxious-weeds/weed-identification/butterfly-bush.aspx
- Invasive Species Council of BC, https://bcinvasives.ca/invasive-species/identify/invasive-plants/butterfly-bush
- Invasive Plant Atlas, https://www.invasiveplantatlas.org/subject.html?sub=11608
- CABI, https://www.cabi.org/isc/datasheet/10314
- Coastal Invasive Species Committee, http://www.coastalisc.com/priority-invasive-plants/butterfly-bush
- North American Butterfly Association, https://www.naba.org/pubs/bg172/bg172_Butterflybush_Issue.pdf