There are two species of rose chafers in the genus Macrodactylus in North America. The most common in eastern United States is the rose chafer, Macrodactylus subspinosus (Fabricius) and is found from eastern Canada south to Colorado. The second species is the western rose chafer, Macrodactylus uniformis Horn and it occurs in Arizona, New Mexico, Texas and south into central Mexico. Both species are very similar in size, body shape, and habits. Control measures for one species should also apply to the other.
The rose chafer, Macrodactylus subspinosus (Fabricius), is a tan, long-legged slender beetle from 8-12 mm long. The rose chafers damage plants by feeding on the flowers, newly set fruit and foliage. On roses it skeletonizes the leaves in the same way as other scarab beetles like the Japanese beetle, Chinese rose beetle, and the serica garden beetle. It feeds on on the foliage of many different plants and it is greatly attracted by flowers. On June 27, 1997 I observed numerous beetles on milkweed flowers in an area near Galesville, WI. I also swept this beetle from the blooms and foliage of several plants in the area. The rose chafer is native to the northeast from eastern Canada south to Colorado.I have seen samples from Fenton, MI and Galesville, WI.
LIFE CYCLE: Adult beetles emerge from the soil in late May through early June and and they live for about one month. Mating occurs soon after emergence and the females lays her 24-36 eggs continuoulsy for about two weeks in the soil in grassy sandy areas. Upon hatching the larvae burrow in the soil and feed on the roots of grasses and weeds. The overwinter as a larvae and continues development in the spring. The full grown larva or grub is white and measures up to 18 mm in length. Pupation occurs in the spring. The rose chafer has only one generation per year.
CONTROL: Scouting or monitoring for the presence of rose chafers is very important for adequate control. Rose chafers are most prevalent in areas with sandy soil. Adults readily attracted to many types of flowers and feed on the foliage many plants. The larvae or white grubs feed on the roots of grasses and many cultivated and wild plants. From late May through July, the foliage should be inspected for skeletonized leaves and the presence of adult beetles on the leaves and flowers.
Rose chafers can be handpicked and destroyed if the infestations are light. Rose chafers can be very numerous especially in areas with sandy soils. In these cases insecticides may not give satisfactory control as rose chafers can move in from surrounding untreated areas or the insecticides do not seem to prevent feeding activity for very long. However, after about 2-3 weeks of heavy damage the beetle numbers appear to subside. Insecticides used in the control of rose chafers include carbaryl (Sevin), acephate (Orthene), diazinon, and chlorpyrifos (Dursban), Tempo, Talstar, Mavrik, rotenone, etc.
It was interesting to read that birds sometimes die from eating adult rose chafers. The beetles apparently have a chemical that affects the heart of small, warm-blooded animals.
The western rose chafer, Macrodactylus uniformis Horn occurs primarily in Arizona and New Mexico south into Mexico. It resembles the rose chafer and its damage is similar. It is 10mm long and the body is rather slender, long-legged, and yellowish brown in color. Its pubescence is longer and denser than that of the rose chafer. I have collected numerous beetles in southern Arizona and central Mexico feeding on many kinds of plants.
Essig, E. O. 1926. Insects of Western North America. The MacMillan Company, NY, p. 445.
Johnson, Warren T. and Howard H. Lyon. 1988. Insects that Feed on Trees and Shrubs, 2nd edition, Cornell University Press, Ithaca, NY., pp. 236-37.
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