The above photo was taken by Albert LaSalle, Colorado Master Gardener, of the first specimen located in Mesa County, July 23, 2002. Albert is in charge of the CSU Extension Tri River Area JB trapping program.

Introduction:

Japanese beetle trapping has been conducted in western Colorado for many years, with the only captures associated with imported nursery stock. Past captures of mostly individual specimens were from Mesa, Jefferson, Boulder, and Larimer Counties. This eastern pest was not thought to be able to survive in our dry climate because grubs require moist soil conditions. Dry winters had been thought to limit or possibly eliminate any populations. Moisture conditions associated with irrigated lawns, however, may be sufficient to allow for survival of Japanese beetle larvae.

An infestation of Japanese beetles Popillia japonica was identified in Palisade (Mesa County) in the summer of 2002. The initial discovery was based on a single adult Japanese beetle taken to Bookcliff Gardens, and forwarded to the Extension office on July 23. The identification was verified by Dr. Boris Kondratieff, entomologist at Colorado State University on July 24. A series of Japanese beetle traps were placed in the vicinity of the initial beetle capture in Palisade during the last week of July, 2002 by Colorado Department of Agriculture personnel. Eighty-five beetles were captured over the course of the following two weeks. Initial survey results indicate that the Palisade infestation is confined to a 10 block area of Palisade. Eradication attempts in California, Nevada, Idaho and Oregon have been successful in the past. It is critical to identify breeding sites for eradication attempts to be successful.

Update:
Colorado Department of Agriculture staff conducted a mass trapping program in Palisade during the summer of 2003. As of September 15, 2003, 1218 adult japanese Beetles had been captured through this program.

The Colorado State University Extension was responsible for placing traps throughout other areas of Mesa County. JB traps were also placed in Delta and Montrose counties. No Japanese beetles were captured through the CSU Extension effort indicating Palisade is the only location in Mesa, Delta and Montrose counties where a Japanese Beetle infestation has been identified. Additional trapping efforts will be undertaken in 2004.

The Insect:

The adult Japanese beetle is a little less than 1/2 inch long and has a shiny, metallic-green body and bronze-colored outer wings. The beetle has six small tufts of white hair along the sides and back of its body under the edges of its wings. The males usually are slightly smaller than the females. You are most likely to see the adults in mid summer. During the adult feeding period, females intermittently leave plants, burrow about 3 inches into the ground--usually into turf--and lay a few eggs. This cycle is repeated until the female lays 40 to 60 eggs. By mid to late summer, the eggs hatch, and the young grubs begin to feed. Each grub is about an inch long when fully grown and lies in a curled position. In late autumn, the grubs burrow 4 to 8 inches into the soil and remain inactive all winter. This insect spends about 10 months of the year in the ground in the larval stage. In early spring, the grubs return to the turf and continue to feed on roots until late spring, when they change into pupae. In about 2 weeks, the pupae become adult beetles and emerge from the ground. This life cycle takes a year.

Your help is needed:

If you live in Western Colorado and see a Japanese beetle, please collect the specimen and deliver it to the Mesa County Extension office at the Mesa County Fairgrounds, or call (970) 244-1834. For information on the biology and management of Japanese beetles, please visit: http://www.pueblo.gsa.gov/cic_text/housing/japanese-beetle/jbeetle.html

¹ Curtis E. Swift, Ph.D., Horticulture Agent, Robert Hammon, Entomologist, and Susan Rose, Horticulture Technician, Colorado State University Extension, Tri River Area.

Bjostad, L., and Bishop. J. Agricultural Pest Survey Annual Narrative Report Colorado. Fiscal Year 2002; 1 October 2001 to 30 September 2002. Colorado State University Department of Bioagricultural Sciences and Pest Management.