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 
decemlincata) 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 (Slissus 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: (1) 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 /phiclides ajax occa- 
sionally reaches Massachusetts as a visitor and a visitor only; 
Lertias philenor, however, finds a limited amount of food in 
