In many ways the most interesting genus of European orchids, the flowers that almost everyone would recognise as orchids, are renowned for their insect mimicry and many are pollinated by specific insect species conned into trying to copulate with the flower.   The flowers are very distinct from other genera, with usually spreading sepals and petals quite different from the sepals, the lip is frequently characterised by its insect-like appearance.  

PotentiallyOphrys has the largest number of  species of any European genus with well over 200 described by Delforge, equally some authors suggest way less than 50 species and therein lies a problem, species identification!   The insect pseudo copulation mentioned above provides an unusual identification characteristic (studied by Charles Darwin), different species being defined by the insect species that mates with it!   Doesn't help when you are just looking at the flowers.

We do not intend to argue the case for any particular approach other than to say that recently we have used Delforge's book as our field guide  and it makes you look very carefully at plants and pick up small differences (unfortunately these often occur within a single population of the same species), what you then call them is really up to you.

Wherever we have been able to follow Delforge's distinctions we have used his nomenclature on this site, if only to be able to show more photos. However for many species differences are often small and in practice you have to rely on factors other than appearance (such as distribution, flowering time, etc) to separate very similar plants.  At the other extreme there is often such variability within a single population of a given species to suggest more than one species is present.