Table Of ContentPROC. ENTOMOL. SOC. WASH.
109(1), 2007, pp. 182-186
NESTING HABITS OF ECTEMNIUS SCABER (LEPELETIER AND BRULLE)
(HYMENOPTERA: CRABRONIDAE)
E. E. Grissell
P.O. Box 739, 38 Terry Lane, Sonoita, AZ 85637-0739, U.S.A. (e-mail:
[email protected])
—
Abstract. Ectemnius scaber (Lepeletier and Brulle) was found nesting in a dried
flower stalk of parsley {Petroselinum crispum Nyman). A single entrance hole was
made 30 cm above ground level. Five cells, each provisioned with Toxomeriis
marginatus Say (Diptera: Syrphidae), were constructed above the entrance point.
This is the first report of the genus as a host for Ectemnius. The biologies of seven
species of Nearctic Ectemnius and three Holarctic species are reviewed.
Key Words: Hymenoptera, Crabronidae, Syrphidae, Ectemnius scaber, Toxomerus
marginatus
The genus Ectemnius Dahlbom com- Spring, Montgomery County, Maryland.
prises 184 species worldwide (Pulawski While cutting the vertical, spent flower
2005) of which 27 are Nearctic (Bohart stalks of parsley (Petroselinum crispum
and Kimsey 1979). Species are known to Nyman) I noticed a quantity of white,
provision their nests with adult flies and powdery "sawdust" on the leaves of one
nest in decaying and rotten wood, pithy plant. I found an entrance hole in one
plant stems, or in the ground (Tsuneki stalk. Icut the stematthebase and tookit
1960, Court 1976, Takumi 1999, Pu- to my lab the following day. After slicing
lawski 2005). the stem vertically I took a series ofdigital
In this paper I present new nest in- photos using a Nikon Coolpix 90 camera.
formation and prey records for Ectemnius The stem halves were taped together and
scaber (Lepeletier and Brulle) for which placed in a cardboard rearing container
no previous documented records have with the lid replaced by a black funnel to
been published. Although Krombein which was attached a clear plastic vial.
(1979) listed a record as "nests in pine" The container was placed in the refriger-
this record remains unsubstantiated and ator at 40 F (4.5°C) until mid-March
is almost certainly incorrect based on 2005 at which point it was removed and
direct observations presented below. In placed next to an interior window. Two
addition to these observations I present adult female wasps emerged into the
a review ofthe biology ofNearctic species rearing vial on 18 April.
based on the comprehensive overview of Identification ofreared adult wasps was
Sphecidae given by Pulawski (2005). madeusing Bohart and Kimsey(1979) and
comparison with specimens in the collec-
Methods
tion of the National Museum of Natural
Nest material was collected in my History. Voucher specimens of the wasps
garden on 29 August 2004 in Silver have been placed in that museum.
VOLUME NUMBER
109. 1 183
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Results Adult emergence. Adult emergence
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Nest structure (Figs. 1-3). The nest appears to be from the top of the stem
entrance, 3 mm in diameter, was located downward and out the entrance hole as
about midway up the 60 cm drying there were no other exterior exits and the
flower stalk, and about 4.5 cm below pith plug above the topmost cell was not
breached. The plug beneath had been
a branching point (Fig. 2; stem removed,
burrowed through.
stub visible). The inner wall of the stem —
was lined with a thin layer of irregular Host. Prey were identified as Tox-
omerus inarginatus Say (Diptera: Syrphi-
pith abutting the outer wall. Five cells
dae).
were found in linear fashion, all built
above the nest entrance. The section of Discussion
mm
stem with cells was about 6-7 in
The above description disagrees with
diameter with a central hollow core
mm that of Krombein (1964) for Ectemnius
about 4 in diameter. The topmost
cell was about 16 cm above the entrance paucunaculatus in that the cell construc-
c(Foingssi.st1e,d3)o.fFtrhoremetporpetpoupbaoettionmctohceoocnelsl,s ttoiobneatnhdeleaxyacotutre(vheirssefigosf.E7.a,sc7abb)era.pIpeaamr
confident about the orientation of the
one larva spinning a cocoon, and one stem in my Figs. 1-3, and those of
feeding larva (Fig. 3). The two larvae Krombein appear to be correct as well,
nearest the entrance indicate that the
so perhaps the differences are distinctive
wasp worked from the top down. The
of the species.
