The Bumble Bees of Florida, Bombus spp.1
Introduction
Bumble bees are large, social bees which produce annual colonies. Mated queens overwinter in the soil and emerge from hibernation in early spring when they feed on spring flowers and search for a suitable location, such as a former rodent nest in the soil, to begin their colonies.
Adult bumble bee, Bombus sp.
Once a nest site is found, the queen collects pollen and lays her first brood of worker eggs. Workers emerge about 21 days after the eggs are laid and take over the duties of pollen and nectar collection as well as colony defense. The size of the workers increases with each new brood. The third caste of bumble bees, the males, are usually produced in midsummer.
Bumble bees are easily recognized by the corbicula or pollen basket on the hind tibiae in the females. Honey bees are the only other bees in Florida with this structure, but are easily recognized by their smaller size, hairy eyes, and lack of hind tibial spurs.
The five species of bumble bees found in Florida are usually separated by the pattern of the black and yellow pubescence. The closely related parasitic Psithyrus spp. are easily distinguished by the lack of the corbicula.
All bumble bees found in Florida range north into Canada (Laverty & Harder 1988). Bumble bees become rarer in southern Florida. None are known from the Keys. Two species (Bombus griseocollis and B. pennsylvanicus) are known from Collier County whereas a third species (B. impatiens) has been collected in West Palm County. These are beneficial insects which pollinate many native and ornamental plants. They can sting severely, so problem nests near human dwellings should be removed by experienced pest control operators.
Figures of Florida Bombus spp. 1. fraternus; 2. pennsylvanicus; 3. impatiens; 4. griseocollis; 5. bimaculatus; 6. griseocollis; 7. bimaculatus.
Key To The Bumble Bees
1. Antenna with 12 segments; abdomen with six visible terga; tip of abdomen pointed, with stinger; corbiculae on hind tibiae (not Psithyrus); active all summer; females (queens & workers) ..... 2
1'. Antenna with 13 segmenta; abdomen with seven visible terga; tip of abdomen round, no stinger; hind tibia lack corbiculae; active from middle of summer till winter; males ..... 7
2. Hind tibia relatively slender, without corbicula; parasitic forms ..... Psithyrus variabilis
2'. Hind tibia with well developed corbicula (Bombus spp.) ..... 3
3. Posterior half of scutum and all of scutellum with black pubescence (Figure 2) pennsylvanicus
3'. Posterior half of scutum and scutellum with some yellow pubescence ..... 4
4. Dorsum of thorax with a conspicuous, transverse band of black pubescence between wing bases (Figure 1) ..... fraternus
4'. Dorsum of thorax without transverse black band between wing bases ..... 5
5. Tergum II of abdomen entirely black (Figure 3) ..... impatiens
5'. Tergum II of abdomen with yellow pubescence medially at base (Figure 4 and Figure 5) ..... 6
6. Lateral ocellus distinctly below supraorbital line (Figure 6) ..... griseocollis
6'. Lateral ocellus at level of supraorbital line (Figure 7) ..... bimaculatus
7. Hind tibia convex, densely pubescent on outer surface; gonostylus much exceeding apex of gonocoxites; parasitic forms ..... Psithyrus variabilis
7'. Hind tibia somewhat flattened, sparsely pubescent on outer surface; gonostylus not much exceeding apex of gonocoxite (Bombus spp.) ..... 8
8. Eyes usually converging above, lateral ocelli nearer margins of eyes than to each other; malar space no more than 1/4 basal width of mandible ..... 9
8'. Eyes about parallel, lateral ocelli closer to each other than to eye margins; malar space about as long as basal width of mandible ..... 10
9. Malar space nearly obliterated; eye nearly touching base of mandible ..... fraternus
9'. Malar space distinct; eye somewhat removed from base of mandible ..... griseocollis
10. Dorsum of thorax with a median band of black pubescence ..... pennsylvanicus
10'. Dorsum of thorax entirely yellow pubescent or with median patch of black hairs that don't reach tegulae ..... 11
11. Segment two of abdomen entire black pubescent ..... impatiens
11'. Segment two of abdomen with at least some yellow pubescence ..... bimaculatus
List of Species
Bombus bimaculatus Cresson 1863. County Records: Alachua; Clay; Franklin; Highlands; Lake; Levy; Marion, Okaloosa Orange.
Bombus fraternus (Smith) 1854. County Records: Alachua; Franklin; Gadsden; Levy; Liberty; Orange; St. Johns.
Bombus griseocollis (DeGeer) 1773. County Records: Alachua; Clay; Collier; Highlands; Marion; Osceola.
Bombus impatiens Cresson 1863. County Records: Alachua; Bradford; Calhoun; Escambia; Franklin; Jackson; Gadsden; Highlands; Levy; Liberty; Okaloosa; Orange; Palm Beach; Polk; Santa Rosa.
Bombus pennsylvanicus (DeGeer) 1773. County Records: Alachua; Bradford; Collier; Escambia; Flagler; Highlands; Lake; Lee; Levy; Marion; Orange; Putnam; Sarasota; Santa Rosa.
Bombus terricola Kirby 1837. No specimens seen from Florida but recorded from Florida by Mitchell (1962).
Selected References
Koehler, P.G., D.E.Short and T.R. Fasulo. (1998). Pests In and Around the Home. UF/IFAS, CD-ROM.
Mitchell, T.B. 1962. Bees of the Eastern United States. Volume II. Technical Bulletin No. 152, North Carolina Agricultural Experiment Station, pp. 1-557.
Laverty, T.M. and L.D. Harder. 1988. The bumble bees of Eastern Canada. Canadian Entomologist 120: 965-987.
Morse, D.H. 1982. Behavior and ecology of bumble bees, pp. 245-322 . In Hermann, H.R. (Ed.) Social Insects, Vol. 3. Academic Press, New York & London.
Footnotes
This document is EENY-050, one of a series of the Entomology and Nematology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date August 1998. Reviewed March 2008. This document is also available as a Featured Creature at http://creatures.ifas.ufl.edu/. Please visit the EDIS Web site at http://edis.ifas.ufl.edu.
Lionel A. Stange, Florida Dept. of Agriculture & Consumer Services, Division of Plant Industry, Gainesville. Originally published as DPI Entomology Circular No. 353.
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