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HYMENOPTERA 699
There are generally three castes; queens or fertile females, workers or sterile
females, and drones or males. The males are the product of unfertilized eggs;
the queens are fed more and are larger than the workers. Workers may produce
eggs which hatch only into males but are incapable of fertilization. The enveloped
paper nests are often very l!irge and may be suspended from trees
and various other objects or constructed in large holes excavated in the
ground. The queen starts the nest in the spring, using wood fiber which is
reduced to paper by mastication. When a few cells are completed, a fertile
egg is laid in each. The legless white grubs soon appear and are fed daily
on insect material and sweets. When the larvre are mature, the cells are
capped and pupation follows therein. Workers only are produced until
fall, when the sexes appear and mating occurs. The young queens hibernate
and establish new colonies the following spring. The adults feed on various
insects, meats, fruits, honeydew, and other sweets, and are often very
troublesome about fruit canneries and drying sheds, and also do considerable
damage to fresh fruits. This damage is partially offset by the destruction of
great numbers of houseflies, stablefiies, and other flies, caterpillars, and similar
injurious insects. Duncan (1939) has made a splendid contribution to the
biology and morphology of the North American vespine wasps.
These common wasps may be separated into three genera according to the
width of the malar-ocular spaces and nesting habits as follows:
Malar-ocular spaces either very narrow or absent; nesting above
ground, nests suspended from trees and bushes
Dolichovespula (Rohwer)
Malar-ocular spaces well defined; large species nesting above ground
in hollow trees, stumps, caves, sheds. . . • . . . Vespa Linn.
Malar-ocular spaces very broad; nesting underground
Vespula Thomson
Species belonging to the genus Dolichovespula (Rohwer) (erected as a subgenus
of Vespula by Rohwer) include the common European D. silvestris
(Scopoli) and D. media (DeGeer); the European and North American D.
norwegica (Fab.); the North American D. arenaria (Fab.); and the bald-faced
hornet, D. maculata (Linn.), and D. adulterina (du Buysson), an inquiline in the
nests of D. arenaria var. fernaldi (Lewis).
The outstanding representative of the genus Vespa Linn. is the giant hornet,
V. crabo Linn., a European species thought to have been introduced and established
in the United States between 1840 and 1854. It was first taken in the
United States in 1854. It now occurs in parts of Connecticut, New York, New
Jersey, Pennsylvania, Delaware, and Maryland.
Species belonging to Vespula Thomson include the well-known European
V. vulgaris (Linn.); the widely distributed Holarctic V. austriaca (Panzer),
which lives as an inquiline in the underground nests of V. rUfa (Linn.); the
European and North American V. germanica (Fab.) and V. rufa (Linn.); and
the North American V. maculifrons (du Buysson), V. pennsylvanica (Saussure),
V. squamosa (Drury), and V. sulphurea (Saussure).