Official name
Synonyms
Ectemnius cephalotes
Crabro cephalotes
Metacrabro quadricinctus
see more on: www.gbif.org
Etymology:
cephalotes
Latin: headed, with a head
INHOUD
1. Distribution
2. Behaviour
3. Plant relations
4. Prey relations
5. Parasitic relations
6. Identification
1. DISTRIBUTION
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].
2. BEHAVIOUR
2.1. ACTIVITY
the species is active from end May to half October [3].
2.2. DEVELOPMENT
Nest
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].
2.3. BEE HOTEL
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].
2.5. HUNTING
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].
3. FOODPLANTS
The adult wasps feed with nectar. The following plant groups and species are cited in literature as food plants:
| Asteraceae (Composite family) | – Carduus crispus (Welted thistle) [10] |
| Apicaceae (Umbellifers) [9,10,15] | – |
Garden species
The garden offers some Umbellifer species but I haven’t observed any Ectemnius species on it yet.
4. PREY RELATIES
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:
| Diptera (Flies) | Anthomyiidae Delia – Delia platura [14] Asilidae [3,7,8,9,10] Tolmerus – Tolmerus atricapillus [5] Calliphoridae [3,7,8,9,10] Calliphora – Calliphora vicina [5,14] – Calliphora vomitoria [5] Lucilia – Lucilia ampullacea [5] – Lucilia illustris [5] Onesia – Onesia floralis [5] Pollenia – Pollenia rudis [5] Protocalliphora – Protocalliphora azurea [5] Fanniidae Fannia – Fannia fuscula [14] Muscidae [3,7,8,9,10] Haematobia – Haematobia irritans [14] Helina – Helina impuncta [5] – Helina confinis [5] Hydrotaea – Hydrotaea irritans [5] Mesembrina – Mesembrina meridiana [5] Musca – Musca autumnalis [5] Muscina – Muscina prolapsa [5] – Muscina stabulans [5] Mydaea – Mydaea corni [14] – Mydaea othonevra [5] – Mydaea urbana [5] Neomyia – Neomiya cornicina [14] Phaonia – Phaonia angelicae [5] – Phaonia errans [5,14] – Phaonia rufiventris [5] – Phaonia subventa [5] – Phaonia trimaculata [5] – Phaonia tuguriorum [5] Polietes – Polietes lardarius [5,14] Rhagionidae [3,7,8,9,10] Rhagio – Rhagio scolopaceus [5] Sarcophagidae [3,7,8,9,10] Sarcophaga – Sarcophaga carnaria [5,14] Syrphidae [3,7,8,9,10] Episyrphus – Episyrphus balteatus Eupeodes – Eupeodes luniger [8,14] Scaeva – Scaeve pyrastri [14] Syrphus – Syrphus ribesii [5] – Syrphus vitripennis [5] Tabanidae [3,7,8,9,10] Tabanus – Tabanus bromius [5] |
Garden species
Look here to see which of these prey species have been observed in the garden.
5. PARASITIC RELATIONS
The following nest parasites of E. cephalotes present in the Netherlands are mentioned in the literature:
| Diptera (Flies) | Sarcophagidae (Flesh flies) Macronychia – Macronychia polyodon [17] |
Garden species
None of these parasites have yet been observed in the garden.
6. IDENTIFICATION
Length males: 9 – 14 mm
Length females: 12 – 17 mm
Genus
The genus Ectemnius can be identified using the following characters:
1. Front wing with one submarginal cell [9,10,11]
2. Ocelli usually form an obtuse isosceles triangle [9,10,11]
[JACOBS] specifies: often an acute angle [10].
3. Tergites abdomen smooth with fine punctation, only often slightly stronger on tergite 1 [4,5,11]
4. Side thorax, metapleuron (M) and often side propodeum (P), with strong transverse wrinkles [3,4,5,11]
5. Side thorax (mesopleuron) has a short, angular or curved transverse keel in front of middle coxa [4,5,11].
5. Head frontally wider than high [4,11]
specimen caught for photo identification on 11-vii-2021, length ±16mm
1. Antenna with 12 segments [9,10,11]
2. Abdomen with 6 segments [9,10,11]
HEAD
1. Length antennal member 3 usually less than 3x width [9,11]
2. Top antenal zone not limited by carina [9]
3. Clypeus hairs silver [9]
4. Clypeus with flat middle lobe, apical edge protruding and widely truncated [9,10]
5. Cheek (genae), distance eye-mandible, shorter than width antennal segment 2 [10,11]
THORAX
1. Thorax dorsally (mesonotum) with transverse stripes at front, and longitudinal stripes at back [10,11]
2. Thorax dorsally (mesonotum) and scutellum with more or less regular striped structure without punctation between the stripes [9]
3. Corners pronotum rounded [9,10,11]
4. Thorax dorsally (mesonotum) with long hairs [9]
5. Mesopleuron matt, wrinkled [9]
6. Front thorax side (mesopleuron) ventrally with transverse carina, connected to epicnemial carina [10,11]
mesosternum = underside mesopleuron [10]
7. Thighs forelegs ventrally widely marked yellow [10]
ABDOMEN
1. Tergite 1 with long hairs [9,10]
- Antennae with 12 segments [9,10,11]
2. Abdomen with 7 segments [9,10,11]
HEAD
1. Antennal segments without deformations [9,10,11]
2. Last antennal segment truncated [9,10,11]
3. Antennal segments not flattened [11]
THORAX
1. Mesonotum not punctated, but finely striped [9]
2. Side thorax, mesopleuron, matt with striped or wrinkled structure [9,11]
3. Trochanter front leg without tooth or keel [10,11]
4. Underside thigh (femur) front leg without tooth [10,11]
5. Metatarsus middle leg widened, short [9,10,11], with redbrown thorns [10]
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.
ABDOMEN
1. Tergite 7 without pygidium [9]
2. Tergite 7 with longitudinal furrow [9,11]
Literature
1 Nederlands Soortenregister2 Waarneming.nl
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. https://doi.org/10.1002/mmnz.20020780208
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, R.M. & A.S. Menke, 1976. Sphecid wasps of the world: a generic revision. - University of California Press, 695 p.
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.
