12 Psyche [February 



Explanation of Plate I. 



In all figures only a portion of the terga (which are symmetrical) 

 has been shown, since the missing portions are exactly like those 

 figured. 



Fig. 1. Terga and wing bases of a Plecopteron. 

 Fig. 2. Terga and wing bases of the Coleopteron Photuris. 

 Fig. 3. Terga and wing bases of Embia major. 

 Fig. 4. Terga and wing bases of the Dermapteron Echinosoma.^ 



ON THE OCCURRENCE OF A MERMIS EPIDEMIC 

 AMONGST GRASSHOPPERS.! 



By R. W. Glaser and A. M. Wilcox. 



While engaged in some investigations on grasshoppers, near 

 Dummerston Station, southern Vermont, this past summer (1917), 

 our attention was attracted to a high mortality amongst these 

 insects (Alelanoplus atlanis and M. hivitiatus). The two species, 

 especially M. atlanis, are extremely bad pests in this region of the 

 country, attacking corn, w^heat, oats and clover to such an extent 

 that during certain summers the farmers become nearly frantic. 

 Therefore, the high mortality amongst the grasshoppers, which 

 appeared during the latter part of August and the early part of 

 September, was exceedingly gratifying. 



We soon discovered that this mortality was due to a species of 

 Nematode belonging, as we supposed at the time, probably to the 

 family Mermithidse. Subsequently (Sept. 20, 25 and Oct. 6), we 

 sent large shipments of these worms to Dr. N. A. Cobb, of Wash- 

 ington, D. C, for identification. Dr. Cobb was able to give us 

 only a provisional identification on account of the utter absence of 

 males in all of our shipments. We made collections of parasitized 

 grasshoppers from a large variety of fields and as stated, sent a 

 large number of specimens, but curiously enough no males were 

 found. Dr. Cobb in a letter said: "Nothing I have learned w^ould 

 preclude your specimens from belonging to the same species as that 

 referred to by Leidy under the name of Mermis ferruginea, which 



1 Contribution from the Entomological Laboratory of the Bussey Institution in cooperation: 

 with the U. S. Bureau of Entomology. Bussey Institution, No. 146. 



