NESTING BIOLOGY OF OXYBELUS SERICEUS 
WITH A DISCUSSION OF NEST GUARDING BY MALE 
SPHECID WASPS (HYMENOPTERA) 
By Allan W. Hook 1 and Robert W. Matthews 
Department of Entomology 
University of Georgia 
Introduction 
Among sphecid wasps males are regularly associated with nesting 
females only in a few species. A review of territorial behavior in male 
sphecids (Alcock, 1975) has shown that such behavior is typically 
associated with obtaining copulations. Only rarely do males actively 
participate in nest maintenance or prey manipulation. Species of 
Oxybelus digger wasps show an unusual diversity of male behavioral 
adaptations. Several species display male nest guarding behavior, 
that is, a male defends a territory at sites of active nests and attempts 
to mate with the nesting female (Peckham et al., 1973; Peckham, 
1977). Females exhibit an unusual prey carriage (impalement on the 
sting), and provision nests in exposed substrate ‘with paralyzed 
Diptera. 
Oxybelus sericeus is distributed throughout the United States and 
into Mexico (Bohart and Schlinger, 1957) and has been studied 
briefly by Bohart and Marsh (1960), who reported nest guarding. 
Here we present results of a two year study of the biology and 
behavior of O. sericeus in Georgia and discuss the phenomenon of 
nest guarding in sphecid wasps. 
Methods 
Observations were conducted during 5 August to 15 September 
1977 and 12 May to 12 June, 7 to 10 September, 7 to 9 October 1978 
on St. Catherine’s Island, 30 miles south of Savannah, Georgia at five 
separate study sites. Three beach sites were used primarily in 1977. 
The sparse dune vegetation consisted primarily of sandspur ( Cenchrus 
sp.) navelwort ( Hydroctyl bonariensis Lam), and Croton punctatus 
Jacq. Air temperatures ranged between 32° and 40° C during May to 
'Present address: Department of Zoology and Entomology, Colorado State State 
University, FortCollins, Colorado 80523. 
Manuscript received by the editor June 6, 1980. 
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