ORTHOPTERA OF NOVA SCOTIA. — PIERS. 231 



Melanoplus atlanis, a species which should be closely watched 

 because of its latent destructive abilities, is liable to appear 

 in vast numbers after such seasons. The dry summers of 

 1889, 1891 and 1894, even though a fairly wet one intervened 

 in 1893, seem to have had something to do with the plague 

 of that species on Sable Island which began about 1891; 

 and the wet season of 1896 suddenly caused its dis- 

 appearance. Meteorological records show that Nature has 

 fortunately provided a counteracting influence in such 

 matters, as periods or years of great drought are soon suc- 

 ceeded by years of abnormal rainfall. For the suppression 

 of many pests we apparently owe more to the balancing 

 efforts of Nature, exerted in various ways, than to man's 

 own exertions; although it must be admitted, inversely, 

 that it is often the cause of the periodical multiplication 

 of such pests. 



Earliest and latest appearance of adults. — The following 

 provisional table of the earliest and latest dates on which 

 adults of the vaiious commoner species have happened to 

 have been noted in Nova Scotia, is inserted chiefly that it 

 may be a convenient reference list for students who have 

 data which may modify the dates here given. One of its 

 purposes, therefore, is to court correction, and another is 

 to assist the student by cautioning him beforehand when to 

 look for the appearance and disappearance of the various 

 species. No doubt considerable changes can be made in some 

 parts of the table by further investigation. Some rare forms 

 are not included, as the dates on which they have been 

 taken manifestly could not be considered as earliest or latest 

 occurrences. 



