1 The vertex, the area of the head behind the ocelli, is large. A large (>20 mm) brown and yellow species.....Vespa crabro
1' The vertex is small; the head extends little behind the rear ocelli. The wasp is either black with yellow or black with white.....2
[If the wasp has a large vertex but is not a large, brown and yellow species, it may not be in the subfamily Vespinae. Click here to help determine if it is in this subfamily.]
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2 (1') The bottom edge of the compound eye is almost touching the base of the mandibles (Genus Vespula).....6
2' The bottom of the eye is farther from the base of the mandibles, about as long or longer than the second to last antennal segment. (Genus Dolichovespula).....3
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3 (2') The wasp is black with white markings.....4
3' The wasp is black with yellow markings..... 5
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4 (3) The first three gastral terga are all black. A large common species (>15 mm).....D. maculata
4' The first three gastral terga are with white markings. A social parasite of D. arenaria and D. norvegicoides. A smaller, less common, species.....D. arctica
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5 (3') The genal area is nearly continuos yellow, not broken by black. The rear edge of the first and second gastral terga are not continuous yellow, they are broken by black medially......D. arenaria
5' The genal area is usually widely interupted by a band of black. The rear edge of the first and second gastral terga are continuous yellow, not broken by black. A less common species.....D. norvegicoides
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6 (2) The wasp is black with white markings.....V. consobrina
6' The wasp is black with yellow markings.....7
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7 (6') Each compound eye of the wasp is completely surrounded by a yellow ring. A common species. (This character also works for queens).....V. pensylvanica
7' The compund eye is not surrounded by a yellow ring..... 8
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8 (7') The top side of the thorax is black with two prominent longitudinal yellow lines near the center. (California, Southern Oregon, New Mexico, and Arizona)..... V. sulphurea
8' The upperside of the thorax is without two parallel yellow lines..... 9
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9 (8') The scape, is yellow underneath..... 10
9' The scape, is black underneath..... 11
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10 (9) The genal area is usually continuous yellow, sometimes narrowly broken by black. Rear middle area of black region of Gastral tergum 2 pointed..... V. atropilosa
10' The genal area is broken by black, rarely continuous yellow. Rear middle region of the black area of Gastral tergum 2 rounded...... V. acadica
[V. austriaca, a parasitic species, keys out to this couplet.]
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11 (9') The genal area is continuous yellow, usually not broken by black. Gastral tergum 2 usually with free, or nearly free, black spots (In some melanic morphs, there are no free black spots)..... V. germanica
11' The genal area is broken by black, sometimes narrowly. Gastral tergum 2 without free black spots..... V. vulgaris
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Page author: Matthew P. Kweskin kweskm@evergreen.edu
Last modified: 2 Feb 1997