Boisterous Wool Carder Bees

This summer, I discovered a colony of wool carder bees in the Sensory Garden beside the River Witham and these characterful little creatures became the focus of my lunchtime walks for much of the rest of the season. The photographs and slow-motion videos below were all taken in this garden over the course of the summer.

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Wool carder bee feeding on lamb’s ear

The wool carder is a striking bee – chunky and robust with sporty yellow markings down the sides of the abdomen which is tipped with five spikes in the males. They are in the megachile family – alongside the leafcutters – but are the only representative of the Anthidium genus to be found in the UK. More broadly, they are one of the 250 or so solitary bee species in the UK. They are common in England and Wales but are just starting to make their appearance into Scotland.

The name ‘wool carder’ is an intriguing one which relates to an even more intriguing behaviour. ‘Carding’ is a mechanical process which involves disentangling, cleaning and preparing fibres for processing, and the word originally comes from the latin ‘carduus’ relating to teasels or thistles which were historically purposed for the task. In this context, ‘wool carder’ relates to the behaviour of the female bees who shave plant hairs and fibres from leaves and stems. They gather these fibres into a bundle and take them to their nest site – often aerial holes and crevices as well as hollow plant stems and bee hotels – and use them to line the nesting tubes.

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Male wool carder bee resting on the ‘wool’ of a lamb’s ear leaf

The wool carder bees forage on a range of species, specialising in those in the deadnettle and pea families such as betony, woundwort, mint, balm, loosestrife, toadflax and restharrow. This study from Kernowecology found that in native vegetation, marsh woundwort and purple toadflax were the most commonly used flowers for nectaring whilst greater bird’s foot trefoil was most commonly used as a pollen source. They advise that planting those two species together is successful in attracting these bees.

However many people will encounter the bees, as I did, on a garden plant and Stachys byzantina seems to be one of the most popular for this species. This plant is one of the woundworts which is a member of the deadnettle family which the bees favour for nectaring, whilst also having perfect ‘wool’ for the females to gather for their nest tubes – the plant is not known as ‘lambs ear’ for nothing! This combination of the bees’ two key requirements makes them irresistible to the female bees and this is something which the male bees take advantage of.

The male bees are larger than the females, and are highly territorial. I spent many lunchtimes watching them patrol a patch of lamb’s ear, waiting for the females to arrive. Once a female landed to nectar, the male would pounce upon her for a swift and unambiguous mating – see video below – before leaving the slightly startled looking female to continue visiting the flowers.

The males would regularly rest in a spot of sunshine before upping and patrolling the flowers in search of females or rivals.Interestingly, one might expect the male bees to limit their attentions to other male wool carders who represent a direct rival, but instead they will attack and chase away any other bees including honey bees and much larger bumblebees – see videos below. This is thought to be a mechanism of maximising the value of their territory, and thus making the plant more enticing to female bees. They will grapple with these other bees and pull them off the flowers and sometimes pursue them to the ground. The spikes in the base of the thorax are then seen to be not simply for show – the male wool carders use these aggressively, capturing their enemy between their curled thorax and the spines in order to inflict damage.

This behaviour is fascinating to watch, and seemed of little concern in the garden as the wool carder males limited their attention to their patch of lamb’s ear, leaving other bees safe to forage on the multitude of other flowers nearby. However this aggressive behaviour gives significant cause for concern when the bee is invasive in other countries such as the US and New Zealand. Their distribution close to ports in NZ indicates that they may have come across in ships, whilst they have been detected in various parts of the USA since 1963 and are making an appearance across the country, establishing now in western USA. Kelsey Graham is studying the effects of the wool carder as an exotic species on the native US bee populations. As in the UK, there is considerable concern in the USA about the decline of native bees including bumblebees and other solitary bees species such as the Osmia. The impacts of the exotic wool carder bees in the US relate in part to competition for nectar as they are sharing a finite resource with the native species, but particularly relate to the aggressive behaviour of the males in attacking the native species. Kelsey identifies that the chemical changes induced in the plants by the ‘carding’ of the females releases chemical signals which attract further wool carder bees. Native US bumblebees seem most likely to be attacked, and Kelsey’s research has found that this leads to these bees avoiding areas where the wool carder bees patrol, thus reducing the availability of foraging resource to the native bees. You can read more about Kelsey’s research here.

The wool carders are a summer bee, flying from June – August, and visiting the Sensory Garden in September seems somewhat lacking without the antics of this boisterous and charismatic bee. Kate Bradbury wrote a wonderful piece in the Guardian about watching these bees in her newly created wildlife garden where they arrived in less than a year, so I am hoping that the already-established lamb’s ear in the garden of the house we have just moved to will provide this spectacle on our doorstep next summer!

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Wool carder bee in flight

Red-eared Terrapin in Grantham Canal

I had something of a surprise when out walking along the Grantham Canal at the weekend. A friend posted a cracking photograph of a mink on twitter (and now on her blog which you can read here) which was seen along the stretch between Harlaxton and Denton. This is a non-native species and can cause serious damage to the ecosystem through their predation on native species of fish, birds and water vole. However, it is argued that, as these are all food sources for the native otter, the non-native mink is filling a currently vacant ecological niche for a semi-aquatic carnivorous mammal in our waterways. Whilst the grey squirrel competed with the native red in a similar way to the detriment of the reds, there is good evidence to suggest that the re-colonisation of a watercourse by otters will lead to the displacement of the smaller mink and so the native species would win out in the end. Whilst we wait, and hope, for otter to continue their spread through our native watercourses, the mink could be seen as its understudy. They can however cause serious problems in some locations, especially where they prey upon the eggs of sensitive bird species, and eradication programmes are in place in a number of locations to remove them. I have only once seen a mink along the canal, on the stretch by Woolesthorpe some years ago, and was keen to see another.

I was scanning the edge of the canal as we walked along and was taken aback to see a completely different non-native species instead – a red-eared terrapin (Trechemys scripta elegans) basking out of the water on a log! This individual was around 30-40cm which is adult sized. These reptiles, originally from the Americas, were popular pets in the 1980’s and 1990’s following the Teenage Mutant Ninja Turtles on childrens’ TV. They tended to out-grow their confinements and many of the more irresponsible owners simply released them into the wild. They can live for several decades and so this specimen could have been in the canal for a long period of time. The sale of these species does continue however so it could be a more recent arrival.

Red eared terrpin in British canal - Grantham Canal, Lincolnshire, UK

The terrapins feed on aquatic invertebrates and amphibians and so, like the mink, are a cause for concern in British waterways. Whilst the mink is quite able to breed and spread throughout the UK, there is less concern about the terrapins at present – they require around 100 days of >27 degrees or 60 days of >30 degrees for the eggs to successfully hatch and the young to develop which is rarely achieved in a British summer. This puts the terrapin into a different category to the mink – whilst they are not desirable, they are at least naturally controlled by the climate and they should not increase under their own steam. This means that there is not currently a requirement to control them in the wild; rather better controls on the sale of these species should ensure that they do not continue to be a problem once the individuals at large have died out naturally. That said, increased temperatures as a result of climate change could see this whole situation change! A juvenile was spotted Regent’s Canal in London last year and this caused concern that they might have found conditions warm enough to breed in our unusually hot summer.

The individual spotted in Grantham canal may even be the only one present – if no others were released alongside it. There is a record of an European Pond Turtle in the canal from 2006 which may be a misidentification of the same individual I saw, or it could be that this non-native species is also present along the waterway.

Next time you are walking along the canal, keep an eye and you might just spot something unexpected!