12 Psyche [February 
EXPLANATION OF PuaTE 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. erga 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. Guaser and A. M. Witcox. 
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 (Melanoplus atlanis and M. bivittatus). The two species, 
especially M. atlanis, are extremely bad pests in this region of the 
country, attacking corn, wheat, 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 Mermithide. 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 would 
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 codperation: 
with the U. S. Bureau of Entomology. Bussey Institution, No. 146. 
