Official name
Synonyms
Spilomena troglodytes [1]
Spilomena vagans
see more on: www.gbif.org
Etymology
troglodytes
Greek: cave-dweller
Contents
1. Distribution
2. Behaviour
3. Plant relations
4. Prey relations
5. Parasitic relations
6. Identification
1. DISTRIBUTION
Spilomena troglodytes is a rare wasp [2] occurring throughout the Netherlands [3,9] with an exception of the coastal provinces and the wadden islands [3]. It is the most common representative of the genus in the Netherlands [9].
2. BEHAVIOUR
2.1. ACTIVITY
The species is active from beginning of June to half September [3].
Males frequently can be found swarming around bushes and trees [3,12].
2.2. DEVELOPMENT
Nest
Females nest in existing cavities [3,4,5,9,12] in old wood [4,5,9,12], twigs [4] and abandoned beetle boreholes [9,12], with a preference [12] of those made by Anobium sp. (Anobiidae) [3,12] (Anobium rufipes [6], Microbregma emarginatum [6]). She will gnaw her own nest as well in the marrow of plant stems [3].
Existing boreholes are cleaned before use [3,12]. Gnawed corridors are about 4-12cm in length [5]. The corridors have a diameter of 1,0-1,4mm [5,8] and a length of 3,5-6 mm [8].
The brood cells are placed sequentially in a row within the nest cavity [3,5,12]. The brood cells are separated by a 1-2mm thick bulkhead made of wood dust [5] or a 0,2-7mm wedge-shaped pith plug [8]. Every cell contains 50-60 thrips [3,12]. Cells for females and males are equal in size [8].
The filled nest is closed with a wood pulp plug that is tamped using the abdomen [3,13]. The outermost layer is fortified by mixing the wood pulp with saliva that hardens as it dries [3] into a somewhat shiny disc [12].
Females find their nest using smell and as a result normally take a lot of time to find it after returning from the hunt, which is typical in the genus Spilomena [5,12]. They will scout around a large surface around the assumed nest position until they smelled it out using the antennae [5]
Development time
The development time of the relatively large (1,25 mm), weakly saussage-like bent [12] egg is unknown. The matt white cocoons are attached to the cell wall and occupy almost the entire cell length [8].
Gender development
The male and female brood cells are randomly placed in the nest cavity [5]. There are more female than male cells which results in a surplus of female over males in a ratio of 2:1 [5].
2.3. BEE HOTEL
The males as well as the females can be found on bee hotels. Females use them to nest.
From my own observation of a male arriving early in the evening I suspect the males to use empty boreholes as resting place, see here.
2.4. MATING
Most Crabronidae females produce one generation per year [8].
2.5. HUNTING
The prey is transported using the mandibles [4,12].
3. PLANT RELATIONS
3.1. WOOD
The following wood types are mentioned in literature as medium for the wasp to built her nests in:
| Adoxaceae (Muskuskruidfamilie) | Sambucus (Elder) [8] |
| Betulaceae (berkenfamilie) | Alnus (Elm) [3] Betula (Birch) [3] Carpinus (Hornbeam) [3] |
| Pinaceae (Dennenfamilie) | Picea Picea abies (Norway spruce) [6] |
| Rosaceae (Rozenfamilie) | Crataegus (Hawthorn) [3] Rubus (Bramble) [7,8] |
| Salicaceae (Wilgenfamilie) | Salix (Willow) [3] |
| Sapindaceae (Zeepboomfamilie) | Aesculus (Horse chestnut) – Horse chestnut (Aesculus hippocastanum) [6] |
Fence poles [3] or thatched roofs [12] may be used as well.
3.2. FOODPLANTS
Males feed with honeydew that is licked from leafs.
The following wood types are mentioned in literature as foodsources:
Apicaceae (Umbellifers) | Peucedanum [5] Foeniculum [5] Angelica [5] – Angelica archangelica [5] |
Garden species
In the garden Foeniculum vulgare is present but I have not observed the species on it.
4. PREY RELATIONS
The species uses mainly nymphs of thrips (Thysanoptera) for her brood [3,4,5,9,12]. Observations have been reported on the use of Psyllids (Psyllidae) nymphs [4] and the nymphs of Scale insects (Coccidae) and Aphids (Aphidoidea) [4].
