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Psyche 
[Vol. 93 
the organized raids of army ants (Ecitonini). Below we describe 
numerous species of vespid wasps which form nesting associations 
with Allomerus octoarticulatus ants inhabiting the plant Tococa 
guianensis Aublet (Melastomataceae) and with Pheidole spp. ants 
inhabiting Maieta poeppigii Mart, ex Triana (Melastomataceae) 
and show that by nesting on these plants the wasps escape army ant 
raids. 
Study Area 
The study site is in Loreto, Peru, at Estacion Biologica Callicebus 
which is located 3-5 km. south of the village of Mishana on the Rio 
Nanay in Loreto, Peru. The village is approximately 30 km. east of 
the confluence of the Nanay with the Amazon River near Iquitos. 
The Estacion consists of a forest camp and an extensive trail net- 
work through the apparently uncut and non-indundated forest. The 
forest grows on low hills composed of a mosaic of white sand and 
dark brown sand and is drained by tea-colored streams. These sedi- 
ments are derived from the ancient Guiana and Brazilian Shields 
and have been eroded and redeposited following the Andean uplift. 
White sand areas, though common in the Rio Negro drainage, are 
infrequent in the Western Amazon (see Kinsey & Gentry, 1979). The 
brown sand soils support a flora typical of much of the non- 
indundated Peruvian Amazon. The white sand soils have a distinc- 
tive flora which shows strong affinities to the flora of the Guiana 
Highlands. The latter areas also have a shorter forest canopy (20 m. 
vs. 30-35 m.); fewer lianas, straighter, thinner, and less-branched 
understory trees and shrubs; and a thick mat of roots over the white 
sand. The observations presented below were collected during 8 
short visits (4 by EAH in August 1978, October 1978, in December 
1979, and in June 1983; 1 by DMW in November 1978; and 3 by 
RBF in August 1974, 1978, and 1980). 
Observations and Results 
Understory ant-plants are common at Mishana, especially on the 
brown sand soils, and are represented by a diversity of families: 
(Melastomataceae) Tococa (3 spp.), Maieta (2 spp.); (Chrysobala- 
naceae) Hirtella (2 spp.); (Boraginaceae) Cordia nodosa ; (Rubia- 
ceae) Duroia hirsuta. Of these, only Tococa guianensis is abundant 
on the white sand areas. This 2-4 m. treelet is most common on 
