BIOLOGY: Adults emerge in late summer and live for up to 3 years. Adults are 8-12 mm long. Eggs are laid from June – August. Adults lay 1-3 eggs per day. Eggs are deposited in soil and hatch after 11 days. Larval stages may last for 1-2 years.
DESTRUCTIVE STAGE: Adult (leaf feeding) and larvae (root mining)
IMPACT TO HOST: Larvae mine roots while adults feed on foliage. Small roots can be destroyed within two years while large roots may die after several years of infestation.
REDISTRIBUTION: Adults are nocturnal and must be collected at night. Night collection can be difficult. Some laboratories rear H. transversovittatus on artificial diets. These are available free by contacting Amber Richman (435-830-4146). Adults can be released on plants or eggs can be released on roots. A typical release is 100-200 weevils. These should be used with Galerucella spp. for maximum control.
BIOLOGY: Adults emerge from soil in April and June. Adults are 3-5 mm long and orange with brown stripes along the wings. Eggs are laid from May–September on stems and leaves in clusters of 3-6. Females produce up to 400 eggs. Eggs hatch in 12 days. Larvae feed on buds and leaves for 14 days. Larvae are small (3-4mm) and light green with brown to black spots. Pupation takes 7 days and occurs in the soil or in the spongy tissue of stems in standing water.
DESTRUCTIVE STAGE: Adults and larvae (feeding on buds and leaves)
IMPACT TO HOST: Adult and larval feeding results in stunted plants and reduced seed production. In some areas of Utah, complete control of purple loosestrife has been attributed entirely to biological control.
REDISTRIBUTION: Adults can be collected in sweep nets or by picking adults off of plants. A typical release is 250 adults. Collection is best in late April or early May. Adults overwinter in the ground so continuously flooded areas are not ideal for release. Also, beetles are very susceptible to insecticides used for mosquito abatement. If sprayed, most beetles will die.
BACKGROUND: Purple loosestrife is a European plant probably introduced to the United States as an ornamental. It reproduces both by seed and creeping rootstocks. Infestations can impede water flow and replace beneficial plants, and thus displace wildlife. It can be found in shallow, marshy wetland areas and ditches.
OTHER COMMON NAMES:
DESCRIPTION: Purple loosestrife is a semi-aquatic creeping herbaceous perennial growing 6 to 8 feet tall. There are five to seven petals on rose purple flowers that appear in columns along the upper end of stems. Leaves are lance shaped with smooth margins up to 5 inches long. Bloom is in midsummer.
CONTROL: Biocontrol is limited in availability but control can be good to excellent. Herbicides with an aquatic label can offer fair to good control.