Vol. 94, No. 4, September & October, 1983 147 INSECTS VISITING FLOWERS OF WILD RED RASPBERRY IN SPRUCE-FIR FORESTED AREAS OF EASTERN MAINE 1 Richard W. Hansen, Eben A. Osgood^ ABSTRACT: Flower-visiting insects were collected from wild red raspberry ( Rubus idaeus L. ) flowers in spruce-fir forested areas of eastern Maine in 1981. Collections included 5 insect orders and 49 families. At least 38 species of Syrphidae, including 2 new species, and 47 species of Apoidea were represented. The most commonly collected visitors were Dialictus spp. bees and Syrphidae. Native Apoidea are probably the primary pollinators of R. idaeus in Maine, though some of the more pubescent Coleoptera and Diptera, particularly the syrphids probably have a pollinating function. Red raspberry, Rubus idaeus L.3, is a common shrub in Maine, growing in a variety of well-exposed situations. It is especially common in cuttings or natural openings in forested areas. It produces biennial canes that reach 2 m in height, from a perennial rootstock (Fernald 1950); only the second year canes produce flowers. Raspberry flowers are borne singly or in small clusters on the terminal portions of the floricane. The flowers are about 1 cm in diameter, with numerous stamens and pistils, creamy-white petals, and conspicuous bristly sepals. The fleshy fruit is typically red in color. Although the reproductive methods of the genus Rubus are not fully understood, it appears that raspberry flowers are largely self-sterile, and insect pollination is necessary for normal fruit development (Jensen and Hall 1979, McGregor 1976). Honeybees are the dominant pollinators of raspberries in agricultural situations (McGregor 1976) and because of the copious production of nectar and pollen, raspberry bloom is considered to be prime bee forage (Howes 1946). Besides the economic value of commercial raspberries in fruit and honey production, wild raspberries, such as R. idaeus, provide important wildlife food (Gill and Healy 1974). Honeybees, Apis mellifera L., are rare or absent throughout Maine's spruce-fir forest, so other insects are necessary for pollination and fruit set of wild raspberry. Raspberry flowers are accessible to many types of insect visitors (Faegri and van der Fiji 1971), and this factor, coupled with the high level of nectar and pollen production and wide distribution of R. idaeus, should ensure that a varied insect fauna visits the bloom. 1 Received March 17, 1983. Accepted May 20, 1983. ^Research Associate and Professor, Department of Entomology, University of Maine, Orono, ME 04469 ^Several varieties of R. idaeus L. can be found in Miane; var. strigosus (Michx.) Maxim, is probably the variety encountered in this study (Fay Hyland, pers. comm., Femald 1950). ENT. NEWS 94(4):' 147-151. September & October. 1983
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