34 



THE AMERICAN MUSEUM JOURNAL 



arrive so late in the north as to perish 

 with the approach of winter. 



This body of negative opinion as re- 

 gards the regularity of seasonal move- 

 ment, seems to be especially strong 

 among European entomologists and in 

 connection with the insect life of that 

 continent. Yet, for reasons which need 

 not be elaborated here, and on account 

 of the larger number of detailed rec- 

 ords which have been made, one would 

 expect an opposite conclusion. In tlie 

 year 1898. Mr. J. W. Tutt, the Britisli 

 lepidopterist, reviewed the scientific 

 literature in an exhaustive paper and 

 concluded that, "although nothing 

 would have given us greater satisfac- 

 tion than to have discovered in our in- 

 quiries into this subject an analogy 

 between the migrations of insects and 

 tlie migrations of birds, we can find 

 none. The latter is regular, systematic, 

 })urposeful ; tlie former appears to be 

 spasmodic, irregular, uncertain, and 

 undertaken solely on account of the 

 absolute necessities of the time." Yet, 

 as the writer has tried to show in a 

 recent article.^ a review of the litera- 

 ture of dragon fly migrations through- 

 out Europe shows a constancy of direc- 

 tion, of season, and of route, for all the 

 countries where records have been made. 



An attempt in this review will 

 l)e made to show, first — the principles 

 of behavior governing autumn butterfly 

 migrations on Long Island, and second 

 — the species of butterflies which have 

 been found migrating in observations 

 carried out with these principles in mind. 



As a result of eight years of per- 

 sonal observation on the southern coast 

 of Long Island, a route of travel has 

 been definitely established for the 

 "monarclv' butterfly. The movement 

 begins about mid- August and lasts 



'Do Insects Migrate Like Birds? Harper's 

 Magazine, September, 1915. 



through September, with stragglers ap- 

 pearing even into late October. This 

 route of nearly a hundred miles is be- 

 lieved to represent only one part of the 

 coastwise highway leading from the 

 Canadian territory and extending into 

 the Southern States — an assumption 

 which seems justified by a constantly 

 growing mass of data in the writer's 

 possession. It is a question, however, 

 how many insects cross Long Island 

 Sound — whatever ma}' be the habit of 

 the l)irds. It is probable that the insect 

 migrants which follow the southern 

 Long Island coast in autumn are 

 drawn, in very large measure, from the 

 island itself. In any case, it is evident 

 that the travelers coming down from 

 the north will be so deflected sideways 

 by the east-and-west-lying ocean shore 

 as to cause a crowded movement there 

 — a contracted procession composed of 

 many insects traveling side by side in 

 company. Thus Long Beach on south- 

 ern Long Island, a sandy, barren land 

 unobscured by trees, has been chosen 

 for these observations. 



Another assisting factor has been 

 found in the discovery that the fluctua- 

 tion from day to day, and as pro- 

 nounced as it is in the case of birds, is 

 njiparently due to the same cause, a 

 change in wind direction — although the 

 temperature change, often accompany- 

 ing the shift in wind direction, doubt- 

 less acts as an important factor. Mr. 

 0. C. Trowbridge found that when the 

 wind was from the northeast the hawk 

 migration along the Connecticut and 

 Long Island shores was comparatively 

 slight, while with the wind from the 

 southern quarter, the movement became 

 still less, or ceased entirely. But when 

 the wind shifted to the north or north- 

 west, many birds were urged southeast- 

 ward into Massachusetts, Rhode Island, 

 and into eastern Connecticut, as well as 



