shall cause these desert wastes to cover themselves with vegetation. The 

 other two have an influence on the insect fauna of Indiana which we can 

 as yet but vaguely understand. In a paper on " Some Insect Immigrants 

 in Ohio," read before the Ohio Academy of Science, and, later, published 

 in "Science," Vol. XXII., pp. 57-59, and from which notice the map 

 is extracted, we indicated the dividing line between these two currents of 

 insect migrations in the following terms : 



" There are, seemingly, two what we may term gateways through which 

 the majority of species that have come to us from the east, have made 

 entrance into the state of Ohio, and, later, spread out over the northwest. 

 The first, and apparently the most important one of these, being at the 

 extreme northeastern part, adjoining Lake Erie, and which we might 

 term the north gate, and, second, the valley of the Ohio river, from a 

 point where it begins to form the eastern boundary of the state, south- 

 ward — perhaps to Wheeling, W. Va. Now, there also appear to be two 

 great national avenues or highways which insect migrations follow; pro- 

 gressing more rapidly along either one or the other, but not equally so 

 along both, and often following only one: the more sub-tropical species, 

 whether American or introduced, taking the southern or what I would 

 call the Great Southwestern route, while the sub arctic, including, besides 

 American, such species as have come to us from England or Europe north 

 of latitude 45° north, take what I would term the Great Northwestern 

 route. The division between these two great thoroughfares will be indi- 

 cated, approximately, by a line drawn from New York City, latitude 

 40° 43' north, to St. Louis, Missouri, latitude 38° 38' north, thence to 

 Pueblo, Colorado, latitude 38° 17' north (about), the line of separation 

 trending northward, east of St. Louis, under the influence of the Gulf 

 Stream and the Great Lakes, chiefly the former. Of course it is not to be 

 understood that this line is direct, as it is doubtless more or less irregular, 

 and, from its very nature, to some extent unstable, nor is it to be sup- 

 posed to form a radical boundary, as some northern forms gradually work 

 their way south of it, and vice versa. Yet it will, I think, be found ap- 

 proximately correct." 



From the foregoing it will be clearly observed that Indiana is itself but 

 a single factor in the determination of the nature of its insect fauna, and, 

 while the extent of its area covered by a species may be largely a matter 

 of local influences, these are not by any means important factors in deter- 

 mining the exact locality where such species shall first appear within its 



