Cryptic Wood White

Leptidea juvernica

Leptidea juvernica

Switzerland, May 2018

Leptidea juvernica

Switzerland, July 2009

Leètodea juvernica

Switzerland, May 2012

Leptidea juvernica

Switzerland, May 2010

Leptidea juvernica distribution

Approximate distribution - taken mostly from Leraut, but including
Switzerland, which Leraut omits. I know from the Swiss DNA
barcoding results that the species flies there, in a ratio of roughly
1 : 3 to the wood white.

This page comes with a strong caveat: I have no real idea whether the butterflies shown are cryptic wood whites or not. The problem is, this species was discovered so recently and is so similar to its sister species, the wood white (Leptidea sinapis) and Réal's wood white (Leptidea reali), that satisfactory criteria for determination in the field have not yet been established, if indeed they exist. For the same reason, the distribution, behaviour and ecological requirements of the cryptic wood white are not well known, though there is much ongoing research. Examination of the genitalia is sufficient to separate this species from the wood white but further DNA analysis is required to separate it definitively from Réal's wood white. I do not practise violence on butterflies so do not have recourse to either technique!

As a field criterion, it has been proposed that the postdiscal shadow on the underside hindwing is more curved in juvernica (the cryptic wood white) and reali (Réal's wood white) than in sinapis (the wood white). It is visibly parallel to the curved outer margin of the wing. That is the chief distinction I have been using in Switzerland, where Réal's wood white does not fly. Leraut states that the summer brood of cryptic wood white is ornamented as a spring brood wood white and that for this reason they can often be confidently separated. I'm not entirely sure how to apply this - or perhaps all my identifications are wrong. He also states that cryptic wood white has much reduced orange on the antennae. I haven't yet got this one to work either!

By and large, the cryptic wood white seems to occupy the same kinds of habitats as wood white and use the same foodplants (various vetches, principally of the genus Lathyrus), though Leraut states that it is locally less associated with woods. Like that species it hibernates as a pupa.