132 LEPIDOPTERA. 



it is everywhere pretty common, extending to the Hebrides, 

 Orkneys, and Shetland Isles; and is abundant all over 

 Ireland. 



Abroad its range is extensive, all Northern Europe ; 

 Central Europe, especially in the Alpine regions ; Eastern 

 Siberia ; Northern Asia, Labrador, and (Greenland. In some 

 of these countries it is noted for the destructiveness of its 

 larvaB on grass land. Kollar says, "In the years 1810 and 

 1817 entire hills in the Hartz territory which were covered 

 in the evening with the finest green were found bare the 

 next morning, and the ruts in the roads leading to them 

 filled with caterpillars, and sometimes the roads themselves 

 partially covered with them so that they became slippery 

 and filthy through the caterpillars being crushed." Another 

 writer says, " On the 1 1th of June last the foresters 

 informed me that in a certain district of the Obergehren 

 Forest, caterpillars of which they sent some examples in 

 spirit, had made great havoc in the pastures, and were so 

 abundant that as one walked over the infested ground they 

 crackled under foot. I was unable to visit the place in the 

 Eennsteig, at about 2000 feet elevation, until the 28th of 

 June. The locality most infected was a wood-clearing of 

 about ninety acres ; all the pasture had become entirely 

 withered in consequence of the roots of the grass having 

 been eaten by the caterpillars. At this time the greater 

 part of the larv{« had become pupae. In a square foot I 

 counted from twenty-five to thirty larvfe and pup^e, which gave 

 for the ninety square acres 69,084,000 individuals." There 

 are similar records in our own country. The local papers 

 described, in 1881, a visitation in North Lancashire and York- 

 shire : "Great commotion prevails in Clitheroe and the 

 district surrounding Pendle Hill in consequence of the 

 arrival of a large quantity of caterpillars which occupy the 

 land from Wisley to Mearley, near Pendle Hill, a distance 

 of about three miles. The}' travel together in thousands at 

 a good speed and devastate the land over which they pass to 



