1. DISTRIBUTION
Coelioxys elongata [1] occurs at the coast, the higher sandgrounds and in the hills [3] and is a rare species in the Netherlands [2].
2. BEHAVIOUR
2.1. ACTIVITY
The species is active from May to September [3].
2.2. DEVELOPMENT
Coelioxys are broodparasitoids on primarily Megachile species. The Coelioxys species can therefor be found where its hosts nest, ie. in plant stemms or old wood borings [3]. Since a number of hosts aso will use artificial nest blocks like bee hotels, they can be found on those too.
They produce one generation per year [3].
When the female has located the host’s nest it will enter it abdomen first and deposit an egg in the rear wall of the brood cell [3].
The first and second instar larvae are tied to the egg shell [3]. The first instar will develop within twelve hours into the second instar [3]. The second instar has jaws it can use to kill the host larva. The third instar moves freely through the brood cell and shows predatory behaviour. It will consume the host egg or larva or potential other Coelioxys larvae present in the nest cell [3]. The third, fourth and fifth instars eat the pollen from the host brood foodsupply [3].
2.3. NECTAR PLANTS
The adult animals can be found on flowers where they drink nectar. Coelioxys bees have a long tongue and visit only flowers in which the nectar lies deep.
C. elongata uses the following nectar plants in my garden (own observations, the gender is shown on the specific flower):
| Cabbage family (Brassicaceae) | – Dame’s rocket (Hesperis matronalis), ♂ |
| Rock rose family (Cistaceae) | – Halimium umbellatum, ♀ |
| Sage family (Lamiaceae) | – Oregano (Origanum vulgare), ♂ – Salvia sp., ♀ |
| Legume family (Leguminosae) | – Broad-leaved sweet pea (Lathyrus latifolius), ♀ |
3. PARASITIC RELATIONS
MEGACHILIDAE are the primary hosts of C. elongata [3,4].
The following hosts mentioned in the literature can be found in the Netherlands:
| Bees (MEGACHILIDAE) | – M. centuncularis [3,4,5] – M. circumcincta [3,4] – M. leachella [3,4] – M. ligniseca [3,4] – M. maritima [3] – M. pyrenaea [3] – M. willighbiella [3,4,5] |
In the garden the following hosts occur regularly or have been sighted:
| Bees (MEGACHILIDAE) | – M. centuncularis [3,4,5] – M. leachella [3,4] – M. willighbiella [3,4,5] |
4. IDENTIFICATION
The male as well as the female Coelioxys bees are difficult to separate and some species are only identifiable by the genitals (ie. killing them), which is among others true for the male C. elongata.
♀
1. Coxae frontal legs with thorn [4]
2. Tergite 6 never points upwards [4]
3. Hairbands tergites 2 and 3 uninterrupted [4]
4. Gradulus uninterrupted [5]
5. Hairbands sternites 2 to 4 uninterrupted [4]
6. Sternite 2 shiny and densely punctated [5]
This is a secondary character (see discussion with bee expert Albert de Wilde). In this specimen the seternite is not densely punctated and looks more like the character of C. inermis. However the next character on sternite 4 is more important and matches C. elongata.
7. Sternite 4 sideways of the middle dull and densely punctated [4,5]
8. Sternite 5 caudally narrowed [4]
9. Sternite 5 lightly dented [4,5]
This character apparently can also be found on C.inermis (see discussion with bee expert Albert de Wilde), which makes it unreliable.
10. Sternite 6 with two teeth at the sides [4,5]
11. Sternite 6 long and narrow, abruptly narrowed at the end into a long tooth [4]
12. Upper jaw bend, without a clear angle between the upper and lower halves
♂
Males cannot be separated from C. inermis and C. mandibularis without investigation of the genitals.
- Coxae frontal legs with thorn [4]
- Tergite 6 with six thorns [4,5]
- Edge sternite 4 complete and rounded, sometimes with a slight indentation [4]
- No tooth between thorns sternite 6 [4]
- Spurs hind leg light brown [4]
- Temples as wide as eye with or narrower, tergite 2 denser punctated at base than on rest [4]
- Genostylus apically somewhat enlarged [4]
- Hairbands tergites 2 to 5 uninterrupted in fresh specimens [5]
- Hairbands sternites 2 to 4 uninterrupted [5]
Literature
1 Nederlands Soortenregister2 Waarneming.nl
3 Peeters, T.M.J., H. Nieuwenhuijsen, J. Smit, F. van der Meer, I.P. Raemakers, W.R.B. Heitmans, C. van Achterberg, M. Kwak, A.J. Loonstra, J. de Rond, M. Roos & M. Reemer 2012. De Nederlands bijen (Hymennoptera: Apidae s.l.). - Natuur van Nederland 11, Naturalis Biodiversity Center & European Invertebrate Survey - Nederland, Leiden.
4 NIEUWENHUIJSEN, Hans. Determinatietabel voor de bijen van het genus Coelioxys in Nederland. Bzzz/HymenoVaria, 2010, 1.1: 32-35.
5 Rowson, R. & Pavett, M. 2008. A visual guide for the identification of British Coelioxys bees. 7pp. Privately published, Cardiff, UK.
