BRN 9-2 (uncompressed) - Flipbook - Page 95
Tribe Bembicini
Sand Wasp
Not all of the wasps swarming these
Seepwillows were large. There were
also small yellow and black (Òyellow
jacket typeÓ wasps) crawling around.
These proved to be in the Tribe
Bembicini, the Sand Wasps. There are
roughly 200 species, in 27 genera,
within this tribe, in North America
north of Mexico. All of the species in
this tribe prey on other insects (ÒA
review of prey choice in bembicine
sand waspsÓ, Neotropical Entomology
31-1, March 2002). Wasps in this
tribe immobilize prey and store them
in their nests and lay eggs on the
prey. Once the larvae hatch they eat
the prey the adult left for them. Prey
species varies depending on geographic range, prey abundance, and
the prey species which are available
for predation. Prey are typically, but
not exclusively, ßy species. The article
cited above notes ÒThat sand wasps
learn sources of prey and return
repeatedly to these sources is well
known. . . . Females providing prey for
larvae in a nest, or bearing a mature
oocyte and having just Þnished
digging a nest, are under pressure to
Þnd food quickly. Under situations of
scarcity of the usual prey, as a result
of climatic factors or competition from
other species, females may undergo a
lowering of the threshold of response
or - to put it another way - a
broadening of sensory focusing on
images of a certain size - such that
alternate prey are seized and
utilized.Ó
A signiÞcant reference for this tribe is
The Sand Wasps - Natural History and
Behavior by Howard E. Evans and
Kevin M. OÕNeill, 2007, Harvard
University Press.
Stictiella pulchella
The common name for species in the
genus Stictiella (J. Parker, 1917) is
Butterßy-wolf Wasps. (BugGuide
cites Parker as the original describer
of this genus, Wikipedia cites Cresson,
1865 as the original describer of the
species.) In North America, north of
Mexico, there are 12 species in this
genus.
The original species description was
based on a specimen from Colorado.
In ÒObservations on the Behavior of
Digger Wasps of the Genus StictiellaÓ,
Gillaspy, Evans, and Lin note that this
species appears to prey exclusively on
Lepidoptera (Annals of the Entomological Society of America, Volume 55,
Issue 5, pp. 559-566, 1 September
1962).
94
ÒSpecies of Stictiella attempt to level
the mound of soil that accumulates in
front of an entrance from burrow
excavation. The species temporarily
close the entrance with soil following
burrow excavation and then make an
orientation ßight before going in
search of prey. Species of Stictiella
hunt and stock underground cells
with adult Lepidoptera (moths,
skippers, butterßies). Stictiella
nests are one-, two- or many-celled
depending on the species. The
number of prey per cell is often
inversely related to prey size. Most
Stictiella species practice delayed
mass provisioning; i.e., they lay an
egg on the Þrst prey placed in the cell
before other prey are put inside.Ó
(ÒNesting Behavior, Ecology, Seasonal
and Geographic Distribution of the
Sand Wasp, Stictiella emarginata
[Hymenoptera: Sphecidae])Ó
Kurczewski and Boyle, The Canadian
Field-Naturalist, Volume 119,
pp. 6-15.)
