1986] Heere, Windsor, and Foster — Wasps and ants 325 
only if the leaves are violently shaken or if the formicaria are 
directly disturbed. The Pheidole ants were not observed on the wasp 
nests. 
Of those wasps which construct small open nests, we found ten 
Mischocyttarus species and one Polistes species in the forest under- 
story. All but two of thirty-one active colonies encountered 
occurred on the undersides of Tococa guianensis or Maieta poeppi- 
gii leaves and only when the plants were occupied by Allomerus and 
Pheidole ants, respectively (see table 1). Two of the Mischocyttarus 
wasp species, M. latissimus and M. insolitis, build multi-pediceled 
nests arranged in rows along the midrib of the leaf. The cells are 
fused in the nests of M. latissimus while the nests of M. insolitus 
consist of separate clusters of one to four brood cells with each 
cluster supported by its own pedicle (see photograph 1). The net 
result is the subdivision and separation of the broodcells which 
comprise the nests of M. insolitus. The other species of Mischocyt- 
tarus build nests more typical of the genus; a cluster containing all 
cells supported by a single pedicel. All of the Mischocyttarus. spe- 
cies are extremely timid, flying away from their nests at the slightest 
disturbance and making no attempt at brood defense. In addition, 
two colonies (one each of Polybia signata and Polybia spp.) out of 
six total colonies of socially complex, aggressively swarming Poly- 
biinae wasps were found attached to limbs of T. guianensis. 
A small number of Tococa plants supported a disproportionate 
number of wasp colonies and this was most obvious with the nests 
of Mischocyttarus insolitis. In a census of 43 T. guianensis plants 
with Allomerus ants, five plants were the host for single Mischocyt- 
tarus nests while seven plants had two or more colonies. In a survey 
of 1 16 Maieta poeppigii plants with Pheidole spp. ants, one plant 
had three nests and two plans each had one. 
Several observations and manipulations we performed indicate 
that by nesting on these myrmecacious melastomes the wasps avoid 
nest plundering by army ants. While following the raiding swarms 
of Eciton burchelli and Eciton rapax we noticed that these ants 
never ran on to either Tococa guianensis or Maieta poeppigii plants. 
The avoidance of these two plants contrasted sharply with the army 
ants’ rapid climbing and investigating most other plants in their 
path. 
