Arboreal and Meadow Ladybird Comparison
This species pair has a reputation for being easily confused but I consider the vast majority to be identifiable by examining the upper parts. The light and dark markings on the wing cases of each species show up best on photographs of live specimens taken in outside natural light. The subtle tonal variation does not show up well on microscope photographs taken in doors or on pinned specimens in harsh studio lighting.
Habitat : Arboreal Ladybird
Pine trees, ivy and evergreen garden shrubs.
Habitat : Meadow Ladybird
Grassland, also nettles, thistles, edges of ponds, ditches and sometimes in gardens.
Background Colour : Arboreal Ladybird
Mostly oak brown to deep chestnut.
Occasionally a paler orangey brown.
Background Colour : Meadow Ladybird
Mostly pale yellowy buff to oak brown.
Some deep chestnut, even blackish.
Pronotum sometimes paler than wing cases.
Pale Markings : Arboreal Ladybird
A pale curved stripe across the upper wing cases.
These usually extend down the centre of the wing cases as a pair of tramlines.
Wing case tips usually grey.
Pale Markings : Meadow Ladybird
Many are uniform and lack paler markings.
Often shows a neat pale outer edge to the wing cases.
Dark Markings : Arboreal Ladybird
The dark markings form a shield shape with two vertical lines reaching near the top corner, an anchor shape in the lower centre and a pair of tooth shaped marks.
Dark Markings : Meadow Ladybird
Some are uniform and lack dark markings.
Often shows a dark U-shape marking on the rear wing cases with one vertical line extending half way up each wing case.
Variable dark patch at the top of the wing cases behind pronotum.
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Pronotum : Arboreal Ladybird
Strongly curved on the corner sometimes forming a right angle and the rear edges are often straight and nearly parallel sided.
Pronotum : Meadow Ladybird
The sides are gently curved, often still widening as they reach the wing cases, although some have an angled corner similar to Epaulet Ladybird.
History of Recording
Meadow Ladybird is a common native species of grassland habitats that has been well recorded for a long time.
Arboreal Ladybird was recorded in the UK for the first time in Surrey in 1996.
Early records relied on identification criteria based on the scientific literature, often including the dissection and microscopic examination of the male genitalia.
Arboreal Ladybird quickly gained a reputation for being very difficult to separate from Meadow Ladybird.
This reputation has continued to the current day and is harming the accurate recording of Arboreal Ladybird, which is now one of the commonest species of ladybird in large areas of southern England.
Specialist coleopterists tend to record this species once or twice in a recording area and having collected a few specimens move on to the many other interesting beetles available.
Wildlife enthusiasts sometimes find and tentatively identify Arboreal Ladybirds but then find the levels of proof required off putting or are steered towards Meadow Ladybird as a more likely identification.
Between 1996 and 2018 a total of 216 records of Arboreal Ladybirds were submitted to the NBN Atlas, an average of just under 10 a year.
In 2020 I submitted a total of 318 records of Arboreal Ladybirds, mostly on lockdown walks close to home. This species is severely under recorded.
In 2021 I submitted a further 444 records, with another 407 in 2022.
Prosternal Keel
The prosternal keel has become the main feature used to identify this species pair, largely by default as it is a binary feature which works well in a dichotomous key.
The prosternal keel is located on the underside between the front pair of legs.
This feature is why The Field Guide, Roy and Brown 2018 used the names Pointed-keeled Rhyzobius and Round-keeled Rhyzobius for these two species.
However, I find this feature unreliable.
Meadow Ladybird has a prosternal keel described as a straight sided narrow triangle with a pointed top.
The shape is similar to The Shard building in London.
Arboreal Ladybird has a parallel sided mid section, a rounded top and the lower section widening.
This resembles a narrow bell shape.
The reality is more complicated than this.
Whilst some Arboreal and Meadow Ladybirds show the expected classic shapes, many can be inconclusive and intermediate. There is a lot of leeway with these, with observers using subjective interpretation.
More significantly Arboreal Ladybird can often show a pointed tip to the classic bell shape.
If these are routinely mis-identified as Meadow Ladybird then three issues arise:
a) Arboreal Ladybird maintains its reputation for being rare.
b) The identification criteria of the two species become confused, adding to the belief that
they are unidentifiable using visible features on the upper parts.
c) The habitats frequented by each species also become confused.
Wing case markings versus keel shape
I have been using a combination of subtle but consistent wing case markings, alongside pronotum shape and habitat, to distinguish these two species, which I refer to as Arboreal and Meadow Ladybirds.
Other recorders prefer to rely on the keel-shape, with out referring to wing case pattern or habitat. The vernacular names Round-keeled and Pointed-keeled Ladybirds cover this identification process.
