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[Vol. 92 
probably larvae actively fed on the fungus mycelium infesting the 
food particles. Normally, within 24 hours fungus would invade the 
food substrate. This was a serious problem in most cultures of 
aleocharines since fungus mycelium would quickly spread through- 
out the petri dish, commonly entangling the adults or otherwise 
restricting their activities. This problem did not become serious in 
colonies of M. venustula. In these cultures the food became covered 
by uniform velvety pile of fine short fungus fibers, but these did not 
develop into the large fibers of fungus mycelium common in other 
cultures. Adult M. venustula were often observed grazing in 
numbers on fibers of the pilose fungus growth on food particles. 
These observations suggest that growth of the fungus was restricted 
by continual grazing of the beetles. This hypothesis is further sup- 
ported by the fact that as adults of the colony began to age, toward 
the middle of June, and become less vigorous and many had died 
(Figure 1), fungus on the food began to form a more normal mass of 
long mycelial fibers. This was first noticed on June 11, after egg 
laying had ceased. 
Comparable observations for larvae are not available. Larvae 
were kept in individual dishes and could not have the same effect on 
fungus growth as could the more numerous adults. However, fungus 
mycelium and spores, along with bits of food substrate, were found 
in the guts of many slide mounted larvae. It is not possible to 
eliminate the possibility that the fungus was ingested accidently 
while feeding on the more normal food. However, this seems 
unlikely in view of the large amount of fungus in the guts of many 
larvae. 
Mating was commonly observed in the petri dishes and was typi- 
cal of that described for other aleocharine staphylinids (Peschke 
1976, Ashe 1981). The relatively low proportion of males collected 
and included in the cultures (Figure 1) appears to reflect a natural 
unequal sex ratio present in early spring when collections were 
made. 
A behavior which may be associated with mating activity but 
which appeared to be of much more general occurrence was regu- 
larly observed in cultures of M. venustula. If one individual crawled 
across or touched another, it often initiated a short, very rapid 
chase, with the mouthparts of the following beetle at the apex of the 
abdomen of the leader. This chase would continue for distances of 
