1911] The Ottawa Naturalist. 101 



must indicate that the butterflies fly as late as u October. In 1902, 

 at Lake Lachigan, the butterflies were common on September - 

 1st in all conditions, from freshly emerged specimens to those 

 which had scarcely sufficient fragments of wings left to enable 

 them to fly, but from the larvae which I brought home, although 

 some turned to pupae early in September, the butterflies did not 

 appear till the end of November and through December and 

 January. They were, of course, kept indoors in a warm room. 



In species which have more than one annual brood it is 

 difficult to define the dates of appearance and disappearance of all 

 but the first, but judging by my experience it would be absolutely 

 impossible to state how many broods there were annuallv of 

 F. tarquinius. Like several others among our butterflies, Colias 

 philodice for example, it appears to keep on laying eggs, which 

 continue to hatch into larvae, which continue to eat until one day 

 becomes too cold for their existence or that of their food supply, 

 and every stage is wiped out except the one which Nature ordain- 

 ed should pass the winter. In F. tarquinius the chrysalis hiber- 

 nates, and again Nature has in some way arranged that the 

 butterflies do not all appear at once, a most necessary provision, 

 as the supply of food for the young larvae would soon be exhaust- 

 ed if the eggs were laid and hatched about the same time. Not 

 only do the butterflies appear extended over a considerable period 

 of time, but the egg-laying period is a long one, how long I do 

 not know. Any one who has watched one of the females flying 

 about the alders picking out a cluster of lice in the midst of 

 which to deposit an egg or possibly two, will realize what a slow 

 process it is. The butterflies seem to understand perfectlv 

 when there are enough of their larvae to each cluster of lice and 

 do not lay eggs in clusters already tenanted, until such time as 

 there is a certainty that the big larvae will be out of the way by 

 the time the little ones hatch. 



I have never seen F. tarquinius larva leave one cluster 

 and journey along a stem to another, and think they seldom 

 leave the spot where they first hatch. If they did this I fear 

 there would be little chance of their escaping the attack of para- 

 sitic hymenoptera, which are always to be seen around the 

 snowy clusters of lice. 



The relation of insects to their food is one of the most im- 

 portant matters for an entomologist to consider, in fact every- 

 thing, both from an economic and scientific standpoint depends 

 on a thorough understanding of these. To anyone fond of 

 nature who wishes to have a great deal of pleasure without a 

 knowledge of ten thousand ever changing Latin (or Greek) 

 names, we should recommend studying the life of some one 

 common insect in its entire annual life-history, its relation to 

 the plants on which it feeds and the parasites or other enemies 

 that feed upon it. 



