Apidae

Tribe Bombini (seven taxa)

Genus Bombus, seven taxa

    According to Milliron, B. fervidus does not occur in Florida. Identifications of males of this species are likely to be B. pensylvanicus. Mitchell also notes this common mistake. I have not seen any definite specimens of B. fervidus from Florida. Mitchell also lists B. terricola from Florida but no specimens have been seen to confirm this. Milliron’s map shows B. terricola to extend southward to about North Georgia along the higher elevations of the Appalachian mountains. It is unlikely that this species occurs in Florida. B. affinis is also found in a similar distribution but does not likely extend into Florida. Thus, this key does not include these 3 species. From personal experience collecting in both South Florida (Everglades National Park) and North Florida (Tall Timbers in Leon County, St. Marks Wildlife Refuge in Wakulla County, and Osceola National Forest in Baker and Columbia counties, Bombus impatiens, Bombus pensylvanicus, and Bombus fraternus are the three most common species. Bombus griseocollis, B. bimaculatus and Bombus nevadensis auricormis appear to be rarer. Bombus variabilis was classified as Psithyrus variabilis in Mitchell's book. Recent phylogenetic studies place this group of parasitic bees within the Bombus lineage (Michener 2000).

Keys to Queens, Workers, and Males (from Mitchell 1962)

1. Hind tibiae with well developed corbiculae…..2



Hind tibiae relatively slender, rather uniformly pubescent throughout….Subgenus Psithyrus, Bombus variabilis (these are the females in this group, no workers present)

2. Laterall ocelli distinctly below supraorbital line….3



Laterall ocelli located at or near level of supraorbital line….5



3. Malar space longer than width of mandible at base…Subgenus Bombias, Bombus nevadensis auricormis

Malar space shorter than width at base of mandibles….Subgenus Pyrobombus, 4



4. Dorsum of thorax without an interalar black band, usually with a very small median area of black pubescence…Bombus griseocollis



Dorsum of thorax usually with a conspicuous, transverse band of black pubescence between the wing bases…Bombus fraternus



5. Posterior half of scutum and all of scutellum black pubescent, Subgenus Megabombus, Bombus pensylvanicus pensylvanicus>

Posterior portion of dorsum of thorax with some yellow pubescence…Subgenus Bombus, 6



6. Tergum 2 of abdomen entirely black pubescent…Bombus impatiens

Tergum 2 of abdomen largely black pubescent, with a limited amount of yellow medially at base…Bombus bimaculatus

1. Hind tibiae with well developed corbiculae…..2



Hind tibiae relatively slender, rather uniformly pubescent throughout….Subgenus Psithyrus, Bombus variabilis (there are no true workers in this group, females show no disinct size differences between queens and workers)

2. Laterall ocelli distinctly below supraorbital line….3



Laterall ocelli located at or near level of supraorbital line….5



3. Malar space fully equal in length to basal width of mandible; scutellum black pubescent…Subgenus Bombias, Bombus nevadensis auricormis

Malar space much shorter than basal width of mandible; scutum or tergum 3 with black pubescence…4



4. Dorsum of thorax with a distinct interalar black band; tergum 2 entirely covered with yellow pubescence.. Bombus fraternus



Dorsum of thorax with no interalar band; tergum 2 narrowly black on apical margin, otherwise yellow, slightly tinged with brown..Bombus griseocollis



5. Posterior half of scutum and all of scutellum black pubescent, Subgenus Megabombus, Bombus pensylvanicus pensylvanicus



Scutellum largely or entirely yellow pubescent…Subgenus Bombus, 6



6. Abdominal terga 2 to 6 entirely black pubescent, with only tergum 1 yellow; malar space shorter than basal width of mandible…Bombus impatiens

Abdominal tergum 2 largely black pubescent, but invaded by yellow along basal margin medially; malar space fully equal to width of mandible at base…Bombus bimaculatus

1. Hind tibiae convex, quite densely pubescent on outer surface, gonostylus more elongate, much exceeding apex of gonocoxites…Subgenus Psithyrus, Bombus variabilis



Hind tibiae somewhat flattened, rather sparsely pubescent on outer surface; gonostylus of genital armature very short, not much exceeding apex of gonocoxite…2



2. Eyes usually converging above, the lateral ocelli nearer to margins of the eyes than to each other; malar space very short, length one-fourth or less the basal width of the mandible….3



