Since my last post on this subject, His Imperial Majesty has largely (but not exclusively) emerged from hibernation, and larvae on some early-leafing trees have commenced feeding - only to stop again due to the onset of foul & abusive weather which appeared, predictably, the moment the entire Purple Empire was included in official Drought Zones.
I was very much under the belief that 2012 would only see a poor adult emergence, as a knock-on from a very poor egg lay last year. However, a fascinating German book (Gabriel Hermann, Searching for Butterflies in Winter. 2000. Books on Demand, GMBH, Nordestedt - in German with a rather poor computer-generated English translation) offers significant hope, stating (I paraphrase the translation):-
'Amazingly, according to the author's observations, ... it appears that flight seasons following winters with very low larval populations regularly see good emergences' (end of my paraphrase). He continues: 'A possible reason for this could be that tits quickly learn to find young caterpillars in winters with very high caterpillar density and thus cause very high losses.' He terms this 'tit learning effect'.
Now, losses of wild hibernating larvae during the previous two winters (to assumed tit predation) were ca 63%. This last winter, with a much smaller sample - as larvae were very scarce - only 25% were lost. So hopefully Herr Hermann's theory will redeem the 2012 season... .