
952 THE AMERICAN NATURALIST. 
readily distinguished by their coloration, which is never ashy or 
silvery gray. At first sight F. subsericea resembles cinerea, but 
the former never has hairs on the lower surface of the head. 
This character definitely separates the two forms, notwith- 
standing the fact that subsericea presents color variations in the 
direction of czzerea.! 
The cinerea nests were not seen til it was too late in 
the year to secure the winged sexes, which, like the males and 
females of our other species of Formica, probably make their 
appearance during June and July. Even the dealated mother 
queens were found in but one of the smaller nests. All the 
nests, however, were full of worker larvae and pupa. The 
latter were generally enclosed in cocoons, but quite a number 
of nude pupz were also seen in many of the nests. In this 
respect cinerea resembles the Formicidz of the pallide-fulva, 
fusca, and subpolita groups, the worker larvae of all of which, 
in contradistinction to F. rufa and its varieties, have a very 
pronounced tendency to omit spinning a cocoon just before 
pupation. At Rockford during the past summer many of the 
nests of these species contained only nude pupa. This may 
have been due to the great amount of moisture in the nests, as 
June and July were unusually rainy. At any rate, I observed 
that the cocoons were relatively much more abundant during 
the dry weather late in August. 
In its habits F. cinerea is very similar to the ants of the 
fusca group. It was seen in great numbers visiting the flowers 
in the meadow and attending great droves of Aphide on 
the willows along the stream. The walls of the galleries 
in some of the formicaries were tenanted by teeming colonies 
of the minute lestobiotic, or thief ant, Solenopsis molesta Say. 
In one cinerea nest I took a myrmecophilous histerid beetle 
(Heterius brunneipennis Randall). 
ROCKFORD, ILL, September 1, 1902. 
1 At Rockford I discovered two rather large nests of a form which should, per- 
haps, rank as a distinct variety of Z. fusca allied to subsericea. The ants from 
these nests are smaller and more graceful in stature than the common subsericea, 
the legs and antennz are red like those of cinerea, and the body is so thickly 
overlaid with silvery white, appressed pubescence that the black ground color 
is hardly visible. This form may be called Formica fusca var. argentata var. nov. 
