192 



THE USE OF GRAPE BAGS BY A PAPER-MAKING WASP.* 



By Mary E. Murtfeldt. 



As a premise to the observation liere recorded, I may say tliat for a 

 number of years tlie practice of inclosing tlie clusters of grapes in 

 paper bags, to exclude the spores of black rot, has been very generally 

 followed throughout St. Louis County, and especially in the vineyards 

 of Kirkwood and vicinity. 



Last summer a peculiar shredding and perforation of the exposed 

 sides of many of these bags attracted my attention, but was attributed 

 to the poor quality of the paper. The present season a different and 

 better quality of bags was procured for our vineyard, but early in July 

 I again noticed and was puzzled by the same appearance of wear. 



A few days after the matter was spoken of, my sister announced that 

 she believed she had discovered the author of the mischief in the Rust- 

 red Social Wasp {Polistes riibiginosus). While standing near a grape- 

 vine she had been attracted by the faint sound of the tearing of paper. 

 Supi:)osing it to be a bird, attempting to peck the fruit, she made a mo- 

 tion to drive it away and was surprised to tin<l that instead of a bird it 

 was the insect above named. In a few moments, however, it returned, 

 and alighting upon the same bag began again, with the utmost energy, 

 stripping off, with its jaws, fibers and layers of the paper. These were 

 rapidly gathered,- by the aid of the front tarsi, into a compact packet 

 and finally borne away. 



These observations were in the course of the next two weeks repeat- 

 edly verified. A critical examination of the fruit at that time, still hard 

 and green, revealed not the slightest puncture even when exposed 

 through the holes gnawed in the bags. The unavoidable conclusion, 

 therefore, was that this wasp had made the important discovery that 

 working over ready-made paper into nest-building material was easier 

 than to manufacture it de novo from wood fiber. 



It may be added that as the paper used in the construction of the 

 bags was probably made from wood pulp, the original material was the 

 same, but the insect in appropriating it reaped the benefit of the initial 

 processes of manufacture. 



I have had opportunity to examine but one nest of the species show- 

 ing this adaptiveness since the above observations were made, but in 

 this there seemed to me there were traces of the bag paper in the lighter 

 and more yellowish color in portions of the walls of many of the larval 

 cells. 



No other species of Polistes or Vespa have as yet been observed to 



*Reaa before the Section of Biology A. A. A. S., Washington. D. C, Aug. 22, 1891. 



