butterfly legs

[K.J.Caley]

OK, this may be a slightly misguided question, as I haven't seen that
many members of this family, but I have recently been told that some 
snout butterflies (Lybithaeinae), such as the Nettle-tree Butterfly of
Europe possess females which only possess three legs as opposed to the
normal 4 in this group.  Is that really true, or is this someone pulling
my leg(oh dear....pun seen after writing)?

Kevin