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The pitfalls of generic field guides
Posted by Graeme Lyons , Thursday, 26 August 2010 12:29
Generic invertebrate guides, such as the Collins Pocket Guide to the Insects of Britain & Western Europe by Michael Chinery are a good way into entomology and it's a great book but beware, there is one major problem. These books never have the complete fauna in every taxanomic group. The problem is confounded by the fact that the percentage of species shown is not proportional to the size of the group, i.e. smaller, more familiar, well-recorded groups (such as butterflies and dragonflies) often have almost the whole species list shown, I think this tends to suggest that other less known groups are also so similarly well covered. They are not. There are 254 species of beetle in Chinery, this is only 6% of the British fauna. I expect flies are similarly poorly represented. A lot of this information is in the book but it's in the order introductions and as such is not obvious.
I see many photos confidently labelled as this species or that complete with Latin name on posts and blogs and it's clear that a 'Chinery ID' has occurred. Sometimes, you might get lucky (the common, big, easy-to-ID species are often included), but ultimately, without getting hold of the full species list for your group, an exhaustive key/field guide and without going through the graft of keying out species, this method of entomology is fundamentally flawed. It's a bit like guessing. The other problem is that incorrectly labelled photos are then readily available on the Internet for other people to see.
I don't want to put people off entomology at all, far from it, but if people are using generic guides like this or websites of a similar nature (and you either fall into this group or you're doing it correctly- you'll know which!), I give the following advice:
- No matter how good you get, you'll NEVER be able to ID everything alone. Especially when you are starting out and you don't know the fauna, it's better to ID things to family or genus.
- Don't spread yourself too thinly to start with, focus on one or two smallish groups and work up to the bigger ones.
- If you don't want to keep specimens, use a microscope or dissect things, butterflies, dragonflies and macro-moths are a good place to start.
- Know the complete fauna, get the species lists, the ID guides and the keys. Do the graft. The smaller and more well known the group, the cheaper and easier this is to achieve but on the other hand, (and in my opinion) less rewarding.
- Find someone who knows more than you. It will stop you from developing 'bad habits' from the start. Listen to their advice and don't reinvent the wheel.
Finally, Ispot is a really great community based website that allows you to upload photos of wildlife (in record format so a grid reference, date and location are required) and a whole host of experts will swoop down on your post and ID it within days. I think this is a great way to learn for all concerned.
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Well put, and useful advice. Thank you for taking the time to write it down.