wveanstearboouftt4h.e5lcomwesftrocmellth(emoesnttrarneccee.nt)I pauKcruonmacbueliantus(1t9h6e4)wansopteedggtwhaats lfaoird oEn.
could not determine if the nest had been the first provisioned fly, whereas Hook
completed, but the space from the most
(1982) found that for E. centralis the egg
recent cell to the entrance was empty was laid on the last provisioned fly but
indicating that more cells could have that the prey were then rearranged with
been constructed in the stem. that fly placed farthest into the cell. With
Each completed cell (Fig. 3) contained E. scaber the fly remains are compressed
(top to bottom) a pith plug (white), against the top of the cell which might
a compressed mass of intertwined fly indicate that it feeds upon the flies from
pieces (black), a cocoon (brown) or larva below pushing their remains upward as it
(white), and an empty gap before the next feeds and creating a gap between itself
pith plug. No meconia were seen. The and the bottom pith plug. This seems
measurements for each cell are: pith plug rather odd but fits the cell construction
= 10-12 mm; fly mass = 2-3 mm; co- pattern.
coon 8 10 mm or larva 8-9 mm; gap 5- Among Nearctic species, only two
6 mm. Thetotalcelllengthvariedfrom20 have been reported using syrphids as
to 30 mm. Two cocoons were suspended prey. Ectemnius spiniferus Fox, which
from the top of the cell but the topmost normally provisions with acrocerid flies,
cocoon was disturbed when the stem was was found to have a single syrphid prey
cut and thus is at the bottom ofthe cell in in one cell (Bechtel and Schlinger 1957),
Fig. 3. Based on the orientation of these and E. maculosus (Gmelin) had prey
bands it appears that the fly prey are listed as "syrphids" with no additional
placed in the cell after the pith plug is data (Krombein 1963b). Three Palearctic
made. Placement ofan egg with respect to species are known to use syrphids as
the prey is unknown for Ectemniusscaber prey: E. cavifrons (Thomson), E. confinis
because no eggs were found. (Walker), and E. sexcinctus (Fabricius),
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON
184
attached
pupal
case
Figs. 1-3. ParsleystemnestofEctemniusscaber. 1, Stemaboveentrancehole,areaofcellconstruction
indicated by dashed line. 2, Entrance hole. 3, Cross section ofstem, rule in mm.
VOLUME NUMBER
109, 1 185
as is the Holarctic species E. lapidarius Lonchaeidae, Sciomyzidae, Sphaerocer-
(Panzer) (summarized by Pulawski idae, and Muscidae. Evans (1964: fig.
2005). 113) described and illustrated the larva
Because there is Httle available litera- of this species based on material from
ture pertaining to the biology ofNearctic Krombein's study.
Ectemnius, I present a summary of what Ectemnius stirpicola (Packard): Evans
is known, drawn from the world catalog (1957: figs. 85 89) described and illus-
of Pulawski (2005). trated the larva. Later he added a few
Ectemnius atriceps (Cresson): Evans additional notes to his description
(1957: figs. 91-94) described and illus- (Evans 1959). Krombein (1963b) listed
trated the larvacollected in a Sambucus this species (as "'stirpicda,'" a lapsus)
stem. Krombein (1963b, as Ectemnius nesting in twigs and preying on small
brunneipes (Packard)) reported this acalyptrate muscoid flies.
species nesting in logs. Ectemnius spiniferus Fox: Bechtel and
Schlinger (1957) reported this species
Ectemnius centralis Cameron: Hook
nesting in dead or dying twigs of
(1982) reported this species nesting in
elderberry {Sambucus coerulea Rafin-
a broken, dead limb of live oak esque). Each wasp created a single,
{Quercus sp.), which he characterized linear burrow with up to 6 cells. Prey
as decaying. Each wasp created side
consisted mostly of Acroceridae {Og-
burrows branching off a central nest
codes eugonatus Loewe) but there were
burrow. These side burrows contained
also a fewAnthomyiidae {Hylemya sp.),
1 or 2 cells arranged linearly. Prey and a single Syrphidae {Sphaerophoria
consisted of flies in the families Stra- sp.). A large number of Phoridae
tiomyiidae, Bombliidae, Sarcophagi-
{Megaselia sp.) were present, but these
dae, Muscidae, and Tachinidae.
appeared to be scavengers and not prey.
