BIOLOGY: Adults are long and slender (10-12 mm) with long black antennae, red heads, and grey bodies. They are active fliers. Adults lay eggs in June and July. Females girdle the stems and deposit one egg per shoot. Females can produce 60 eggs in their lifetime. Eggs hatch in 7-10 days. Larvae mine the stem and overwinter in the root crown. Larvae are obviously segmented and up to 20 mm long. Pupation occurs in the root crown in May with adult emergence in June.
DESTRUCTIVE STAGE: Larvae (stem boring)
IMPACT TO HOST: Adults girdle stems, causing minor damage. Larvae can kill an entire plant by root mining. When used with Apthona spp. The red-headed stem borer shows excellent control.
REDISTRIBUTION: Adults can be collected in sweep nets from along with Apthona spp. in June and July. A collection of only 50 beetles will be effective in a leafy spurge patch.
BIOLOGY: Adults are found on plants from May through July. They vary in color from black (A. czwalinae) to copper (A. flava) with enlarged hind femurs. Females lay eggs in the ground from July to September. Eggs hatch in 16-17 days. Larvae undergo 3 instars. The larvae are small (1-5 mm long) and white with a brown head. Third instar larvae overwinter and pupate in the soil in late spring.
DESTRUCTIVE STAGE: Mature larvae (feeding on root fibers) and adults (leaf feeding)
IMPACT TO HOST: Adult feeding reduces photosynthetic capability. Larval feeding reduces the ability of leafy spurge to take in nutrients. Impact can be significant and when used with an integrated pest management strategy, leafy spurge infestations can be controlled in 5-7 years.
REDISTRIBUTION: Adults can be collected in sweep nets from May – July. Releases should be made on small thin stands of leafy spurge or on the edge of a large infestation. Ant predation can be a problem in establishing this biological control. If this agent fails to establish after one year, purchase pure collections commercially and treat your release site for ants in the fall before releasing biological control agents the following spring.
BACKGROUND: A native plant of Eurasia, leafy spurge is an aggressive invader of pastures, rangeland, stream banks, and waste areas. It reproduces by seed and rootstock. It is toxic to cattle and may result in their death.
OTHER COMMON NAMES:
DESCRIPTION: This creeping herbaceous perennial plant grows up to 3 feet tall. The leaves are narrow, and 1 to 4 inches long. In late spring, yellow-green flower bracts appear, which cup tiny, inconspicuous flowers that develop in early summer. Seeds are contained in a three-celled capsule, with one seed per cell. When dry, capsules can shoot seeds up to 15 feet from parent plant. Stems exude a milky fluid when damaged. An extensive root system, up to 20 feet long and more than 14 feet deep, with multiple shoot-producing buds, makes this plant very difficult to control.
CONTROL: Biocontrol is extensive and control is fair to excellent. Herbicides can offer fair to good control, especially when combined with biocontrol. Apply herbicides from spring to the killing frost.
