Ectemnius cephalotes♀︎♂︎

Last update: 28 May 2023


SPECIES: Ectemnius cephalotes




Official name


Ectemnius cephalotes

Crabro cephalotes
Metacrabro quadricinctus

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Latin: headed, with a head

Ectemnius cephalotes ♂︎


1. Distribution
2. Behaviour
3. Plant relations
4. Prey relations
5. Parasitic relations
6. Identification


The digger wasp Ectemnius cephalotes is an uncommon wasp that can be found across the Netherlands, with an exception to the northern provinces  [2,3,4].



the species is active from end May to half October [3].



Widely branched nests are gnawed in different kinds of old rotten wood [3,5] like old oak [3,4], birch [8] and poplar stems [3,15], but also conifer [4]. Sometimes in newer wood as well [4,7,13,14].

The nest starts with a straight corridor that branches off into numerous short side corridors [4,5,8]. At the end of the corridor a broodcell is constructed, the ones intended for males are smaller than those for the females [4,8].

Sometimes larger groups of females will nest together in nestaggregations [3,4,5,8]. They use the same entrance and main corridor from which each will gnaw their own branches [5,8].

Larvae are fed with flies [3,4,5,8].  After the broodcells are stocked the corridors are filled with sawdust [5]. The eggs are placed on the sides of the prey last added [8].

Development time

After about three days the eggs will hatch [4,8], and the following development of the larva will take two to three weeks [8]. Then a cocoon is spun in which the larva hibernates [8]. The pupal development will take two to three weeks [8], followed by the emergence of the adult which will live for two to three months [8].

One generation is produced per year, but in long summers two generations are possible [5].


The males will use the bee hotels as sleeping place [6]. Occasionally a fresh female without a nest may do so as well [6].

On numerous occasions I have observed how a male that is searches for a suitable spot will hang around the hotels for quite some time, land below an opening, throw a quick glance to inspect the potential spot and take off again. He will land with the antennae directed towards the entrance to sniff it out and crawl head first partially, or entirely inside.
It can take a large part of an hour before the right spot has been found, in which case he will crawl out backwards from the tunnel, turn in front of the entrance and crawl in backwards again so it’s head is pointed towards the entrance when inside.

2.4. Mating

Crabronidae females probably mate only once [15].


Ectemnius females may actively hunt prey by slowly flying through the herb layer [8]. When she has spotted a prey she will approach it slowly hovering, and once a positive identification is made she explosively accelerates forward catching the prey with spread mandibles and front legs [8]. This is learned behaviour that she will practise a lot before mastering [8].

Probably Ectemnius can focus it’s vision on a distance of 15 – 20 cm [8].


The adult wasps feed with nectar. The following plant groups and species are cited in literature as food plants:

(Composite family)
Carduus crispus (Welted thistle) [10]
(Umbellifers) [9,10,15]

Garden species

The garden offers some Umbellifer species but I haven’t observed any Ectemnius species on it yet.


The species ise flies as food for her brood [3,7,8,9,10].
The following prey groups and species present in the Netherlands [1] are cited in literature:

Delia platura [14]

Asilidae [3,7,8,9,10]
Tolmerus atricapillus [5]

Calliphoridae [3,7,8,9,10]
Calliphora vicina [5,14]
Calliphora vomitoria [5]

Lucilia ampullacea [5]
Lucilia illustris [5]

Onesia floralis [5]

Pollenia rudis [5]

Protocalliphora azurea [5]

Fannia fuscula [14]

Muscidae [3,7,8,9,10]
Haematobia irritans [14]

Helina impuncta [5]
Helina confinis [5]

Hydrotaea irritans [5]

Mesembrina meridiana [5]

Musca autumnalis [5]

Muscina prolapsa [5]
Muscina stabulans [5]

Mydaea corni [14]
Mydaea othonevra [5]
Mydaea urbana [5]

Neomiya cornicina [14]

Phaonia angelicae [5]
Phaonia errans [5,14]
Phaonia rufiventris [5]
Phaonia subventa [5]
Phaonia trimaculata [5]
Phaonia tuguriorum [5]

Polietes lardarius [5,14]

Rhagionidae [3,7,8,9,10]
Rhagio scolopaceus [5]

Sarcophagidae [3,7,8,9,10]
Sarcophaga carnaria [5,14]

Syrphidae [3,7,8,9,10]
Episyrphus balteatus

Eupeodes luniger [8,14]

Scaeve pyrastri [14]

Syrphus ribesii [5]
Syrphus vitripennis [5]

Tabanidae [3,7,8,9,10]
Tabanus bromius [5]

Garden species

Look here to see which of these prey species have been observed in the garden.


The following nest parasites of E. cephalotes present in the Netherlands are mentioned in the literature:

Sarcophagidae (Flesh flies)
Macronychia polyodon [17]

Garden species

None of these parasites have yet been observed in the garden.


