I visited Prawle on the south Devon coast five times last summer searching for the stunning long-horned bee Eucera longicornis. This rapidly declining bee has one of its few remaining strongholds here. At the end of May over 20 males were observed patrolling the nest sites along the base of a low clay cliff and over a patch of bird’s-foot trefoil flowers.
During my next visit on 14 June several females were busy digging out nest burrows in the same area. The males had spread out further afield with some in gardens in the nearby village of East Prawle. The dry spring and a lack of grazing on the adjoining meadow led to a superabundance of clovers and vetches. This was probably due to the more vigorous grass growth being suppressed earlier in the season allowing the legumes more light and space to flower profusely. During the visit a Six-banded Nomad bee Nomada sexfasciata made a brief visit to the nest colony. This bee is a cuckoo in the nests of the long-horned bees and is now one of the UKs rarest bees being currently known only from this short stretch of coast at Prawle. There are just a handful of sightings each year and the bee is considered to be in danger of extinction in the UK.
On 6 July I spent three hours on a sunny, warm afternoon observing the nesting colony with Buglife volunteer Catherine Mitson. We marked three of the nesting females in an effort to find out a little more about their foraging behaviour. One female returned four times and took between 23 and 44 minutes to collect a full load of pollen for her nest. The other bees took between 1 hour and 1 hour, 24 minutes to return. I hope to conduct more work on this behvaviour in 2018. Although the sample was very limited it seems to suggest that the bees are travelling some distance to collect pollen.
We suspected that the bees were visiting a large patch narrow-leaved everlasting pea Lathyrus sylvestris present a few hundred metres to the east of the colony. This and other Lathyrus peas are known to be favourite forage plants for this bee. Despite many hours spent observing and sketching the bees on my next visits I didn’t see any of the marked bees. A much larger sample would be required to make this work more feasible and try and gain an understanding of how far these bees are travelling to collect pollen for their nests.
The long-horned bee season continued well into July, the last males were seen on 6th but many females were noted on 23rd during Steven Falk’s bee identification course. With good weather during the flight season and an abundance of forage plants it is hoped that the long-horned bee and its Nomad has a good year. I am already looking forward to meeting up with one of my favourite insects again this year.