I04 



stantly the air was alive with butterflies, flitting round the pines 

 in countless numbers, and glistening against the dark green of 

 the young timber, like the most delicate snow-flakes. Some idea 

 of the immense numbers of the insect may be gathered from the 

 fact that in the infected district near Brown's, on every little pine, 

 though not more than two feet high, on each terminal bunch of 

 needles, from one to twelve larvae or pupae could be counted, and 

 every weed could show its quota of pupae. Our trip did not ex- 

 tend northward beyond this point, but the appearance of the 

 forest showed that we had not reached the limit of the plague. 

 On July 25th we returned to Loon Lake, finding the insect in 

 all stages, from full grown larva to imago, excessively abundant, 

 with eggs, larvae and pupae on both the fir {Abies balsamii) and 

 tamarack {Piiiiis contortd) as well as on the pines. Returning 

 south, the insect was common for eight miles ; in the next three 

 it grew gradually rarer, and then we lost it altogether, though this 

 may be partly the result of the greater rarity of yellow pine 

 timber {Piniis ponderosd) and the predominance of fir and tama- 

 rack along the line of travel. On July 27th we saw a few spora- 

 dic butterflies as we approached Spokane Falls, say five miles 

 from town. Round the latter place it did not seem to be abund- 

 ant, but occurred on the 28th in greater numbers, as we ap- 

 proached Cheney by rail, and was seen about ten miles west of 

 that place, or about twenty-five miles southwest of Spokane 

 Falls, near the edge of the timber. 



What the extension of this affected area may be it is impos- 

 sible to say, as there are no accessible data at hand ; but as the 

 insect is found in California, in Plumas county about Lake 

 Tahoe and elsewhere, more than 630 miles to the southward, and 

 also in Colorado and Vancouver's Island, it is evidently of very 

 wide distribution, latitude in the north taking the place of altitude 

 in the south ; and consequently the same phenomena which we are 

 here called to note may occur in localities where the timber is 

 both denser and more valuable than in that under consideration. 

 Whether it occurs in the coast range in Washington Territory I 

 do not yet know, although we might expect its presence, as the 

 Cascades offer a similar vegetation, as well as from the general 

 similarity of the Rhopalocerous fauna on both sides of the great 

 Columbia plateau, as evidenced by the occurrence of the same 

 species of Pieris, Colias,Argynnis, Satyrus and Papilio. The area 

 actually visited where serious damage has been already commit- 

 ted extends about 25 miles north and south, with an unknown 

 width, and in this region ^^//the yellow pines have been nearly or 

 totally stripped of their foliage, as well as many of the smaller 

 species of ConifercB. 



The appearance of the Forest is peculiar. The first impression 

 was that fire had scorched the tops of the trees, so brown and 

 withered did they look in their clothing ot dark, blackish moss ; 



