The Rose Chafer (Macrodactylus subspinosus (Fabricius)), is a mostly tan-colored scarab beetle about 1/3 to 1/2-inch in length, with long, spiny, reddish-brown legs. In addition to roses, the adult beetles feed on a great variety of other flowers, trees and shrubs, including many plants of agricultural importance. This includes fruits such as strawberries, raspberries, blueberries, peaches, grapes, and cherries, as well as some vegetable crops such as corn, beans and peppers. There is only a single generation per year, and the adults begin emerging from the ground in northeastern North America around the end of May or early June, typically a few weeks before Japanese beetles begin to do the same. They overwinter in the ground in the larval/grub stage (one of several C-shaped ‘white grubs’ found in this part of the world), and pupate in the spring. The grubs feed on the roots of grasses and non-crop plants. They do not cause damage to home lawns or landscape plants.
Areas with sandy soils tend to see the highest populations of grubs and emerging adults, but since the adults are strong fliers, the beetles themselves can be found in many different habitat types throughout a given region. Thus, new beetles can fly in from surrounding areas, making control efforts challenging at times. Individual beetles live for about three weeks. Mating occurs soon after emergence, and the females lay their eggs in the soil (mostly sandy soils).
Eating these beetles can be deadly to small animals and birds, including chickens, because of a toxin the beetles have in them that acts upon the heart.
Additional Information and Photos:
- Rose Chafers (University of Minnesota Extension)
- Rose chafer management for vineyards (Michigan State University)
- Integrated Pest Management of Roses (Cornell University) — Management tip: Hand pick adult Rose Chafers and/or Japanese Beetles and drop them into a jar of soapy water; Individual flowers for show can be protected with covers (bags).
- Additional Rose Chafer Photos (BugGuide.net)