Previous to the summer of 1884, Papilio turnus and Pyrameis cardui had been quite rare in Orono, Me., and vicinity, not more than half a dozen of the former and two or three of the latter having been seen each year; but in June of that year P. turnus was so abundant that it was not uncommon to see a dozen or more flying together. In August of the same year fresh specimens of P. cardui were so abundant that in a small piece of red clover, not more than two rods from the house, I captured twenty-five in half an hour, and the numbers were not perceptibly diminished. The next day they were equally abundant, but the following day we had a cold rain storm, after which only a very few poor, faded examples were seen. The next summer (1885) P. turnus was again rare, and not one example of P. cardui was seen by myself, nor by any one in this vicinity. Parasites might have made the difference in the number of P. turnus, but could they have done so with that immense number of P. cardui, or did that storm so effectually destroy them before laying their eggs that there were none the next year, or is it possible that some epidemic attacked them, leaving none to perpetuate the race?