196 
Psyche 
[September 
shrews, rats and small mammals in general, especially the 
rodents and insectivores (LeConte, after Brendel, 1866; 
Riley, 1889; Schwarz, 1890; Dury, 1892; Kellogg, 1914, 
and Jeannel, 1922) ; in the nests of birds (Imms, 1924) ; 
in the nests of Hymenoptera, viz. Vespidae, Bombus, and 
Formica (Jeannel, l.c., and Imms, l.c.). Imms (l.c.) has 
even mentioned its occurrence in rotton wood, and it was 
taken under “chalk flints” by Hardy (1848). 
The exact relation of this species to its several hosts is 
not definitely known. Its status has been variously placed 
as that of an ectoparasite feeding upon the hair or secre- 
tions of small host mammals ; as that of a scavanger, living 
on the nest refuse ; as a tolerated guest ; or as one of those 
species exhibiting phoresy, and the literature is partially 
covered and the questions involved discussed by Kellogg, 
1914, Riischkamp, 1914, and Jeannel, 1922. Dury and 
Rlatchley believe this leptinid to be a guest, possibly even 
feeding upon mites and fleas associated with testaceus in 
mammal nests. The presence of the species in decaying 
wood may indicate ability to live a more active life, or may 
be an accidental occurrence. On the other hand, testaceus 
may exhibit phoresy. This uncommon phenomenon has 
been discussed by a number of investigators, among which 
may be mentioned the account of Lesne in 1896, Riischkamp, 
l.c., Banks, 1911, and Wheeler, 1919. 
If testaceus exhibits phoresy, the species may live in the 
nests of bees, feeding upon honey and pollen, and using 
small mammals, such as field-mice, for transportation from 
one nest of bees to another. Testaceus is well-known as an 
inhabitant of the nests of bumble-bees, e.g., the work of 
Gorham in 1869; and Wheeler, 1923, p. 113, says of these 
bees that their colonies are an annual occurrence. The 
fecundated queen overwinters and in the spring chooses a 
small cavity in the ground or in a log, preferably the aban- 
doned nest of a mouse, to line with grass or other materials 
at hand and so start the incipient colony. It is an interesting 
possibility that testaceus may live as a guest in the nests of 
Hymenoptera, and exhibit phoresy as the occasion arises. 
It is even possible that this phoresy, if it exists, is a stage 
in parasitism and the blind condition of the beetles would 
