3. Plant relations
4. Prey relations
5. Parasitic relations
S. bifasciatus  is a common species that can be found throughout the Netherlands, with exception of the provinces Zeeland and Groningen where the species is rare [2,3].
The species is active from May until half September [2,3].
S. bifasciatus nests usually in hollow stemms, but may be found in walls (also of buildings) and dead wood . She uses bee hotels as well and can be found in galls of the grass fly genus Lipara (CHLOROPIDAE) .
The female normally fills a nest cel with one prey, but sometimes two or more prey specimen are used when there is an abundance .
The female applies an adaptive strategy when building nests, so that the length of the cell is changed based on the diameter of the bore hole . The resulting cel has effect on the sex of the wasp that develops in that longer cells will produce more and heavier females . There is no effect on males .
Also the larger the number of cells in a nesting cavity the less females will be produced. Older females will construct less cells and provide less provisions, and from those cell less females will develop .
The wasp uses artificial nest help and has a preference for :
– nest blocks located at 1 to 2 meters in height
– nest blocks with an orientation north or west (hypotheses), she uses nest blocks with southern or eastern orientation as well
– bore holes 3-4 mm in diameter
3. PLANT RELATIONS
3.1. FOOD PLANTS
Adult S. bifasciatus wasps feed with necter and/or pollen. In literature the following plant species and groups are mentioned :
|Apicaceae||Pastinaca sativa |
3.2. PREY PLANTS
Research has shown that prey is found in different tree species and that S. bifasciatus is flexible in finding appropriate prey sources. The following trees have been identified:
|Populus tremula |
|Salix sp. [4,9]|
|Alnus incana |
As far as I know these trees are not in the vicinity of the garden, which may explain that I only found the species once so far.
4. PREY RELATIONS
The species is narrow oligophagous on beetlelarvae from the family of leaf beetles (CHRYSOMELIDAE) . Literatuur mentions the following species that occur in the Netherlands:
|CHRYSOMELINAE||– Plagiosterna aenea (Linaeidea aenea) |
– Phratora laticollis 
– Phratora vitellinae 
– Phratora vulgatissima [4,9]
– Plagiodera versicolora 
5. PARASITIC RELATIONS
The following nest parasites on S. bifasciates are mentioned in literature:
|– Chrysis ignita [3,8]|
– Chrysis angustula 
– Chrysis viridula (gezien bij nesten) 
|– Melittobia acasta |
The following of these parasites have been observed in the garden:
|– Chrysis ignita|
Length males: 7 – 11 mm
Length females: 7 – 11 mm
Symmorphus can be recognized by the longitudinal groove on tergite 1 . It also has a medial keel on tergite 1, a characteristic it shares with the genus Ancistrocerus.
2. Thorax with short hairs, hairs on top (mesonotum) dark, hairs sides (mesopleura) light 
3. Pronotum with continuous keel from reaching the tip 
4. Antennal shaft black 
7. Tergites 1, 2 and 4 with yellow band, tergite 3 sometimes with yellow spot 
The variant S. bifasciatus eumenoides has two yellow kidney-shaped spots on tergite 2 .
8. Top part mesopleuron, above transverse groove, with large and deep pits, the space between the pits is smaller than pit diameter. 
9. Vertical part tergite 1 shorter than the horizonal part
1. Antenna with 12 segments 
1. Antenna with 13 segments 
2. Antennal segment 13 as long as wide 
References1 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 Budrienė, Anna. (2003). Prey of Symmorphus Wasps (Hymenoptera: Eumeninae) in Lithuania. Acta Zoologica Lituanica. 13. 306-310. 10.1080/13921657.2003.10512686.
5 BUDRIENE, Anna. Reproductive ecology and behaviour of predatory wasps (Hymenoptera: Eumeninae). Doctor al thesis. Vilnius, 2004.
6 AMOLIN, A. V.; OGOL, I. N. Ïèùåâûå ñâÿçè ñêëàä÷àòîêðûëûõ îñ (Hymenoptera: Vespidae) ñ öâåòêîâûìè ðàñòåíèÿìè (Magnoliophyta) â Äîíáàññå Trophic relations of wasps (Hymenoptera: Vespidae) with flowering plants (Magnoliophyta) in Donbass.
7 SCHMID-EGGER, C. H. Bestimmungsschlüssel für die deutschen Arten der solitären Faltenwespen (Hymenoptera: Eumeninae). Deutscher Jugendbund für Naturbeobachtung, 1994, 54: 90.
8 PEREIRA‐PEIXOTO, MARIA HELENA, et al. Diversity and specificity of host‐natural enemy interactions in an urban‐rural interface. Ecological Entomology, 2016, 41.3: 241-252.
9 WOOD, Thomas; GOULSON, Dave. Aculeate bee and wasp survey report 2015/16 for the Knepp Wildland Project.