A DESCRIPTION OF THE 
ECTAL MANDIBULAR GLAND IN THE PAPER WASP 
POLISTES FUSCATUS (HYMENOPTERA: VESPIDAE)* 
By H. A. Downing and R. L. Jeanne 
Department of Entomology 
University of Wisconsin 
Madison, Wisconsin 53706 
While the ectal mandibular gland is a source of queen substance 
in both honey bees and bumble bees (Butler and Simpson, 1958; van 
Honk et al., 1980), little is known about this gland in the vespids. 
In Vespula and Polistes spp. the mandibular gland consists of 50 to 
70 ducted gland cells opening into a reservoir which in turn is said to 
empty into the oral cavity at the base of the mandible (Hermann et 
al., 1971; Spradbery, 1973; Landolt and Akre, 1979). Nedel (1960), 
however, found that the mandibular gland of V. germanica (F.) 
opens anterior to the anterior condyle and thus to the front of the 
face. He describes a small brush of mechanoreceptors on the 
mandible. 
Because the mandibular gland is so much smaller in wasps than in 
bees, Spradbery (1973) suggested that it probably has no social 
function in wasps. However, the fact that this gland is the largest of 
the cephalic exocrine glands in wasps and the discrepancies in the 
literature concerning the locus of the gland opening caution against 
such a conclusion. The purpose of the present study is to investigate 
the morphology of the ectal mandibular gland in Polistes fuscatus 
with reference to possible gland function. 
Methods 
Micrographs of the exterior opening of the ectal mandibular 
gland were taken using the JELCO JSM-U3 scanning electron mi- 
croscope. Quarter sections of female wasp heads containing the ectal 
mandibular gland were fixed in Kahle’s solution and embedded in 
Spurr Low-Viscosity embedding media (Polysciences) following the 
methods of Spurr (1969). Sections 2/u thick were cut with a glass 
* Manuscript received by the editor September 23, 1982. 
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