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[Vol. 89 
make these appendages a formidable, offensive weapon, probably as 
effective as the sting during colony invasions (Reed 1982). Indeed, 
Weyrauch (1937) concluded that the powerful mandibles of vespine 
inquilines were adapted for fighting with the host. 
Another adaptation for combat with host queens and defending 
workers is the enlarged femora of the front legs. The only reference 
to this feature is found in the original description of Vespa arborea 
Smith (= V austriaca) (cited in Robson 1898) in which he stated 
that the legs of this species were “stouter and longer” than in V rufa. 
The robust front legs are not only an advantage during colony 
invasion, but also are likely an adaptation for the frequent mauling 
and grabbing of host workers which occurs during early occupation 
of the colony (Reed 1982). 
The sting is greatly curved in vespine inquilines presumably to 
facilitate penetration between the vulnerable intersegmental mem- 
branes of defending colony members. The sharp downward bend of 
the seventh sternum, likely an accommodation for the recurved 
sting, was also noted by Bischoff (1931). The abrupt curve at the 
distal tip of the stylet in the inquilines, as well as in V. squamosa, 
would appear to impede the thrusting of the two lancets. However, 
the distal end may be curved to hook a sclerite and thus enlarge the 
intersegmental membrane for further penetration by both the stylet 
and lancets. 
There is no obvious glandular degeneration in V austriaca, but a 
hypertrophy of one exocrine gland exists. Evidently this enlarge- 
ment of the Dufour’s gland has some role in vespine social parasit- 
ism, but unfortunately the function in any vespine is still unknown 
(Landolt and Akre 1979). Several different functions, such as sting 
lubrication, have been ascribed to the gland (Spradbery 1973, 
Maschwitz and Kloft 1971). The secretion is not considered toxic, 
although Barr-Nea et al. (1976) found some lethality to honey bees. 
Jeanne (1977) suggested that in D. arctica this gland may produce 
an allomone that has some pacifying effect upon the host queen 
and or workers. However, the mode of usurpation in D. arctica 
differs from that in V austriaca, suggesting a different function for 
the gland in the latter. D. arctica usually passively invades queen 
nests and coexists with the queen prior to the emergence of the host 
workers (Evans 1975, Greene et al. 1978, Jeanne 1977), while 
