334 The Botanical Gazette. [December, 



A new herbarium pest. 



C. V. RILEY. 



In the year 1890 a number of small Geometric! larvse, re- 

 calling somewhat in appearance those of the genus Aplodes, 

 were found by the botanists of the Department of Agriculture 

 infesting certain dried plants in the Department herbarium, 

 and especially those which had been received from Mexico 

 and Lower California, from Dr. Edward Palmer. Dr. J. N. 

 Rose first observed it in January, 1890, on plants from La 

 Paz, but it was still more abundant in a collection from the 

 State of Colonna, Mexico, made in the beginning of the 

 present year. Being referred to me for identification, I be- 

 came much interested in the matter, as it was the first case 

 that had come under my notice of a Geometrid larva feeding 

 upon dried plants. The matter acquired additional interest 

 also because the species was evidently new and there was 

 danger of its being spread through distribution into other 

 parts of the world. I therefore took steps to watch the course 

 of the insect and rear it to the imago state. This was done 

 some time ago and I have had drawings of the different stages 

 finished for some time, and call attention to the matter now 

 because the trouble has grown in the Department herbarium 

 and it is of sufficient importance to put on record. The first 

 moth emerged October 22d, 1890, and others were subse- 

 quently reared from material received from time to time from 

 the Department herbarium. While the larva was first dis- 

 covered, as stated, on Mexican plants, it has not confined its 

 work to such plants, but has spread to others and is by far the 

 most destructive herbarium pest which the botanists in charge 

 have to deal with. . Plants of the genus Coulterella, for ex- 

 ample, which were sent by Dr. Rose to Dr. C. Hoffman in 

 Berlin, have been so injured that but one perfect flower re- 

 mained; yet, according to the observations of Mr. L. H. 

 Dewey, in overhauling the herbarium, the insect's work is 

 still mostly confined to southwestern plants; after these from 

 ' exico chiefly those from California. In some cases eastern 

 plants have not been attacked, even when associated with 

 western, but in one case at least, viz. : Rhus toxicodendron, 

 eastern plants have been extensively infected. 



1 he larva feed on the flowers and also to some extent on 

 the leaves M ore rare l y they feed on the hard fruits an d 



seeds. I he following list, kindly prepared by Mr. Dewey, 



