Rose stem girdler (2014)

Justin O’Dea

Agrilus cuprescens

This buprestid beetle is a pest of Rosa and Rubus spp. (domestic and wild rose, Himalayan blackberry, and raspberry). Though recently reported in the PNW, it seems that it has been on this continent since late 1800. This pest was found in Idaho in the 1970s, first found in Oregon in 1994 and in Washington in 2014.

Pest description and damage The adult beetles are small
(< 0.25 inch) metallic black to coppery and oblong-shaped. The wings lie flat over the body, meeting in a straight line for half the distance before parting slightly towards the back end. The round, flattened eggs are laid on the bark and covered with a protective yellow substance. The white, segmented larvae have a flattened and expanded head with black mouthparts and two spines at the tail end of its cream-colored body. There is a constriction between each of the larval segments. Pupae are 0.25 inch, shiny and white with external body features visible. Adults feed on edges of the foliage, creating a ratty appearance that could be mistaken for root weevil damage. This damage is not significant. Larvae hatch and tunnel from the bottom of the egg into the area just below the bark, resulting in spiral tunnels that can girdle the stem. The grubs then tunnel into the pith, eventually turning and burrowing upward. This damage leads to wilting of the canes beyond that point. The hollow stem weakens the cane, causing the stem to break. This damage over several years can weaken and kill plants. Damage to the floricanes often results in stem galls and reduced fruit production.

Biology and life cycle The rose stem girdler has a single generation in a year. Adults mate and lay eggs in June and July, with larvae feeding through the summer and overwintering in the cane as a mature larva. When temperatures reach 55°F the insect pupates, and adults emerge in May and June.

Pest Monitoring When moving through the fields or garden, watch for canes on roses and blackberries that have galls or spiral swellings of the bark, or wilted and/or broken stems. In June, watch for adults feeding on leaves or beat foliage using a beating sheet to capture adults.

Management—cultural control

Through winter and spring, before adults emerge in May or June, remove and destroy galled, swollen, wilted or broken canes well below the damaged area to remove larvae and pupae. Larvae can continue to develop even in broken stems on the ground.

Management—chemical control

See “Wood or Trunk Borers” in Table 4:

For further information:

Alston, D. 2015. Rose stem girdler. Utah State University Extension. Utah Pests fact sheet ENT-178-15. https://extension.usu.edu/productionhort/files-ou/RoseStemGirdler.pdf

Westcott, R.L., C. Looney, M. Asche. 2015. Agrilus cuprescens (Ménétries) (Coleoptera: Buprestidae), the rose stem girdler, discovered in the State of Washington, with comments on host plant associations. The Coleopterists Bulletin 69(2): 275-279. (https://bioone.org/journals/the-coleopterists-bulletin/volume-69/issue-2...)