Length males: 9 – 14 mm
Length females: 12 – 17 mm


The genus Ectemnius can be identified using the following characters:

1. Front wing with one submarginal cell [9,10,11]

Ectemnius cephalotes ♂︎, Ectemnius: Voorvleugel met 1 submarginaal cel

2. Ocelli usually form an obtuse isosceles triangle [9,10,11]

[JACOBS] specifies: often an acute angle [10].

Ectemnius cephalotes ♂︎, Ectemnius: ocelli form an obtuse triangle

3. Tergites abdomen smooth with fine punctation, only often slightly stronger on tergite 1 [4,5,11]

Ectemnius cephalotes ♂︎, Ectemnius: tergites smooth with fine puctation

4. Side thorax, metapleuron (M) and often side propodeum (P), with strong transverse wrinkles [3,4,5,11]

Ectemnius cephalotes ♂︎, Ectemnius: side thorax strongly wrinkled

5. Side thorax (mesopleuron) has a short, angular or curved transverse keel in front of middle coxa [4,5,11].

Ectemnius cavifrons ♂︎, Ectemnius: side thorax (mesopleuron) in front middle coxa with short transverse keel

5. Head frontally wider than high [4,11]

Ectemnius cephalotes ♂︎

specimen caught for photo identification on 11-vii-2021, length ±16mm

Ectemnius cephalotes ♀︎
Ectemnius cephalotes ♀︎
Ectemnius cephalotes ♀︎
Ectemnius cephalotes ♀︎
Ectemnius cephalotes ♀︎
Ectemnius cephalotes ♀︎

1. Antenna with 12 segments [9,10,11]

Ectemnius cephalotes ♀︎, antenna with 12 segments

2. Abdomen with 6 segments [9,10,11]

Ectemnius cephalotes ♀︎, abdomen with 6 segments


1. Length antennal member 3 usually less than 3x width [9,11]

Ectemnius cephalotes ♀︎, length (l) antennal segment 3 usually less than 3x width (w)

2. Top antenal zone not limited by carina [9]

Ectemnius cephalotes ♀︎, antenal zone top not limited by ridge

3. Clypeus hairs silver [9]

Ectemnius cephalotes ♀︎

4. Clypeus with flat middle lobe, apical edge protruding and widely truncated [9,10]

Ectemnius cephalotes ♀︎, clypeus with flat lobe, frontal edge prominent and widely truncated

5. Cheek (genae), distance eye-mandible, shorter than width antennal segment 2 [10,11]

Ectemnius cephalotes ♀︎, cheeks (genae) shorter than antennal segment 2


1. Thorax dorsally (mesonotum) with transverse stripes at front, and longitudinal stripes at back [10,11]

Ectemnius cephalotes ♀︎, front mesonotum with transverse tripes, back with longitudinal stripes

2. Thorax dorsally (mesonotum) and scutellum with more or less regular striped structure without punctation between the stripes [9]

mesonotum (M) and scutellum (S) with clear, more or less regular, striped structure without punctures in between the stripes

3. Corners pronotum rounded [9,10,11]

Ectemnius cephalotes ♀︎, pronotum corners rounded

4. Thorax dorsally (mesonotum) with long hairs [9]

Ectemnius cephalotes ♀︎, mesonotum with long hairs

5. Mesopleuron matt, wrinkled [9]

Ectemnius cephalotes ♀︎, mesopleuron matt and wrinkled

6. Front thorax side (mesopleuron) ventrally with transverse carina, connected to epicnemial carina [10,11]

mesosternum = underside mesopleuron [10]

Ectemnius cephalotes ♀︎, ventral front mesopleuron with transverse carina (c) connected to epicnemial carina (e)

7. Thighs forelegs ventrally widely marked yellow [10]

Ectemnius cephalotes ♀︎, underside thigh foreleg broadly yellow marked


1. Tergite 1 with long hairs [9,10]

Ectemnius cephalotes ♀︎, Tergite 1 with long hairs

Ectemnius cephalotes ♂︎
Ectemnius cephalotes ♂︎
Ectemnius cephalotes ♂︎
Ectemnius cephalotes ♂︎
Ectemnius cephalotes ♂︎, propodeum

  1. Antennae with 12 segments [9,10,11]
Ectemnius cephalotes ♂︎, antenna male with 12 segmenten

2. Abdomen with 7 segments [9,10,11]

Ectemnius cephalotes ♂︎, abdomen with 7 segments


1. Antennal segments without deformations [9,10,11]

Ectemnius cephalotes ♂︎, antennae without deformations
Ectemnius cephalotes ♂︎, antennae without deformations

2. Last antennal segment truncated [9,10,11]

Ectemnius cephalotes ♂︎, last antennal segment trunctated

3. Antennal segments not flattened [11]

Ectemnius cephalotes ♂︎, antennae segments not flattened


1. Mesonotum not punctated, but finely striped [9]

Ectemnius cephalotes ♂︎, mesonotum not punctated, but finely striped

2. Side thorax, mesopleuron, matt with striped or wrinkled structure [9,11]

Ectemnius cephalotes ♂︎, mesopleuron matt with striped or wrinkled structure

3. Trochanter front leg without tooth or keel [10,11]

Ectemnius cephalotes ♂︎, trochanter front leg without tooth or keel

4. Underside thigh (femur) front leg without tooth [10,11]

Ectemnius cephalotes ♂︎, thigh (femora) front leg underside without tooth

5. Metatarsus middle leg widened, short [9,10,11], with redbrown thorns [10]

Ectemnius cephalotes ♂︎, metatarsus middle leg widened, short and with redbrown thorns

5. Mesothorax ventral front with transverse keel.

The male E. cephalotes is the only Dutch Ectemnius for which [DOLLFUSS] [11] does not mention this character.