The scientific names Rhyzobius chrysomeloides and Rhyzobius litura refer to slightly different groups depending on which system is used.
Using the keel shape the two species are separated along the vertical line A-B.
Using wing case markings the two species are separated along the horizontal line C-D.
Group 1 consists of individuals that show the features of Arboreal Ladybirds and have round-keels and these are classic chrysomeloides, accepted by all.
Group 4 consists of individuals that show the features of Meadow Ladybirds with a pointed-keel and these are accepted by all as litura.
Group 3 consists of individuals that show the features of Meadow Ladybirds with a rounded-keel. I would call these litura, whilst the keel-shape would identify them as chrysomeloides.
Group 2 consists of individuals which show all the features of an Arboreal Ladybird, but which have a pointed-keel.
I call these chrysomeloides, whilst the keel shape would key them out as litura.
Both of these contrasting identification systems, wing case markings or the keel-shape are self-reinforcing.
An independent review of the identification features for this pair of common species is now needed.
Habitat
Scientific keys tend to avoid mention of habitats, but in the case of Meadow and Arboreal Ladybirds understanding their range of habitats is important.
Both species can overlap in gardens and in scrubby hedgerows, particularly in late season seeding thistles, burdocks, black horehound and similar woody herbage.
However, each species has a specialist habitat and surveying these is the best way to become familiar with the variation of each species and learn how to distinguish them from each other.
It also provides an opportunity to build up a reference collection of photographs of live individuals taken in the field.
Open grassland, well away from shrubs and trees, is the best area to search for Meadow Ladybird, with out the presence of Arboreal Ladybird to confuse matters.
I have swept a total of 146 Meadow Ladybirds from grassland and they have all looked like Meadow Ladybirds, with no features suggesting Arboreal Ladybirds.
This figure is quite low as my recording area is on clay soils; chalk and sandy soils are likely to produce higher numbers. Also, I spend a lot more time beating than sweeping.
Most grassland areas with abundant 16-spot Ladybirds will also produce Meadow Ladybirds.
Ideal Meadow Ladybird habitat: Open grassy meadow with nettle patch
Arboreal Ladybirds can be abundant on ivy covered tree trunks in deeply shaded woodland and can be found in this habit throughout the winter.
I have found c.1000 Arboreal Ladybirds and only two Meadow Ladybirds in this habitat.
The vast majority, have been easy to identify.
A few pale individuals are a bit tricky to categorically separate from Meadow Ladybird but as of 2020 I think I have found reliable criteria to identify even the palest specimens, although I am still refining the process.
Ideal Arboreal Ladybird habitat: Ivy covered tree trunks in shaded woodland.
Arboreal Ladybirds are also common in pine trees and I have never recorded Meadow Ladybird in this habitat.
However, other observers have reported Meadow Ladybird in pine trees.
At May Day Farm, Suffolk, I have beaten Arboreal Ladybird from small pine trees in a grassy clearing, whilst sweep netting Meadow Ladybird from the adjacent grassland. So the two species occur alongside each other and could co-inhabit.
There is no substitution for spending time in the field beating and sweeping to gain familiarity for these two species and to develop an understanding of their differences.
Field Experiments and Observations
The best way to gain experience of these two species would be to concentrate on sweeping good open grassland habitat in late summer/early autumn for litura, followed by a winter of beating ivy in dense woodland for chrysomeloides.
This would allow the building up of a data base of photographs taken in the field (or collected specimens if preferred).
This data base could then be used to answer a simple question. Do the specimens in the two different habitats contain a mix of individuals showing characteristics of Arboreal and Meadow Ladybirds or do the specimens in the grassland all resemble Meadow ladybirds and the ivy contain specimens that all resemble Arboreal Ladybirds?
The next step is rather more complicated and slightly beyond my skill set.
A full comparison of individual specimens covering:
habitat; ivy woodland or grassland
keel-shape; pointed, rounded or intermediate
pronotum shape; curved, parallel-sided or intermediate
and wing case markings; Meadow or Arboreal, but also as many individual features as possible.
A full statistical analysis of all the variables would then be required.
Conclusions
One possible outcome would be that only Pointed-keeled Meadow Ladybirds occur in grassland and only Round-keeled Arboreal Ladybirds occur in the ivy woodland.
I think this is unlikely to be the case but this would be the ideal scenario as the keel-shape could be used for museum specimens and the wing case markings for field work.
Another possibility would be the grassland habitats containing only Pointed-keeled Ladybirds showing a mix of Meadow and Arboreal wing case features and the woodland ivy containing only Round-keeled Ladybirds showing a mix of Meadow and Arboreal wing case features.
