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Bumblebees

Guide to the Field Identification of Highland Bumblebees
for the HBRG Bumblebee Atlas Scheme

This gives a guide to females of the species of Bombus and Psithyrus found in the Highlands and Islands. Prys-Jones & Corbet (1987), Naturalists' Handbook 8, CUP (there is a more recent edition published by Richmond), should be used for confirmation. It has excellent colour plates of all species. Males are easily recognised in many species by having a yellow face, and always by their longer (13 segmented) antennae, blunt abdominal tip, and no sting. Males will key out correctly for some species (marked *), and others can be recognized by obvious similarities to their females once these are known. Normally, males are only produced from late summer. Colours refer to the hairs, unless otherwise stated. Thorax = body section which carries wings and legs. Abdomen = last section.

Key A: Is it a bumblebee (including the parasitic cuckoo bees Psithyrus)?
1a Body not obviously furry. Definitely not a bumblebee!
1b Furry body, short antennae of three segments. Hoverflies or other dipterans which
can be very like bumblebees. If in doubt,
check the length of the antennae.
1c Furry body, long antennae of 12-13 segments, angled. Probably what you want. Key B

Key B: Main bumblebee colour groups
1a Abdomen mainly brown, lacking any clear black or yellow bands. Key C
1b Otherwise. 2

2a Tail (end of abdomen) brown, orange or red. Key D
2b Tail white or slightly off-white. Key E

Key C: Abdomen mainly brown, lacking any clear black or yellow bands.
1a Thorax with a clear band of black hairs between the wing bases. Machair and meadow in the Hebrides, Orkney, and the N and W coasts; rare. This is one of the UKBAP species. All records of this species should be reported, even if it is only suspected. No specimens should be taken. *B. distinguendus
1b Thorax uniform brown (but beware of worn individuals which may seem to show a band of shiny black cuticle). This pair of species can be very difficult to separate. 2

2a Thorax deep foxy red contrasting with pale abdomen. Abdomen with no black hairs at sides. Islands, mainland machair or moorland; rare except on islands. This is very difficult to identify with certainty. Specimens should be kept if it is suspected. B. muscorum
2b Thorax usually browner. Abdomen with variable amounts of black hairs. Common in gardens and many other habitats; absent from Western Isles and Shetland. B. pascuorum

Key D: Tail (end of abdomen) brown, orange or red.

1a Body entirely black, except for the red tail. Widespread now in coastal areas from Nairn to Tain, and west to Strathpeffer. (The similarly coloured B. ruderarius occurs on Coll and Tiree, but there are no recent records from Highland. Its pollen baskets are red, not black.) [Males with yellow face and yellow on thorax.] B. lapidarius
1b Body with at least one yellow band. 2

2a Three yellow bands (2 on thorax, 1 on abdomen, see note 1), tail buff to orange. Western Isles and Shetland only. *B. jonellus sspp.
2b One or two yellow bands. 3

3a Most of abdomen reddish orange. Mainland only, usually on moor or mountain; widespread, but generally uncommon and possibly decreasing. All records of this very distinctive species should be reported. *B. monticola
3b Brown, orange or red on abdomen restricted to the tip. 4

4a Two rather dark brownish-yellow bands, tail pale buff to brown. Very rare in N. Scotland, but has recently colonised the Moray Firth area as far as Cromarty. All records of this species should be reported. *B. terrestris Queens
4b Yellow bands not brownish, that on abdomen divided (queens) or absent (many workers); tail dull orange. Common in gardens and hedgerows in east, scarce in west where it is associated with Rubus spp. [Males with yellow face and more yellow on body.] B. pratorum

Key E: Tail white or slightly off-white

1a Three yellow bands (2 on thorax, 1 on abdomen). See note 1. 2
1b One or two yellow bands. 3

2a Face noticeably long and narrow, tongue very long. Common in many habitats throughout the area, including gardens. *B. hortorum
2b Face only slightly elongated. Common where there is abundant Calluna and Erica, often at high altitude, and on machair. *B. jonellus

3a Two yellow bands, at front of thorax and front of abdomen. This group comprises 4 spp. which are very difficult to distinguish. 4
3b One yellow band, at front of thorax, occasionally some trace of yellow at the back of the thorax. Tail white or yellow with the cuticle showing through as a dark wedge in the middle. This group comprises 4 cuckoo bees which are difficult to separate. 7

4a Yellow of collar extends well below the wing base. Widespread, and associated with moorland and machair; particularly common on the west and on the islands. (This is sometimes considered to be conspecific with B. lucorum, and males can not be distinguished.) B. magnus
4b Yellow of collar extends to, or only slightly below the wing base. 5

5a Yellow on abdomen broken by a band of black hairs (but often this break is not conspicuous). Widespread on the mainland, but scarce and overlooked. [Males with tail white to reddish-brown.] This is very difficult to identify with certainty. Specimens should be kept if it is suspected. B. soroeensis
5b Yellow on abdomen NOT broken by a band of black hairs (but beware of worn specimens whose black cuticle may show through). 6

6a Tail pure white, with no trace of a brown line at the base. Yellow bands bright. The most abundant 2-banded white-tailed bee in the area; absent from the Western Isles and Shetland, but recently found in Orkney. [Males very variable, often very yellow.] B. lucorum
6b Tail white, with a thin brown line at the base. Yellow bands often darker. Very rare in N. Scotland, but has recently colonised the Moray Firth area as far as Cromarty. B. terrestris workers