Eyes about parallel, the lateral ocelli distant from eye margin; malar space nearly or quite as long as basal width of mandible….5



3. Malar space exceedingly short, almost obliterated, eyes nearly touching base of mandibles, strongly convergent above…Bombus fraternus

 

Malar space distinct, even though short, eyes somewhat removed from base of mandibles…4



4. Eyes nearly parallel, even though face very narrow, with ocelli nearer margin of vertex than to antennae…Bombus griseocollis

 

Eyes strongly convergent above, ocelli located midway between antennae and hind margin of vertex…Bombus nevadensis auricormis

5. Malar space not much longer than wide, about a fourth the length of the eye; abdominal tergum 5 usually black pubescent (many specimens from Florida have yellow pubescence, though!)..Bombus pensylvanicus pensylvanicus



Malar space considerably longer than wide, about one third of the length of the eye; tergum yellow pubescent…Sugenus Bombus, 6



6. Segment 2 of abdomen entirely black pubescent; malar space shorter than width of mandible at base..Bombus impatiens

Segment 2 of abdomen with at least some yellow pubescence; malar space longer than width of mandible at base…Bombus bimaculatus

Subgenus Megabombus, 1 taxa

Apidae: Bombus pensylvanicus pensylvanicus De G.

County Records: Alachua, Broward, Charlotte, Citrus, Collier, Miami-Dade (From Milliron); Baker, Columbia, Leon, Wakulla (Pascarella unpub. data).

Locations: Altamonte, Bonita Springs, Crystal River, Everglades, Ft. Lauderdale, Gainesville, Homestead, Pinecrest, Punta Gorda (from Milliron)

Dates: Mid-February to late November

Plants: polylectic

Notes: One of the most common species. Extends all the way to the tip of the peninsula. Unknown from the keys. Probably occurs throughout Florida.

Queen:

Worker:

Male:

Subgenus Bombias Robertson

Apidae: Bombus nevadensis auricormis Robertson

County Records: None from the FSCA. Milliron’s map shows it occurring throughout Florida

Locations:

Dates:

Plants: polylectic

Notes: Specimens of this species have not been seen. No photos are available at this time. Perhaps it has been confused with other species?

Subgenus Bombus, 2 taxa

Apidae: Bombus impatiens Cresson

County Records: Baker, Columbia, Leon, Miami-Dade (rare), Wakulla

Locations:

Dates: January-November

Plants: polylectic

Notes: The map above is surprising given the abundance of this common species. It likely occurs throughout Florida.

Queen:

Worker:

Male: 

Apidae: Bombus bimaculatus Cresson

County Records: Alachua, Baker, Clay, Franklin, Lake, Levy, Highlands, Okaloosa, Wakulla

Locations:

Dates: Feb.-September

Plants: polylectic

Notes: This species might be limited to the panhandle and southward to the central peninsula. 

Queen:

Worker:

Male:

Subgenus Pyrobombus, species group Cullumanobombus Vogt.; 2 taxa

Apidae: Bombus fraternus Smith

County Records: Alachua, Gadsden, Levy, Liberty, Orange, St. John, Volusia

Locations: Altamonte, Glen St. Mary, Orlando (add counties), Gainesville, Vilano Beach, Wewahitchka,

Dates: Queens: April; Workers: June-August; Males August-October

Plants: polylectic

Notes: This species might be limited to the panhandle and northern peninsula based on the map above.

Queen:

Worker:

Male:

Apidae: Bombus griseocollis De G.

County Records: Alachua, Broward, Highlands

Locations: Lake Placid. Everglades, Palatka, Pinecrest

Dates: March-October; Queens: November, April; Workers: April-June; Males: April in Florida; this species may be active during the winter months in southern Florida.

Plants: polylectic

Notes: Probably occurs throughout Florida but never in great numbers.

Queen:

Worker:

Male: 

Subgenus Psithyrus, one taxon

Apidae: Bombus variabilis Cresson

County Records: Leon, Miami-Dade

Locations:

Dates: In Miami-Dade County, specimens were collected January-April, and then again in November and December. In Leon County, all specimens were collected in October.

Plants: polylectic, forages solely for nectar

Notes: probably throughout the state although collections are only known from Miami-Dade and Leon; Parasite on Bombus species.