114 
Psyche 
[June 
similar larva has been frequently taken by the senior 
author in the twigs of T. americana in Panama. 
17. Cassidid, sp. This beetle was brilliant green in life. 
It was common on Triplaris foliage in May. Other speci- 
mens were collected in March and November. When the 
beetles were taken no ants were visible on any of the trees, 
but this may have been because the latter were too young 
to have been colonized, or more probably because the 
colonies produced in the internodes by the recently fecun- 
dated females were still undeveloped. 
18. Coccids undetermined. Although these may have 
been present in the ant-inhabited trees, they were taken 
only in the cavities which had not been colonized. 
II. Cecropia and its Inhabitants. 
Cecropias, called locally “guarumo,” are common trees 
in second-growth land and similar situations from sea-level 
up to at least 4500 feet. They are absent in the very arid 
regions, however. As has been noticed by other observers, 
they are among the first trees to come in when cultivated 
land is abandoned. Although the ants (Azteca alfari 
Emery) which inhabit the Cecropia bite severely, the tree 
is so conspicuous and easily avoided that it does not cause 
much trouble. The ants seem to get all the necessities of 
life from their trees. At any rate a well-colonized tree 
which was isolated by machete work and tanglefoot on De- 
cember 15 seemed to have its population unreduced at least 
up to February 27. The peculiar structure of the plant 
has been so often described that it need not be considered 
in this place. The following insects were found associated 
with the Cecropias: 
19. Azteca alfari Emery. Practically all the plants, 
except the very young ones, are inhabited by this ant. 
20. Azteca xanthochroa Roger, subsp. salti Wheeler, 
subsp. nov. The worker minor measures 2.5 mm. and is 
