What are the Chrysomelidae?
The Chrysomelidae are the seed and leaf beetles and may be familiar as the medium-sized shiny metallic beetles seen on mints, docks etc., the 'flea beetles' named after their small size and jumping ability, or the flattened, often green, 'tortoise beetles'. However, the group is a little more varied than this and includes the following three families:
- Chrysomelidae. The majority of leaf beetles, including the subfamilies Donaciinae ('reed beetles', Bruchinae ('seed beetles'), Galerucinae (encompassing the 'flea beetles') and Cassidinae ('tortoise beetles').
- Megalopodidae. 3 species, all in the genus Zeugophora.
- Orsodacnidae. 2 species, both in the genus Orsodacne.
Together these currently cover 281 species, a number which changes now and again with new discoveries and updated taxonomy.
Why record them?
As with any species group, biological records allow us look for changes in distribution, and to some extent abundance. This is important when seeing how a rare species is doing, how a newly-introduced species might be spreading or whether a previously common species is declining. Information such as this is important e.g. when managing for conservation, doing ecological research, looking at land use policy/planning, or keeping track of invasive potential pest species - there are many ways in which the information from such records can be used, and volunteer recorders are an essential part of this. The scheme aims to collect accurate records from as many recorders and as much of the UK as possible.
How to identify them
This can be tricky, at least at first. Some are straightforward with clear patterns or colouring, while others are relatively familiar like the 'Lily Beetle' Lilioceris lilii (even if it's not popular with gardeners), or the colourful and charismatic Chrysomela populi. Some can be difficult to separate even with experience, such as some of the 'flea beetles', but don't be put off - even the experts had to start at the beginning once upon a time, and practice makes perfect - start with the easier ones and gradually expand your knowledge. If you get stuck, that's fine - you should be able to get help via the recording scheme, or come back to it later, and it's better to be sure than to guess. An important part of identification is finding books and other sources to refer to - until recently there was no single guide to all British and Irish species (many need closer examination than an external photo can provide), but there is now an affordable key available here (Hubble, 2012) as well as the Atlas (Cox, 2007) which gives more descriptive detail as well as distribution maps. Details of both are given below under 'the essentials'.