Ectemnius cephalotes ♂︎, underside mesothorax frontally with transverse keel
Ectemnius cephalotes ♂︎, underside mesothorax frontally with transverse keel
Ectemnius cephalotes ♂︎, underside mesothorax frontally with transverse keel


1. Tergite 7 without pygidium [9]
2. Tergite 7 with longitudinal furrow [9,11]

Ectemnius cephalotes ♂︎, tergite 7 without pygidium, with longitudinal furrow


1 Nederlands Soortenregister


3 Peeters, T.M.J., C. van Achterberg, W.R.B. Heitmans, W.F. Klein, V. Lefeber, A.J. van Loon, A.A. Mabelis, H. Nieuwen-huijsen, M. Reemer, J. de Rond, J. Smit, H.H.W. Velthuis, 2004. De wespen en mieren van Nederland (Hymenoptera: Aculeata). – Nederlandse Fauna 6. Nationaal Natuurhistorisch Museum Naturalis, Leiden, knnv Uitgeverij, Utrecht & European Invertebrate Survey – Nederland, Leiden.

4 Blösch, M. (2000). Die Grabwespen Deutschlands – Lebens‐weise, Verhalten, Verbreitung. 71. Teil. In Dahl, F.: Die Tierwelt Deutschlands. Begr.: 1925. – Keltern (Goecke & Evers). – 480 S. 341 Farbfotos. ISBN 3‐931374‐26‐2 (hardcover). DM 98,–. Zool. Reihe, 78: 353-353.

5 Hamm, A. & Richards, O.. (2009). The biology of the British Crabronidae. Transactions of the Royal Entomological Society of London. 74. 297 - 331. 10.1111/j.1365-2311.1926.tb02241.x.

6 Breugel, P. van 2014. Gasten van bijenhotels. – EIS Kenniscentrum Insecten en andere ongewervelden & Naturalis Biodiversity Center, Leiden.

7 Ruchin, Alexander & Antropov, Alexander. (2019). Wasp fauna (Hymenoptera: Bethylidae, Chrysididae, Dryinidae, Tiphiidae, Mutillidae, Scoliidae, Pompilidae, Vespidae, Sphecidae, Crabronidae & Trigonalyidae) of Mordovia State Nature Reserve and its surroundings in Russia. Journal of Threatened Taxa. 11. 13195-13250. 10.11609/jott.4216.11.2.13195-13250.

8 LOMHOLDT, O. 1975-1976; 1984 (2. Auflage). The Sphecidae (Hymenoptera) of Fennoscandia and Denmark. Fauna Entomologica Scandinavica, 4.1: 2.

9 KLEIN, Wim. De graafwespen van de Benelux. Jeugdbondsuitgeverij, Utrecht, 1996, 1-130. + KLEIN, Wim. De graafwespen van de Benelux: supplement. Jeugdbondsuitgeverij, 1999.

10 JACOBS, H. J (2007): Die Grabwespen Deutschlands Ampulicidae. Sphecidae, Crabronidae–Bestimmungsschlüssel in Blank, SM & Taeger, A (Hrsg): Die Tierwelt Deutschlands und der angrenzenden Meeresteile nach ihren Merkmalen und nach ihrer Lebensweise, Hymenoptera III–Keltern, Goecke & Evers, 79: 1-207.

11 Hermann Dollfuss, "Bestimmungsschlüssel der Grabwespen Nord- und Zentraleuropas (Hymenoptera, Sphecidae) mit speziellen Angaben zur Grabwespenfauna Österreichs", Publikation der Botanischen Arbeitsgemeinschaft am O.Ö.Landesmuseum Linz, LINZ, 20. Dezember 1991

12 BOHART, Richard M.; BOHART, Richard Mitchell; MENKE, Arnold S. Sphecid wasps of the world: a generic revision. Univ of California Press, 1976.

13 BOREHAM HJ Some details of the life and hàbits of the digger wasp Metacrabro quadricinctus Fab le Ectemnius 4 cinctus Suffolk Nat Soc Trans 11 1 46 50 1958 410 9 Su2

14 WOYDAK, Horst. Hymenoptera Aculeata Westfalica Familia: Sphecidae (Grabwespen), 1996, 3-135.

15 POVOLNY, D. The flesh-flies of Central Europe (Insecta, Diptera, Sarcophagidae). Spixiana supplement, 1997, 24: 1-260.