This result would rule out the possibility of in the field identifications based on wing case pattern but my field studies over the last ten years suggest that this scenario can be ruled out.
A more complicated variation on the above scenario would be a complete overlap of habitat, wing case markings and keel-shape making this species pair unidentifiable without dissection but again my own observations discount this possible result..
The result that I think is the one that other independent studies would replicate and tallies with my studies is:
grassland habitats containing Meadow Ladybirds with the majority showing pointed keels but a smaller proportion with round keels
and woodland ivy containing Arboreal Ladybirds with the majority showing round keels but a
smaller proportion with pointed keels.
If this proves to be the case then a simple thought experiment can help work out whether the keel-shape or wing case markings are the most logical identification system to use.
If using the wing case marking then the conclusion is that Rhyzobius litura is a species that mostly frequents grassland and has a suite of variable but distinctive markings, whilst Rhyzobius chrysomeloides is found in ivy woodland and other similar habitats and also has a suite of variable but distinctive markings. The keel shapes of each species are often distinctive but can be unreliable and lead to mis-identifications and need to be used in conjunction with the other features, if at all.
This is a simple and elegant solution to the treatment of two closely related but separate species.
If using the keel-shape things quickly get very complicated.
The main population of litura has the markings of Meadow Ladybird and inhabits grassland whilst a smaller sub-population inhabits ivy woodland and mimics the markings of Arboreal Ladybird.
The main population of chrysomeloides has the markings of Arboreal Ladybird and inhabits ivy woodland whilst a smaller sub-population inhabits grassland and mimics the markings of Meadow Ladybird.
This is scientifically and biologically extremley implausable and can be discounted.
Museum Specimens
Whilst the purpose of this website is to promote the field identification of inconspicuous ladybirds it important to note that insect collections in museums are a very important resource and many insect species cannot be identified without collection and microscope work. However, I feel that the inconspicuous ladybirds have traditionally been placed in the wrong category, with keys that have an over emphasis on microscopic features, when most species can be easily identified from a decent photograph.
Museum specimens of litura collected before the 1990s (before the arrival of chrysomeloides) could be an interesting subject for study.
If the wing case marking are reliable then they should all resemble Meadow Ladybirds.
If both species have a complete overlap of wing case features and only the keel shape can distinguish them then some early collected specimens should show the wing case markings of a typical Arboreal Ladybird.
Early litura specimens may not have had their prosternal keels checked as there was only one species of Rhyzobius in the UK at the time. Looking at these keel shapes would be interesting. If the keel shape is reliable and consistent then they should all show the typical pointed shape shown by Pointed-keeled Ladybird. If any show the typical shape of Round-keeled Ladybird, then this would suggest that either the keel shape is unreliable or chrysomeloides was in the UK earlier than realised living alongside and mimicking Meadow Ladybird.
Final Thoughts
The majority of Arboreal and Meadow Ladybirds (about 95%) are easily identified from a photograph of the upperparts, or close examination with a hand lens.
Some (about 5%) can be a bit tricky and can cause confusion without experience of the full range of variation for each species.
A very small number (less than 1%) might not be identifiable on current known criteria.
As more people start to look at the field characteristics of live specimens in the field, the better we will understand the variation of the trickier specimens.
Meadow and Arboreal Ladybirds are similar to 10-spot Ladybirds, as they have a wide range of forms that can be confused with other species by inexperienced observers but can mostly be identified by a good quality photograph.
I still occasionally get caught out when making a quick identification between 10-spot, Cream-streaked and unusually small Harlequin Ladybirds, as they all have overlap colour forms. A careful check of a photograph usually sorts out the situation.
Despite this possible confusion, 10-spot Ladybird is considered acceptable by photograph because it is a common species.
Arboreal Ladybird is not universally considered acceptable by photograph because it is a rare species.
However, my records contradict this assumption.
I have submitted all my 10-spot Ladybirds records since I started recording about a decade ago.
My submitted record totals to the end of 2024 include:
Arboreal Ladybird: 2166 records
Forestier's Ladybird: 164 records
10-spot Ladybird: 174 records
Meadow Ladybird: 149 records
This demonstrates just how common Arboreal Ladybird can be, at least in some parts of the SE of England.
At present, Arboreal Ladybird is under represented in the recording process. This is due to concern that a few stray records may enter the system.
The unintended consequence of this is that all published lists of the commonest ladybird species in the UK are compromised by the absence of one of the commonest species from the data set.
Searching for and submitting records of Meadow and Arboreal Ladybirds is a relatively easy and rewarding way to become involved in the world of inconspicuous ladybirds and will help in the recording process of this fascinating and controversial species pair.