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Giant Resin Bee
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*Wyatt Mangum & S. Bambara, Extension Entomologist

CAUTION: This information was developed for North Carolina and may not apply elsewhere.


Giant Resin Bee (Megachile sculpturalis Smith)

picture of giant resin bee resting on someone's fingerThe giant resin bee (Megachile sculpturalis Smith) is a solitary Asian bee that has been introduced into the southeastern United States. Exactly how is not known, but it is assumed that the introduction was a result of commerce and occurred within the last few years. It was first reported in North Carolina in June, 1994 and is now known in most of the southeastern states.

Biology

These bees are large and quite impressive. They have a cylindrical body ranging from 1/2 to almost one inch (14 - 24 mm) in length, which is longer than most other bees in North America. The females tend to be larger than the males. The head and abdomen of the giant resin bee are black. Dense yellowish-brown hairs cover its thorax. Their wings are dark, but still transparent.

Giant resin bees usually hold their wings in a "V" position over the top of the body when foraging on flowers. They also have large jaws, which the females use for carrying nest material. People usually encounter giant resin bees around buildings and wooden decks, because they commonly nest in vacant carpenter bee tunnels.

These bees will also nest in small spaces between the boards of a building and in dry rotten logs with tunnels bored by other insects. Smaller females can also nest in the holes of a blue orchard bee (Osmia lignaria) wooden nesting block. Even though giant resin bees have large jaws, their jaws are not designed to drill into wood. Therefore, though nesting in buildings, these bees are not causing damage. At this time, it is unknown how the giant resin bee may affect native bee populations.

Life History

The female bee nests alone and begins by preparing a cell in an existing tube or narrow cavity, using resin and sap collected from trees. Other materials such as bits of rotten wood and mud are also used in nest construction. Next she collects pollen and carries it to the nest on the underside of her hairy abdomen.

After completing several pollen collecting trips, she lays an egg on the pollen ball in the cell. Then she seals it, and prepares another cell. Continuing in this fashion, one female can complete about 10 cells. If the entrance of the nesting tube is directly exposed to the outside, the tube may be noticeably sealed with a resin, wood and sometimes mud cap. After the eggs hatch, the larvae feed on the pollen and spend the winter within their cells. The larvae pupate in late spring and the adult bees emerge that summer.

picture of giant resin bee on flowerIn North Carolina, giant resin bees are most active from June to September. They collect nectar and pollen from a variety of plants including goldenrain tree (Koelreuteria paniculata), waxleaf privet (Ligustrum lucidum), and vitex. Although the bees are solitary nesters, several may nest near each other. Nesting females also attract male bees, which may be seen hovering near the nest sites. When these large bees fly near a building, they may seem threatening, however, they are essentially harmless.

Even when disturbed at the nest, the female bee is not defensive or prone to sting. She flies away and returns to the nest later. The female bee can sting, but she rarely does so unless confined in your hand. The male bee cannot sting.

Control

Since these bees are opportunistic and nest in existing wooden cavities, rather than excavating their own, they are not damaging wood or buildings. They sometime occupy carpenter bee holes and might be confused with carpenter bees.  Stings are also unlikely. Therefore, control measures would generally seem unnecessary.

Additional information:

Mangum, W. A. & R. W. Brooks. 1997. First Records of Megachile (Callomegachile) sculpturalis Smith (Hymenoptera:Megachilidae) in the Continental US. Jour. Kans. Ent. Soc. 70(2). pp. 140-142.

Mangum, W.A. & S. Sumner. 2003. A Survey of the North American Range of Megachile (Callomegachile) sculpturalis, an Adventive Species in North America. Jour. Kans. Ent. Soc. 76(4), 2003, pp.658-662.  


Other Resources


Published by North Carolina Cooperative Extension Service

Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914. Employment and program opportunities are offered to all people regardless of race, color, national origin, sex, age, or disability. North Carolina State University at Raleigh, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.

*Prepared by Wyatt Mangum, Mathematics Dept., University of Mary Washington, Fredericksburg, VA & S. Bambara, Extension Entomologist, NCSU

ENT/ORT-110 Feb. 1998
Web page last reviewed January, 2011 by the webperson.