762 FIFTH REPORT OF THE ENTOMOLOGICAL COMMISSION. 



86. The pine pieris. 

 Pieris menapia Felder. 



The following account of this destructive Insect is copied from Mr. 

 Stretch's article, contributed to Papilio (ii, 103-110). 



While iu company with Professor Hagen and Mr. Samuel Henshaw, of the North 

 Transcontinental Survey, during the present summer, it was my fortune to find this 

 delicate butterfly in excessive profusion, and as it must now take rank among our 

 injurious insects, it is thought that the following notes may be worthy of publication. 



Distribution. — The species was first seen by our party at Spokane J'alls, in Wash- 

 ington Territory, near the Idaho line, ou July 22, the altitude above the sea being 

 about 1,900 feet. The few specimens captured were all males and much worn. A 

 number of others were seen, but their peculiar habit of flitting around the tops of the 

 larger trees prevented capture. On July 23 I found the larvae and pupae in great 

 numbers on the trunk of a yellow pine, at a point on the Colville road, about ten 

 miles north of the crossing of the Little Spokane River, and about ten miles south of 

 Loon Lake, but did not notice the insect on the wing. At Loon Lake a few worn 

 specimens were seen (all males), and I again found the larvae and pupte on the trunks 

 of pine trees in immense numbers, say not less than from 200 to 300 within six feet 

 of the ground. Between Loon Lake and Brown's, the latter place being fifty-four 

 miles from Spokane Falls, the same phenomena were again noticed, but with the 

 dift'erence that the imago was emerging in great numbers. I took probably seventy 

 specimens, both male and female, in a few minutes, and over one hundred and fifty 

 in the course of the day. It would easily have been possible to make the number 1,500. 

 Most of those taken were picked ofi^ the trunks of the trees, just fresh from the pupa, 

 having never been on the wing. At Brown's both larvae, pupaj, and imago wore 

 equally common, though not many of the latter were on the wing until towards eve- 

 ning, as the day was cloudy. Towards evening the sun shone out for a few minutes, 

 and instatitly 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 gath- 

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

 though not more than two feet high, ou each terminal bunch of needles, from one to 

 twelve larvae or pupae could be counted, and every weed could show its quota ot 

 pupae. Our trip did not extend northward beyond this point, but the appearance of 

 the forest showed that we had not reached the limit of the plague. On July 25 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 bal- 

 samii) and tamarack {Pinus contorta), 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 {Pinus ponderosa) and the predominance of fir and tamarack 

 along the line of travel. On July 27 we saw a few sporadic butterflies as we ap- 

 proached Spokane Falls, say five miles from town. Round the latter place it did 

 not seem to be abundant, but occurred ou 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 atfected area may be it is impossible 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 iu the south ; and consequently the same 

 phenomena which we are here called to note may occur in localities where the tim- 



