There may be a correlation between this significant drop and farmers starting to bring out pesticides, which would explain the current behavior of all orange tips which is noticeably hectic among all observed individuals (both male and female, no mating season yet) and with all outright fleeing towards areas closer to the forest. Granted, they do prefer garlic mustard which won't bloom until May, though so far I failed to observe them feeding on any nectar plant currently available so far.