Horseshoe Ladybird  Clitostethus arcuatus

This is an elusive species. Mark Hows and I travelled to Abney Park, N. London (twice), Kidderminster, Worcs and Royal Tunbridge Wells, Kent on unsuccessful trips to find Horseshoe Ladybird. Each site consisted of shaded woodland with an Ivy and/or Holly understory.

I eventually found one on my local patch at Fishers Green, Essex on 7th October 2019.

I found my second in an ivy covered hedge in Upshire, Essex on 17th September 2020.

Identification        Length  1.2-1.5mm

This is a cream and brown species, although the intensity of the markings can vary. The horseshoe marking seems to be consistent making this a distinctive species when seen well.

There is often a second fainter horseshoe mark, similar to a double rainbow, towards the rear of the wing cases.

This is a very small species, so could easily be overlooked. When I finally found one, I was very sure what it was sitting stationary in my umbrella but I was not 100% certain until I had taken a photo and checked the image on the back of the camera monitor (a hand lens would also do this task).

Fishers Green, Lee Valley, Essex
Fishers Green, Lee Valley, Essex
Fishers Green, Lee Valley, Essex
Photo by Mark Hows
Fishers Green, Lee Valley, Essex
Upshire, Essex
Upshire, Essex
Upshire, Essex
Upshire, Essex
Upshire, Essex
Fishers Green, Lee Valley, Essex
Upshire, Essex
Upshire, Essex
horseshoe ladybird
Upshire, Essex

Habitat

This has traditionally been considered a very scarce species, but records are currently increasing. This is probably due to a better understanding of the habitat requirements of this species.

An important factor is knowing that the Horseshoe Ladybird feeds on Whitefly Aleyrodidae and so habitats need to contain this prey species.

 

 

Whitefly on Ash
Royal Tunbridge Wells, Kent

All the sites I have visited looking for this species were in shaded woodland with a lot of understory, especially Holly and Ivy, were it can be found overwintering.

The one I found at Fishers Green, Essex was beaten from Ivy growing on a tree trunk in a small but dark shaded patch of woodland.

Ivy covered tree trunk    Fishers Green, Lee Valley, Essex
Ash tree with Whitefly   Royal Tunbridge Wells, Kent

No Horse-shoe Ladybirds were seen on this visit, although they had been reported shortly before.

Whilst this species is often reported wintering in Holly and Ivy, in autumn it has been reported feeding on Whitefly on Honeysuckle in the same areas.

They can also be found in gardens, although I have not managed this yet. Again the associasion with Whitefly is important and it has been reported with this species on Greater Celendine Chelidonium majus as well as the evergreen shrub Viburnum tinus.

Looking at the distribution of this species on the NBN Atlas shows a few distinct clusters. This is probably observer bias and shows the areas where a recorder has discovered the skill set to locate this species. 

The other possibility is that this is not a very mobile species and it does have a patchy distribution. Hopefully as more people search for this species we will discover its true distribution. 

Look-alike Species

When seen well Horseshoe Ladybird is unlikely to be confused with other inconspicuous ladybirds. 

However when searching for this species in typical habitat with a beating tray it is common to find numerous small early instar true bugs. Whilst these are a very different shape, many of them are the same size and cream and brown colour as Horseshoe Ladybirds.

Care needs to be taken not to overlook Horseshoe Ladybirds amongst these. 

Early instar bug with similar colouring to Horseshoe Ladybird

Copyright Andrew Jewels 2019-2020