7a A small yellow mark at each front corner of the white tail patch (often very faint). Common on the eastern mainland, rare in the west and on Orkney. Breeds in lucorum nests. [Males sometimes with yellow tail.] *P. bohemicus
7b No yellow marks in the white area. All scarce, with sylvestris seen most frequently. Specimens should be kept if they are suspected. P. barbutellus, P. campestris, P.sylvestris

Note 1. It is sometimes difficult for beginners to decide whether a bee has 1 or 2 bands on the thorax, as the hinder band (scutellum) appears to run into the abdominal band. The easiest way to tell at first is to see the bee at rest. If there is a band immediately in front of the wing bases, there are 2 thoracic bands; otherwise only 1.

Bumblebee biology - Unlike hive bees, bumblebee colonies are annual. The first bees to appear in spring are the queens which have hibernated after being fertilised the previous autumn. They forage to stock a nest, and lay their eggs. Once the workers hatch, they take over the foraging and the queen then spends most of her time in the nest. Later in the year she begins to lay unfertilised eggs which develop into males, while some of the fertililised eggs produce new queens. The males spend a few happy days drinking and mating with any young queens they find. Eventually, all except the young mated queens die, and these find a burrow to hibernate until spring.

Identification - The common species can be recognised in the field with a little practice. Most reasonably diverse gardens in the area will have at least 4 species regularly (up to 7 in the east), so familiarisation is fairly convenient. The key points are the number of yellow bands, and the colour of the tail. Use the status comments in the key for guidance when learning the common species. For example, 99.99% of bees with brown abdomens on the mainland will be B. pascuorum; a black, red-tailed bee in Inverness is overwhelmingly likely to be lapidarius, but on the west coast you would have to consider ruderarius; a 3-banded bee in a town garden is almost certainly hortorum, but on heather moor is more likely to be jonellus. If you are unsure of the identification, please say so, perhaps explaining your doubts in the comments column, or sending a specimen.

Bumblebees can easily be caught for a close look in a small clear plastic box. This can be very useful when learning the species. Males do not sting, so if you are sure, use your fingers! Even females are usually very reluctant to sting, and with practice can be handled safely.

In some circumstances it may be necessary to take specimens. This should be done sparingly, and for queens only in exceptional cases. Workers and males, especially in the late summer and autumn are more expendable. They can be killed in the freezer, and then dried in air if they are to be kept for an extended time. A freshly dead bee in a closed box creates an astonishingly powerful stench as it decays! Bees are often found dead or dying of disease, trapped in greenhouses, or poisoned by nectar under Lime trees Tilia. Specimens can be sent to me with the usual details as they are collected, or at the end of the season.

Hints for finding bees - Bumblebees are active from mid-March to mid-October. Of the common species, lucorum and pratorum are first to emerge; hortorum and pascuorum last. By October only lucorum and pascuorum are significantly active. Gardens are very good hunting grounds, as are hedges with Raspberry and Bramble (Rubus spp.), and meadows with high densities of pea family plants.

The different species have characteristic favourite forage plants which can make it very easy to find particular species. B. pratorum is very much associated with Rubus thickets, especially in the west where it is quite uncommon. B. hortorum is addicted to Foxgloves. B. jonellus feeds from July onward on Erica and Calluna. Sowthistle Sonchus clumps by the shore are very attractive to terrestris and lapidarius. I have obtained a large number of records of all five species, for little effort, by stopping at suitable plants by the roadside - sometimes not even getting out of the car! In late summer clumps of thistles attract males which sit about in a drowsy stupor. They are worth examining even in damp weather as the bees are often found cold and unable to fly. On one cold, wet July day I went to South Sutor in a square which had NO recent records, and in 20 minutes found 8 species, only one of which was actually flying!

Current coverage of bumblebee mapping in the Highlands and Islands (1988-2000). Shaded dots show 10 km squares with at least one record since 1988. The darker the dot, the more species recorded. A statement of the current records for particular 10km squares (this will be the mapping unit), or for Vice-counties, can be provided if you send me a stamped addressed envelope. Please let me know if you wish to take responsibility for a group of squares so that effort is not unnecessarily duplicated. Records from Lochaber, inland squares of Caithness and Sutherland and upland areas will be especially welcome.
Return records at the end of the season, please, if possible by the end of November, to Murdo Macdonald. 'Tigh nam Beithe', Strathpeffer, Ross & Cromarty IV14 9ET.

Simple colour key to Highland bumblebees (Bombus and Psithyrus)
This is to be used for guidance only. Some males may not match these diagrams.
The top row gives thorax patterns. The second row gives abdomen patterns. Choose the patterns which most closely resemble your specimen, and refer to the key for a list of possible species. Interpret colours flexibly.

         A                              B                             C                      D        

          U                    V                 W                 X                    Y                 Z              

AU - soroeensis, lucorum, magnus, terrestris
AV - Psithyrus spp.
AW - male lapidarius, ruderarius, worker pratorum
AX - monticola
AY - pratorum, terrestris
BU - jonellus, hortorum
BV - Psithyrus spp.
BW - male lapidarius, ruderarius
BX - monticola
BY - male pratorum
BZ - distinguendus
CZ - muscorum, pascuorum
DW - lapidarius, ruderarius