60 
Psyche 
[June-Sept. 
infested with aphids and apparently they were feeding upon 
honeydew. This was noted only during the afternoons and 
was upon a plant species different from that utilized for 
oviposition earlier in the day. 
The oviposition habits of the Eucharidse are extremely 
varied but in no instance are the eggs laid in the nest of the 
host. They may be placed in masses in overwintering buds 
of trees, in expanding leaf and flower buds, or in seed recep- 
tacles or pods, singly or in small groups in incisions in 
leaf tissue, or at random upon the surface of leaves. One 
species, Psilogaster antennatus Gahan, oviposits on the leaf 
surface only in the immediate vicinity of a freshly deposited 
thrips egg. 
The obligatory inclusion of one or more plant species, for 
oviposition purposes, in the economy of each species of 
Eucharidse serves as a very definite check upon its local 
distribution. The presence or absence of the required ovi- 
position plants directly governs distribution, and this, in 
many instances, is much more of a limiting factor than is 
host distribution or abundance. It is because of this that 
eucharid colonies are almost invariably of small size and 
widely separated. Each of the species which has been 
studied is known through definite colonies of very limited 
extent rather than of general occurrence in a locality. The 
several species found in the Botanical Gardens at Pera- 
deniya, Ceylon, which are all parasitic on Odontomaekus, 
were found to infest only the ant colonies situated immedi- 
ately beneath the trees in which the eggs are laid. This is 
believed to be due to the members of these colonies monopo- 
lizing the areas in which their nests are situated. The 
exclusion of ants from other nests prevents their coming in 
contact with planidia on the surface of the ground beneath 
the trees, and consequently these latter are not transported 
to more distant nests. 
The distribution of a eucharid parasite is thus controlled 
by a factor which may have no influence upon the host itself 
and, as a result, the latter may be entirely free from attack 
over the greater part of its range. The Eucharidse are 
therefore relatively minor influences in the natural control 
of ants. Even within the colony limits the parasitization 
is relatively low. The colony of Stilbula tenuicornis under 