The following species and group occurring in the Netherlands [1] are mentioned in literature:
| Aphidoidea (Aphids) [4,5] |
| Coccidae (Scale insects) [4,5] |
| Psyllidae (Psyllids) [4] |
| Thysanoptera (Thrips) [4] |
Garden species
At least Thrips and Aphids are present in the garden.
5. PARASITIC RELATIONS
The following species and group occurring in the Netherlands [1, 2(Oscinella nigerrima)] are mentioned in literature:
| Hymenoptera (Wasps) | Ichneumonidae (Ichneumon wasps) Neorhacodes – Neorhacodes enslini [3,8,10,12] Chalcidoidea (Chalcid wasps) Torymidae Torumus – Torymus armatus [3,8(as Diomorus armatus)] |
| Diptera (Flies) | Chloropidae (Frit flies) Oscinella – Oscinella nigerrima [4] |
6. IDENTIFICATION
Length males: 2 – 3 mm
Length females: 2,5 – 3 mm
Genus
The genus Spilomena can be identified using the following characters:
1. Forewing: with two submarginal cells [9,10,11]
2. Forewing: submarginal cell 2 not petiolate [9,10,11]
3. Forewing: pterostigma large and almost semicircular [9,10,11]
4. Forewing: radial cell longer than pterostigma [9,10,11]
5. Forewing: radial cell tip sharp [9,10,11]
6. Forewing: with one discoidal cell [9,10,11]
7. Abdomen: first abdominal segment not petiolate [9,10,11]
8. Abdomen: entirely black [9,10,11]
1. Antenna with 12 segments [9,10,11]
2. Abdomen with 6 segments [9,10,11]
HEAD
1. Clypeus evenly rounded [10]
2. Mandible usually light brown, seldom dark brown [10]
3. Ratio distance between hind ocelli (POL) : distance hind ocellus to eye edge (OOL) = 1,4 – 2,0 [10,11]
4. Back head less strongly developed [10]
THORAX
1. Frontal scutellem furrow narrow and without transverse carinae [10,11]
2. Apical edge mesonotum without longitudinal grooves [10]
3. Wing veins brown [10]
4. Dorsal field propodeum not limited by carina, at least at the base with net-like wrinkles between the main sculpture [10]
ABDOMEN
- Tergite 6 with double longitidunal carina [10]
specimen caught for identification on 10-vi-2021, length ±3mm
1. Antenna with 13 segments [9,10,11]
2. Abdomen with 7 segments [9,10,11]
3. Face and clypeus yellow, at least the front edge yellow (here face and clypeus) [9,10,11]
HEAD
1. Frontal edge clypeus not or lightly indented (here lightly indented) [10,11]
2. Mandible distally with small red-brown spot [10,11]
3. Clypeus entirely or almost entirely yellow [9,10]
4. Ratio distance between hind ocelli (POL) : distance hind ocellus to inner eye edge (OOL) = 1,4 – 2,0 (here ±1,4) [10,11]
5. Antennal members clearly restricted, bead-like [9,10,11]
6. Antennal flag dark, at most more or less red-brown on the inside [9]
THORAX
1. Frontal scutellum furrow narrow and without transverse carinae [9,10,11]
2. Dorsal field propodeum not limited by carina [9,10,11], at least at base with fine net-like wrinkles between the main sculpture [10]
ABDOMEN
no specific characters
References
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 BOHART, Richard M.; BOHART, Richard Mitchell; MENKE, Arnold S. Sphecid wasps of the world: a generic revision. Univ of California Press, 1976.
5 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
6 Vikberg, Veli. (2000). A re-evaluation of five European species of Spilomena with a key to European species and relevance to the fauna of North Europe, especially Finland (Hymenoptera : Pemphredonidae). Entomologica Fennica. 11. 35-55. 10.33338/ef.84044.
7 VAN LITH, J. P. De Nederlandse Spilomena-soorten (Hym. Sphecidae). Entomologische Berichten, 1955, 15.24: 525-527.
8 DANKS, Hugh V. Biology of some stem‐nesting aculeate Hymenoptera. Transactions of the Royal Entomological Society of London, 1971, 122.11: 323-395.
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 LOMHOLDT, O. 1975-1976; 1984 (2. Auflage). The Sphecidae (Hymenoptera) of Fennoscandia and Denmark. Fauna Entomologica Scandinavica, 4.1: 2.
