Soil Feeders - Green June Beetle (GJB)

GREEN JUNE BEETLE (GJB)
aka: Fig Eater
scientific name: Cotinis nitida

FIELD KEYS
Hosts: Most grass species
Site symptoms: Irregular turf areas die under heat or moisture stress from damage caused by disrupted roots or thinned thatch layers. Grubs borrow in soil leaving loose soil and anthill-like mounds 1 1/2 to 2-inches high.
Plant symptoms: Above-ground plant structure shows no obvious damage or other symptoms, however root system may show extensive disruption from grub tunneling and burrowing activities. Site keys: Locations with high soil organic content or where manure or compost has been used in site management or construction.

SPECIMEN ID
Immatures are short legged white grubs with tan heads that range in size from 1/3 inch for newly hatched first instars to 2-inches for fully growth third instars. Adults are large, broad-bodied beetles (1 inch long and 1/2 inch wide) with iridescent green heads and mottled green and brown wing covers.

SCOUTING TIPS
GJB do not directly feed on grass roots, rather turf damage results from burrowing and tunneling activities of these large grubs. At night, the grubs emerge from their borrows and crawl on their backs (up to 65 feet per night) while looking for decaying organic matter on the soil surface to feed upon. Look for small mounds of soil at burrow entrances. Also their crawling activities often leave trails in sand, loose soil or on dew-covered surfaces. Adults can be captured in light traps or may be found feeding on sugary thin-skinned fruits such as figs, grapes and peaches. Begin grub scouting 3-4 weeks after adult emergence.

CONTROL STRATEGIES
Cultural: Monitor adult and larval populations as this pest tends to follow a 3-6 year damage cycle. Avoid using manures or composts in the management or construction of turf sites. Manage these sites for maximum plant recovery and overseed with stolen or rhizome producing grass species.
Chemical: Once grub scouting activities indicate per square foot grub population of 6-8 on tall cut turf, consider making control applications to infested sites. At more vulnerable sites or areas where their burrowing activities can disrupt site usage (golf and sports sites), applications may begin two weeks after adult emergence. Early applications also reduce the chance of large grubs surfacing and dying.

Growth stages: egg - grub (three instars)* - pupa - adult*
* - treatable stages

Life cycle: 1 year life cycle grub - pupa - adult - egg - grub
Sequence: grub - pupa - adult - egg - grub