LS at 
5 
Insect Collecting in Zero Weather in Illinois. 
BY O. H. SWEZEY. 
(Presented at meeting of Mareh 3, 1921.) 
The week before Christmas, December, 1920, I spent at a 
farm house near Rockford, Ill. It was hardly a favorable 
time for collecting insects, as for a part of the time the tem- 
perature dropped as low as zero. However, a few interesting 
captures were made, which are now exhibited. 
In a cavity in the center of a block of wood, recently 
brought in from the forest, was found a colony of the large 
black wood ant, Camponotus pennsylvanicus (Deg.), of which 
a series of specimens was secured. Among these ants some 
queer brown insects were noticed, and sixteen of them were 
collected. These proved to be a species of Staphylinid beetle, 
Xenodusa cava (Lec.), which is an inquiline in ants’ nests. I 
had never before seen any of these insects. The ants feed the 
beetles and their larvae, and they in turn lick the clusters of 
hairs on the sides of some of the adbominal segments of the 
beetles. An account of this is given in Wheeler’s Ant Book. 
In another cavity, which was an old channel of some wood 
borer, opening out to the exterior, was a mud nest of some 
wasp, containing several cells in a mass. From this mud nest, 
four pretty, white-marked Ichneumonids * issued the latter part 
of February; also 143 small Tetrastichus issued during the 
middle of the same month. The latter were determined as 
TVetrastichus johnsoni Ashmead, by Mr. Timberlake.‘ One 
wasp, Ceropales fraterna Smith, issued March 3. From what 
has been previously observed of this wasp, it may have been 
a parasite on the wasp which was the builder of the nest. If 
so, the true builder of the nest was not learned, for the total 
emergences are given above. On examination of the eight cells 
of the nest, one cell contained the cocoon of the Ceropales fra- 
terna; four cells contained the cocoons of the Ichneumonids ; 
two cells contained cocoons of the Ichneumonid from which 
Proce. Haw. Ent. Soc., V, No. 1, October, 1922. 

* Mesostenus discoidalis Cresson, as determined later by R. A. Cushman. 
+ Identification confirmed by Mr. A. B. Gahan by comparison with 
types in the U. 8. National Museum. 
