278 



On May 26 of the present year our attention was called to the 

 swarms of these mites crawling on windows and over carpets and fur- 

 niture in rooms, some of which were not accessible to sunshine, and had 

 not been kept warm during winter. On June 7, we found the same 

 species exceedingly abundant on the leaves of Timothy on the lawns in 

 the vicinity of the infested dwellings. Those which we had observed 

 indoors were seemingly fully developed, whereas those on the grass 

 were of all sizes, the minute individuals predominating, and usually 

 forming companies or families grouped about mature individuals. A 

 month later however, therB were comparatively few remaining on 

 the grass, and they had long since disappeared from the dwellings. 

 On July 29, I could find but a single individual after long search, this 

 one being, as I suppose, full grown. From this date up to September 

 26, when they were again observed on Timothy, nothing could be found 

 of them on the grasses or indoors. Wherever these mites occurred on 

 the grass the latter soon began to have a scalded appearance. In fact, 

 the prevailing opinion seems to be that the species of Bryobia, found in 

 this country, are of vegetal food habits. This, if true, would indicate 

 that they entered our dwellings for the purpose of hibernating; an idea 

 which is somewhat strengthened by the fact that in some of the houses 

 which they frequented there were no growing x^lants. Besides this, a 

 species similar to the one observed by me was sent to Prof. A. J. 

 Cook, from Scotts, Mich., by Mr. Adam Haas, on December 12, with 

 the complaint that the window curtains and carpet on the soutli side 

 of his parlor were full of them.* But, if their object were simply to 

 secure protection from the cold weather, why should they stay so late 

 in the spring ? 



This occurrence of mites in dwellings is not confined to Indiana and 

 Michigan. In the Country Gentleman of June 9, 1881, a correspondent 

 of Susquehanna County, Pa., complains of their occurring on kitchen 

 windows and in a box of clothing in a seldom used chamber, the 

 walls, floor, and furniture of the latter, in the corner near the box, being 

 almost covered with the mites. In his reply Dr. Liutner states that 

 the mites were allied to the red spider. In a private letter of July 9? 

 1881, Dr. Lintuer writes me that under date of June 16 a correspondent 

 complains of the occurrence, in great numbers, of mites in a newly 

 lathed, plastered, and painted house. 



In Europe the massing together of a similar species, Petrohia lai)idiun^ 

 during autumn, has been repeatedly observed. Duges found whole 

 families under stones in public walks in the south of France, he having 

 in summer observ^ed it in families on the under side of leaves of the 

 Plane-tree.f What was supposed to be the same species has been sev- 

 eral times reported as swarming under pebbles and gravel in England. 



*Michigaa Farmer, January 9, 1886. 



t Economic Entomology. Aptera. By Andrew Murray, pp. 119, 120. 



