Aplocera plagiata 
<<back to St. Johnswort
Common Name
None widely accepted; known locally and among some biocontrol workers as St. Johnswort moth
Weed Impacted
Larvae feed on the leaves of St. Johnswort (Klamath weed, goatweed). Large populations of larvae can defoliate plants, inhibiting flower formation and seed production.
Insect Description
Adults are gray, triangular moths with characteristic dark bands across the wings. Wingspan is 23-25 mm (approx. 1 in). Larvae are weakly striped, reddish-brown “inchworm” type caterpillars. Mature larvae are about 2.5 cm (1 in) long.
Life Cycle
This moth has two generations per year. First-generation adults emerge in early summer and egg-laying occurs on foliage soon after emergence. First-generation larvae are present during July. Second-generation adults emerge in mid- to late summer and second-generation larvae are present from August through September. Cool fall temperatures slow larval development and cause the caterpillars to move under soil litter or into the soil where they overwinter and then pupate in late spring of the following year.
Availability
Aplocera plagiata is present in eastern Washington, eastern Oregon, and northern Idaho but available on a limited basis. Larvae are collected throughout the summer. To inquire about availability and to request this biocontrol agent, please download, complete and submit this form.
Comments
This agent needs warm, dry areas with a summer season long enough to complete both generations. It does best in dry, open areas with sandy or rocky ground and in limestone areas.
Using the Agent: Integrated Weed Management (IWM)
Because the A. plagiata utilizes the same food resources as Chrysolina spp., caterpillars should not be released where Chrysolina is already present and controlling the weed. The best sites for release and establishment of A. plagiata may be in the warm, dry, rocky areas east of the Cascades.
Moths should only be released at sites where St. Johnswort infestations are large and immediate eradication of the weed is not the primary objective. Smaller or satellite plant populations can either be hand-pulled or sprayed. Consult with your county weed office, Extension office or an IWM practitioner to determine which herbicide treatments are safe and appropriate.
Burning is not recommended as it can actually increase plant growth. Mowing is not an effective means of control and is generally not recommended. Mowing while insects are active will work against any potential agent impacts on the weed, either by destroying the agents outright or by removing their source for growth and development.
Any management of St. Johnswort should include revegetation with native or other desirable plants. Revegetation promotes competition between plants, which stresses weeds and allows for more effective treatment. For more information about revegetation, click here.
References
Coombs, E. M., J. K. Clark, G. L. Piper, and A. F. Cofrancesco, Jr. 2004. Biological Control of Invasive Plants in the United States. Western Society of Weed Science, Oregon State Univ. Press, Corvallis.
Photo Credits
Aplocera plagiata adult - Nick Greatorex-Davies, ukmoths.org, http://ukmoths.org.uk/show.php?bf=1867
Aplocera plagiata larva - N. Poritz, bio-control.com, http://www.bio-control.com/photos/Appl.jpg
Secondary content using h2 tag. Column 2
Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.
Heading using the h3tag
Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.