382 ENTOMOLOGY 



poplars, and common in Europe, Siberia and Japan, was found 

 in New Jersey in 1882 and in New York in 1896, though 

 known for many years previously in Massachusetts. It be- 

 came noticeable in Ohio in 1901, and is steadily extending its 

 ravages, being reported recently from Minnesota. 



From Colorado the well-known potato beetle (Leptinotarsa 

 decemlineata) has worked eastward since 1840, reaching the 

 Atlantic coast within twenty years, and has even made its way 

 several times into Great Britain, only to be stamped out with 

 commendable energy. The box-elder bug (Leptocoris trivit- 

 tatus) is similarly working eastward, having now reached 

 Indiana. The Rocky Mountain locust periodically migrates 

 eastward, but meets a check in the moist valley of the Missis- 

 sippi, as has been said. 



The chinch bug (Blissus leucopterus) , the distribution of 

 which has been traced by Webster, has spread from Central 

 America and Mexico northward along the Gulf coast into the 

 United States, following three paths : ( i ) Along the Atlantic 

 coast to Cape Breton; (2) along the Mississippi valley and 

 northward into Manitoba; (3) along the western coast of Cen- 

 tral America and Mexico into California and other Western 

 states. Everywhere this insect has found wild grasses upon 

 which to feed, but has readily forsaken these for cultivated 

 grasses upon occasion. The harlequin cabbage bug (Murgan- 

 tia histrionica) has spread from Central America into Califor- 

 nia and Nevada, and has steadily progressed in the Mississippi 

 basin as far north as Illinois, Indiana and Ohio, though it 

 appears to be unable to maintain itself in the northern parts 

 of these states. This insect required about twenty-five years 

 to pass from Louisiana (1864) to Ohio, spreading through its 

 own efforts and not commercially to any great extent. 



Every year some of the southern butterflies reach the North- 

 ern states, where they die without finding a food plant, or else 

 maintain a precarious existence. Thus 1 p hie tides ajax occa- 

 sionally reaches Massachusetts as a visitor and a visitor only ; 

 Lcertias philenor, however, finds a limited amount of food in 