Ectemnius exccivatus (Fox): Krombein
(1963b) reported this species nesting The following species are Holarctic
in rotten logs. taxa for which there is minimal data in
Ectemnius maculosus (Gmelin): Krom- the Nearctic:
bein (1963b, as Ectemniussingularis (F.
Ectemnius continuus (Fabricius): Krom-
Smith)) reported this species provi-
bein (1963a) reported this species
sioning with unidentified Syrphidae.
nesting in a rotten pear limb. There
Ectemnius paucimciculatus (Packard):
were seven or eight cells which pre-
Krombein (1964) wrote and illustrated
sumably were arranged in a linear
anextensivepaperonthis species, which
burrow. Prey consisted of Diptera in
is the best known ofall Nearctic taxa. It
the families Calliphoridae, Tachinidae,
makes linear cells in stems of hibiscus
Sarcophagidae, and Muscidae, each
{Hibiscus militaris Cavanilles). The
being represented by few individuals.
number of cells varied from 1 to 13 The larva was described and illustrated
below the entrance and from 1 to 8 by Evans (1964: fig. 114) based on
above the entrance. Ninety-nine percent
material from Krombein. The species
of the prey consisted equally of Agro-
also was reported nesting in logs by
myzidae {Melanagromyza diantherae
Krombein (1963b).
(Malloch)) and several species ofEphy-
dridae (Notiphi/a carinata Loew; Hy- Ectemnius dives (Lepeletier and Brulle):
drellia spp.). Additional families each Krombein (1963b) listed this species
represented by a few specimensincluded nesting in logs, timber, and stems. It
Dolicopodidae, Ottitidae, Lauxaniidae, provisioned with muscoid flies.
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON
Ectemnius lapidarius (Panzer): Krombein . 1959. Studieson thelarvae ofdiggerwasps
(1963b) reported this species nesting in (Hymenoptera, Sphecidae) part IV: Conclu-
rotten wood and provisioning with sion. Transactions of the American Entomo-
logical Society 85: 137-191.
unidentified Syrphidae and Antho- 1964. Further studies on the larvae of
.
myiidae. digger wasps (Hymenoptera: Sphecidae).
Transactions of the American Entomological
Society 90: 235-299.
Acknowledgments Hook, A. 1982. Notes on nesting behavior of
Ectemnius centralis (Cameron) (Hymenoptera:
I thank Chris Thompson, Systematic Sphecidae). Entomological News 93: 75-76.
Entomology Laboratory, for the identi- Krombein, K. V. 1963a. Miscellaneous prey re-
fication of host syrphids. I thank Woj- cords of solitary wasps. V. (Hymenoptera:
ciech Pulawski, California Academy of Aculeata). Bulletin of the Brooklyn Entomo-
logical Society 58: 118-120.
Sciences, San Francisco, for reading the 1963b. Natural history of Plummers
manuscript and correcting many factual Isla.nd, Maryland. XVII. Annotated list of
and nomenclatural errors. The input of thewasps(Hymenoptera: Bethyloidea, Scolioi-
an unidentified reviewer was also helpful, dea, Vespoidea, Pompiloidea, Sphecoidea).
Proceedings of the Biological Society of
and I accepted most, if not all, of his or Washington 76: 255-280.
her voluminous suggestions with appre- 1964. Natural history ofPlummers Island,
.
ciation. Maryland. XVIII. The hibiscus wasp, an
abundant rarity, and its associates (Hymenop-
tera: Sphecidae). Proceedings ofthe Biological
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