Leafy Spurge Hawkmoth

Biocontrol Agent Factsheet

Leafy Spurge Hawkmoth (Hyles euphorbiae L.) is a biocontrol agent used to control the invasive weed leafy spurge. The larvae  feed on leafy spurge leaves starting from near the bottom of the plant and moving to the top. Once an individual plant is stripped of nearly all or all of the leaves, the larvae drop to the ground and move to the next stem.

Overview

Pests Targeted: Leafy spurge
Pest Stage: Leaves, starting at the bottom of the plant
Commercially Available? No
Scientific Name: Hyles euphorbiae L.
Biocontrol Agent Type: Weed-feeder

Large orange and black colored larva feeding on leafy spurge leaves.
Leafy spurge hawk moth larvae feeding on leafy spurge foliage. Photo credit: USDA-APHIS-PPQ.

Common Names

Leafy spurge hawkmoth

Relative effectiveness

Not effective. Dense populations of the hawkmoth look spectacular as they denude leafy spurge stands, but this feeding does not harm the perennial leafy spurge plant which readily regrows. Most often, moth populations tend to be too small to support collection for redistribution to other leafy spurge infestations.

Where to use

Pasture or rangeland

Leafy spurge hawkmoths do best in open areas with dense stands of leafy spurge

About Leafy spurge hawkmoth

The leafy spurge hawkmoth was the first biocontrol agent introduced into the US to control leafy spurge. The insect was first released in 1966 near Bozeman, MT and quickly established. First-generation adults emerge in early to midsummer. The larvae feed on leafy spurge leaves starting from near the bottom of the plant and moving to the top. Once an individual plant is stripped of nearly all or all of the leaves, the larvae drop to the ground and move to the next stem. Hawkmoth larvae can be found feeding on leafy spurge from mid-June to mid-September. There are usually two generations per year.

  • Native/Non-native: Non-native
  • Preferred climate: arid
  • Region: Throughout the Northern Great Plains and Rocky Mountains where leafy spurge occurs.
  • Established: Yes
  • Where established: The insect has established in low numbers in most places leafy spurge is found.

Leafy spurge hawkmoth Appearance

Adult hawkmoths are large and measure 1-1.25 in (2-3 cm) long with a 2-3 in (5-7 cm) wingspan. Adults are olive brown with white and black markings. The larvae can grow up to 4 in (10 cm) in length and look similar to a tomato hornworm. Larvae change color as they mature. The second and third instars (development stages) are greenish-yellow and the fourth and fifth instars are a combination of black, white, red, and yellow. 

Adults are often seen feeding on the nectar of leafy spurge flowers. Although the larvae feed exclusively on leafy spurge, adult hawkmoths seek nectar from many types of flowers including the endangered species the western prairie fringed orchid. Leafy spurge has invaded the remaining acreage of the orchid habitat and may be the greatest threat to the species survival. Thus, initially introduced to control an invasive weed, the hawkmoth is also helping the survival of an endangered species through pollination

Large pink, brown, and white leafy spurge hawkmoth adult sitting on a plant.

Adult leafy spurge hawkmoth.

Black, green, and yellow caterpillar with white spots and a horn at its rear end crawling along a stem.

Leafy spurge hawk moth larvae feeding on leafy spurge foliage.

Black, red, and yellow caterpillar with white spots and a horn at its rear end crawling along a stem.

Leafy spurge hawkmoth larva feeding on leafy spurge foliage.

Life Cycle

The leafy spurge hawk moth has one to two generations per year. Pupae overwinter in the soil.  First-generation adults emerge in early to mid-June; if a second generation of adults occurs, it will do so sometime from late August through September. Larvae emerge in 1 to 2 weeks depending on temperatures. Mature fifth-instar larvae drop to the ground and enter the soil to pupate. Blue bars indicate overwintering stage. 

Leafy spurge hawkmoth pupae overwinter in the soil, emerge in mid-June and lay eggs. Larvae hatch from the eggs and turn into pupae in September. They spend the fall and winter in this stage. Depending on the season, there could be a second generation of adults in late August or September.
Leafy spurge hawkmoth pupae overwinter in the soil, emerge in mid-June and lay eggs. Larvae hatch from the eggs and turn into pupae in September. They spend the fall and winter in this stage.

How to use leafy spurge hawkmoth for biocontrol

Biocontrol category: Classical - released once and persists

Maximizing effectiveness: This biocontrol agent is unlikely to be effective. Several problems occurred with this insect after introduction. First, the insect was introduced with an internal parasite that kills the larvae, especially prevalent when there are large numbers of larvae in one area. Second, mice and other rodents feed on the pupa (resting stage) found near the soil surface.  

Pest stage: Leaves

Mode of action: Weed feeder

Compatibility: Leafy spurge hawkmoths are often found where Aphthona spp. flea beetles have established.  This insect is not compatible with herbicide application or grazing.

Commercially available: No

About Leafy spurge (Euphorbia esula L.)

Leafy spurge is a long-lived perennial weed that spreads by both root and seed. The weed invades rangeland, wildlands, roadsides and cropland. The plant grows 2 to 3 feet tall, has linear shaped blue-green leaves, and contains a white milky latex throughout the top growth. Leafy spurge produces a flat top cluster of yellow bracts that surround the inconspicuous true flower. 

Leafy spurge Damage

Leafy spurge replaces other plants (including native species) resulting in negative impacts on many species within the ecosystem. The presence of leafy spurge in pastures or rangelands also reduces the suitability of land for grazing domesticated animals like cattle and horses. They avoid eating the plants because the latex they produce contains a toxic compound.

Plant with narrow leaves and small yellow flowers.

Leafy spurge in flowering growth stage.

Field full of leafy spurge plants

Leafy spurge can become a near monoculture in the pastures and rangeland of the Northern Great Plains.

Author

Rodney G. Lym
Professor emeritus, North Dakota State University

Date: December 2021

  • Leafy spurge hawk moth larvae, USDA-APHIS-PPQ
  • Leafy spurge hawkmoth larva feeding on leafy spurge foliage. Photo credit: Whitney Cranshaw, Colorado State University, Bugwood.org
  • Leafy spurge hawkmoth larva feeding on leafy spurge foliage. Photo credit: Whitney Cranshaw, Colorado State University, Bugwood.org
  • Adult leafy spurge hawkmoth. Photo credit: USDA-APHIS-PPQ.

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