Akre, R.D., A. Greene, J.F. MacDonald, P.J. Landholt, and H.G. Davis. (1981). Yellowjackets of North America, North of Mexico. U.S. Department of Agriculture, Washington, D.C. Handbook #552. |
Vespula squamosa (southern yellowjacket) is widely distributed from Iowa to Texas and across to the eastern seaboard, and occurs in the southeastern part of the Transition, Upper Austral, and Lower Austral Zones of the Nearctic Region (fig. 52), and also in southern Mexico and Guatemala. Nesting biology was studied by MacDonald and Matthews (1975, 198_b).
Easily recognized by its color pattern and extreme female caste dimorphism, V. squamosa is an intriguing species. Unassociated until the early 1900’s when a colony was excavated, the very large and predominately orange queen differs markedly from the worker and male, which are more typical of yellowjackets in size and color. Also curious is the success of V. squamosa in the southern distribution of Nearctic Vespula. Since the discovery of a V. squamosa queen in the nest of V. vidua (Taylor, 1939), V. squamosa has been considered a facultative social parasite of Vespula.
Working in Georgia, MacDonald and Matthews (1975) found V squamosa to be a facultative social parasite of V. maculifrons, a member of the V. vulgaris group. The parasite queen usurps the nest from the host queen and assumes complete control of the colony. Host workers rear the first brood of V. squamosa workers and eventually a colony consisting solely of V. squamosa results. The relationship appears to be facultative since about 20 percent of mature V. squamosa colonies exhibit no evidence of a V. maculifrons heritage. The remaining 80 percent either contain host workers (early in the season) or the nests have clearly visible remnants of V. maculifrons nest construction. The incipient host nest with much smaller, tan cells is in striking contrast to the surrounding larger, gray cells constructed by parasite workers; thus, although host workers may not be present, the early history of a V squamosa colony can be determined by analyzing nest architecture.
The above account depicts the host-parasite relationship in Georgia. In other areas, a different host species may be involved, and the percentage of nests parasitized probably varies considerably. Accordingly, discussion of the nesting biology of V squamosa must take into account the requirements of host species.
Most V. squamosa colonies (usurped or pure) are located in disturbed habitats, particularly in yards, parks and roadsides, whereas a few are in “natural” habitats. Among the latter, nearly all colonies are in pine forests, a few are in mixed forests but rarely in hardwoods despite the abundance of V. maculifrons colonies.
Coincident with its host, V. squamosa nests typically are subterranean (MacDonald and Matthews, 1975, 198_b; Miller, 1961); however, aerial nests have been reported (Tissot and Robinson, 1954), and in the Washington, D.C., area where V. maculifrons commonly nests in house walls, V. squamosa colonies are also frequently observed in these locations. Colonies typically persist into autumn with most producing reproductives from late August into November; this seems intermediate between the longer cycle of the V. vulgaris group and the shorter cycle of the V. rufa group. Colony size is variable but most contain 500 to 4,000 workers at their peak and ultimately construct a nest of 2,500 to 10,000 cells (table 6).
Sometimes, perennial colonies of this species persist in subtropical areas of its distribution. For example, Tissot and Robinson (1954) recorded a nest of V. squamosa of 6 ft by 30 inches by 12 inches with 17 combs, and another was 9 ft tall with a circumference of 9 ft 10 inches and contained 39 combs. A perennial, subterranean colony located 13 miles west northwest of Gainesville, Fla., was killed in early February 1977 (J. Sharp, USDA, SEA, Gainesville). The nest had 14 comb levels and 120,130 cells (fig. 53 a, b); at least 1,350 of these cells were reproductive cells, although a complete count could not be made because of the nest’s poor condition.
Although the behavior of V. squamosa has not been studied, some of the workers definitely scavenge for protein (R. Matthews, Univ. of Ga., personal commun.) and may be a nuisance at picnics. This behavior is not typical for V. rufa group species.
V. squamosa is an important pest species because of the great number of nests found in urban and recreational areas. Colonies are typically large and disturbances of the nests usually result in multiple stings.
Reprinted with permission from: Miller, C.D.F. 1961 Taxonomy and Distribution of Nearctic Vespula. The Canadian Entomologist Supplement 22.
Color.—Queen, orange with black markings. Male and worker, black with
Structure.—Malar space less than half as long as the penultimate antennal segment (Fig. 1); occipital carina incomplete (Fig. 4); posterior side of second cubital cell of forewing equal to or slightly longer than that of third cubital cell (Fig. 9); male genitalia as in Fig. 17.
Abdominal Color Patterns.—as in Figs. 49, 52, 55.
Facial Color Pattern.—as in Fig. 78.
This Nearctic species is widely distributed in the southeastern part of the
Transition, Upper Austral and Lower Austral zones of the Austral region of
One has little difficulty in recognizing this species which is distinct over most of its range. An intraspecific variant which seems to be geographically definable has been located in the mountains of southern Mexico. The amount of material available for the study of this variant is so little that to make a conclusion on its genetic value to the V. squamosa population would be pure speculation. It appears to be a melanistic form which could be the result of climatic conditions in the area in which it has been found. Bequaert called this a subspecies of V. squamosa. The author treats it as a variant of this species not worthy of nomenclatorial recognition.
Ecological Notes.—The nest of this species was considered to be terrestrial until Tissot and Robinson (1954) proved it to be aerial as well. A study of the nesting habits of this species over its entire range may prove to be an interesting thesis.
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Updated: 2018-07-15 23:47:54 gmt