Aphthona lacertosa flea beetle

Biocontrol Agent Factsheet

The brown legged leafy spurge flea beetle (Aphthona lacertosa) is a beetle that feeds on leafy spurge (Euphorbia esula), an invasive weed. 

Common Names

  • brown legged leafy spurge flea beetle
  • black leafy spurge flea beetle

Relative effectiveness

Brown legged leafy spurge flea beetle (Aphthona lacertosa) has been the most effective Aphthona flea beetle released for leafy spurge control. The agent is widely adapted to both clay and sandy loam soils and has been established in all geographic areas where leafy spurge is found. 

Where to use

Pasture or rangeland

Areas with well-drained soil and only moderate densities of leafy spurge (see 'How to use' section)

About Aphthona lacertosa

Brown legged leafy spurge flea beetle (A. lacertosa) adults feed on leafy spurge top-growth but the main damage to the plant is from larvae feeding on the roots. You can only see the damage by digging leafy spurge plants up. Larvae overwinter in the soil, pupate and emerge from the soil in early summer. The adult females lay eggs on the soil surface and larvae hatch in about 8 days. The larvae then move to the fine feeder roots of leafy spurge. They go through three instars before beginning to feed on root buds. There is one generation per year. It is ironic that this agent has become the most effective Aphthona spp. as it was identified as A. czwalinae when first released, but the introduction was later discovered to be a mixed population. 

  • Native/Non-native: Non-native
  • Preferred climate: arid
  • Region: Generally, most productive in the Northern Great Plains of the US and Canada.
  • Established: Yes
  • Where established: North Central Great Plains and adjacent Rocky Mountain regions of US and Canada.

Aphthona lacertosa Appearance

Brown legged leafy spurge flea beetles (Aphthona lacertosa) are 2.5 to 3.5 mm in length and mostly black in color with brown hind legs. Adults typically hop when disturbed but are capable of flight. Larvae are 1-6 mm long, with short legs, yellow heads, and creamy-white bodies.

black colored flea beetle with brown legs crawling on a leaf

Adult Aphthona lacertosa or brown legged leafy spurge flea beetle.

Large white colored Aphthona larvae laying on soil.

Third instar Aphthona larvae which will pupate and overwinter in the soil.

Numerous black flea beetles feeding on leafy spurge leaves.

Mixed population of two species of leafy spurge flea beetles (A. lacertosa and A. czwalinae) feeding on leafy spurge topgrowth. While a source of food for the adults, this type of feeding has no effect on long-term leafy spurge control. It is the damage to leafy spurge roots that controls this weed.

How to Use Aphthona lacertosa

Biocontrol category: Classical - released once and persists

When to use: Before moving leafy spurge flea beetles, you should confirm with your local regulatory agency that this is permitted. Flea beetles should be collected as adults from established stands and moved to establish new populations. The “nursery” area should be monitored from late-June through mid-July when adults emerge from the soil and begin feeding on leafy spurge topgrowth. The best time to collect flea beetles for redistribution is from 10 AM to 3 PM when the air temperature is greater than 70 F, there is little or no wind, and the skies are generally sunny. Leafy spurge should be dry before collecting flea beetles because wet conditions will make sweeping difficult and reduces the adult survival during transportation.

Where to use: Leafy spurge flea beetle establishment is best on silt loam, silt clay loam, clay loam and clay soils with an organic matter content of 6 to 9.5 percent. In addition, the release area needs to be well drained and not subject to frequent prolonged flooding or standing water, which will kill the larvae. Initial releases have been most successful on south-facing slopes in moderate densities of leafy spurge (60 to 90 stems per square yard) with minimal grass cover and thatch. Establishment in dense leafy spurge stands is often difficult. 

Rate: Several hundred to 1000 adults should be released per spot as a group rather than spreading them thinly through the leafy spurge infestation. Flea beetles establish best in moderate densities of leafy spurge (60 to 90 stems per square yard) with minimal grass cover and thatch. Establishment in dense leafy spurge stands is often difficult. Release flea beetles on the margins of dense infestations and allow the insect to work into denser stands as the population builds.

Maximizing effectiveness: Once collected, the flea beetles should be transported in paper bags or containers. Do not use plastic containers because moisture condensing on the plastic can drown the insects. Add some leafy spurge to the container and place in a cooler containing ice or ice packs. Do not allow the containers or cooler to sit in the sun. Flea beetles should be released as soon as possible after collection. Releasing the same day as collection is ideal; however, insects can survive several days when refrigerated at 40 to 45 F. The more similar collection and release environments are, the sooner the flea beetles are likely to become established and begin to control leafy spurge.

Pest stage: Adults feed on leafy spurge top-growth but the main damage to the plant is from larvae feeding on the roots (from the time eggs are laid and hatched in mid-summer until near soil freeze-up in mid-October).

Mode of action: Weed-feeder

Compatibility: Several options are available for leafy spurge control besides biological control agents, including the use of herbicides, grazing, seeding competitive grasses, and cultivation. Before beginning a leafy spurge control program, consider the best options suited for the situation and utilize more than one. Most successful control programs have used multiple control methods combined over several years. (Any time you use a pesticide, you must read and follow the label directions and comply with all applicable laws and regulations related to pesticide use. Also be sure that any pesticide used is approved for use in your country and state/province.)

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.

Cross-section of plant root showing feeding holes from Aphthona larvae.

Aphthona larvae feed on leafy spurge roots. The first instar feeds on fine feeder roots while the third and final instar feeds on and destroys leafy spurge root buds which greatly reduce weed density the following season.

Consult the following extension publications for more detailed information concerning biological control of leafy spurge:

Author

Rodney G. Lym
Professor emeritus, North Dakota State University

Date: November 2021

USDA-APHIS-PPQ

  • Adult Aphthona lacertosa or brown legged leafy spurge flea beetle

Rodney G. Lym

  • Third instar Aphthona larvae
  • Mixed population of two species of leafy spurge flea beetles
  • General Aphthona spp. flea beetle life cycle
  • Aphthona larvae feeding  on leafy spurge roots
  • Leafy spurge in flowering growth stage
  • Leafy spurge field

John M. Randall, The Nature Conservancy, Bugwood.org

  • Leafy spurge in flowering growth stage

Mark Schwarzlander, University of Idaho, Bugwood.org

  • Adult Aphthona lacertosa or brown legged leafy spurge flea beetle.