HYMENOPTERA > APOCRITA | Aculeata > Formicidae > Formicinae > Formicini > (Raptiformica)

The workers of this species typically have a brighter orange-red colouration compared with wood ants, particularly on the front of the head, mesosoma and legs. The rest of the head may be darker, although variable, and the gaster is slaty grey. The head is broad relative to the gaster when viewed from above. Individuals vary in size, but generally have a body length of 6-10mm. They could be confused with other formicine species, particularly Formica fusca, but the colour should determine although, from my own experience of observing two colonies at different times of the year, the depth of colour varies. I guess it's mainly down to the light but, even from the photos featured here, you can see the difference. The primary characteristic feature of this species though, as long as you have a reasonably clear photo of the face, is the distinct notch in the middle of the clypeus.

Formica sanguinea is a nationally scarce, local, primarily southern ant species, with a disjunct distribution. It is strongly associated with sandy soil habitats and, consequently, is most likely to be found on heathland or in open woodland. However, nests on heaths are unlikely to be far from any transitional zones between the heath and adjacent vegetation, particularly with any pine woodland. They are most active from April to September with alates usually emerging in July.

They are classed as social parasites with queens raiding nests of smaller black ants, usually Formica fusca, killing the resident queen and then using the workers to build a new nest. In established Formica sanguinea colonies, workers regularly carry out ‘raiding parties’ and take larvae and pupae from Formica fusca to rear and boost the numbers of workers in their own nest. This is why it's not unusual to see black ants alongside the larger Formica sanguinea workers. Hence the term 'slave-maker ant'.

Nest sites are usually in the open where there's direct sunlight, typically built around old tree stumps, under large cut trunks or large fallen branches, or under stones. Occasionally they may even be formed directly in the soil and probably topped with an irregular pile of twigs, but nothing like the large thatched nest domes that wood ants construct. Workers primarily search for food on the ground, but may also be seen foraging in low vegetation.

They can be rather aggressive if you encroach too close to the nest, or are standing on one of their trails, and will readily climb up your leg and give you a nasty bite. On more than one occasion I've suddenly been aware that one or two have made their way up inside my trouser legs! It's an interesting observation as you would expect a formicine ant to defend itself by spraying formic acid rather than biting.