Species Chrysolina hyperici - St. Johnswort Beetle

body length 4-6 mm

Adult: body oval, metallic green or bronze with punctate elytra

Larva: body humped, initially orange, later grayish, but not often seen, as they feed mostly at night and hide during the day in leaf buds, under the plant, or in the soil

Nova Scotia to Ontario, plus British Columbia and adjacent parts of United States

native to Europe and Asia

on St. Johnswort plants

adults present in June and again in fall

larvae feed during the night on shoot tips and basal and developing leaves of St. Johnswort (Hypericum spp.)

adults feed in clusters during the day on flower buds and terminal leaves of St. Johnswort

up to 2,000 reddish eggs laid singly or in small clusters on basal leaves of hostplant, mostly in fall; larvae hatch in spring; pupation occurs in the soil in late spring; adults emerge in June to feed, then enter the soil; they emerge again in fall and resume feeding; overwinters as an adult and egg

Introduced to North America to control growth and spread of St. Johnswort, and to reduce the spread of native St. Johnswort disease (Colletotrichum gloeosporioides)

Adults are more tolerant of cooler and wetter summers than the related Chrysolina quadrigemina, whose larvae and adults are killed by May frosts, and whose adult dormancy is disrupted by summer rains.

Klamath Weed Beetle (Chrysolina quadrigemina) is larger (6-7 mm) and may be purple, blue, or nearly black, in addition to metallic bronze and green

live adult images plus description, biology, impact, origin, similar species, distribution, references (Agriculture Canada)

common name reference plus description, biology, overview (Montana War on Weeds)

description plus biology and foodplants (British Columbia Ministry of Forests)

preserved adult images of male and females (European Chrysomelidae, U. of Wroclaw, Poland)

adult images (Malcolm Storey, UK)