A lot of us nowadays either go abroad on holiday specifically to see butterflies, or try to include some butterfly watching in a family holiday.Europe, and a few countries including USA, Australia, Kenya, Ghana, West Malaysia and Thailand are well catered for, with excellent and affordable field guides available. Travel elsewhere however and you quickly run into problems and will find it very difficult to identify species.
The Butterflies of the World series by Bernard d'Abrera is widely acknowledged as the best resource available to the public, and comprises photographs of all the species held in the British Museum ( Natural History ). Contained within are excellent plates depicting almost every known species of butterfly, with the exception of Skippers. Unfortunately the books are extremely expensive ( around £200 per volume ) and each volume deals with just one family of butterflies from a specific geographical region.
d'Abrera has also produced the single volume Concise Atlas of Butterflies of the World, but this illustrates just a tiny percentage of species from each region, and the species chosen are not typical of those you are likely to encounter.
The out of print single volume Butterflies of the World by HL Lewis is a great deal more useful, as it includes many more species, including Skippers, and the species illustrated are typical of those that the average visitor will encounter. The main problems with Lewis are that the illustrations are not reproduced well in certain editions, and the taxonomy is out of date. You can easily find out the current genus and species name however by entering the Lewis version into LepIndex at http://www.nhm.ac.uk/entomology/lepindex
Even if you cannot identify the species from Lewis, you can usually work out the genus, and then enter that into google, which should with luck lead you to a website illustrating members of that genus.
I travel to the tropics at least once a year, either joining an existing natural history tour, or organising and leading a trip myself. Most of the sites I visit are very poorly recorded, and it's very important to me to get my identifications as accurate as humanly possible, as my records are assimilated into the official species databases for the reserves visited.
Consequently I beg and borrow volumes of d'Abrera from various friends, and if I still run ino difficulties I send images by e-mail to various museums including BMNH and the Smithsonian, who generally can put me in touch with an expert on a particular family or genus who has collected or studied in the country I've visited.
If anyone would like further advice about who to contact, or what books to buy for identifying butterflies from a particular country, please feel free to contact me via ukbutterflies.
Adrian Hoskins