202 
Psyche 
[September 
Formica ulkei workers, it may be added, readily took up 
the sugar syrup and subsequently could be seen regurgitat- 
ing to other workers. The pselaphids, Batrisodes , were not 
observed to feed on the sugar solution and often walked 
through, or were caught in, the syrup without being seen 
to take any with their mouth parts. 
In view of these data, it is possible that testaceus, under 
the proper conditions, feeds on the honey in the nests of 
bumble-bees, and since its food habits are compatiable with 
this view, it may exhibit phoresy, being carried about by 
mammals from one nest of bees to another, and consequently 
being taken in their nests as well. This is not to say that 
testaceus could not exhibit carnivorous or omnivorous be- 
havior, nor that it could not live as both an ectoparasite 
and a guest, under suitable conditions. 
The occurrence of Tachyura incurva (Say) in the nests 
of ants, especially Formica exsectoides, a host ant related 
rather closely to F. ulkei, has been noted by Ulke (1890), 
and Schwarz (1890), and its general distribution under 
bark and on the floor of forests is commented upon later. 
Despite the abundance of this species, little is known of its 
behavior. 
Incurva apparently shows some periodicity in its appear- 
ance with Formica ulkei, thus some days (August 9, 1929) 
it was present in great numbers, several to a square foot of 
nest surface, running about over the surface of the mound, 
in the grass on the moist soil around the nest, and coming 
in and out of the gallery openings with the ulkei workers, 
especially the openings near the base of the dome of the 
nest. On this date it was also present in numbers within 
the nest itself, at the ground level and the intervening gal- 
leries to the most superficial ones. On other days (August 
16, 1929) it was almost absent, several being taken from 
three nests. Again, the species would appear to frequent 
some nests rather than others in common with Batrisodes 
and other myrmecocoles. Thus one nest would yield a 
number of the carabids while adjacent nests would be 
almost devoid of myrmecocoles. I have found incurva to 
be the most abundant beetle myrmecocole of ulkei at Palos, 
