144 
Psyche 
[March 
high probability of contacting each other. Even if the females were 
not related, it could be adaptive to merge aggregations to increase 
the effectiveness of the startle response since 2 females dispersing 
together or slightly out of phase may provide more time for 
nymphal dispersal. Even if 1 female is captured, the remaining 
female can facilitate reaggregation and maintenance of the aggrega- 
tion. The interaction of 2 or more females may also facilitate normal 
maintenance of nymphal aggregations, promoting increased feeding 
efficiency and maturation. 
Adult G. compressa maintain stable aggregates as do U. crassi- 
cornis and P. vittata. In both of the Hoplophorionini species, 
aggregations are stable for 15 to 20 or more days. During this 
period, individuals within the aggregation become progressively 
more sensitive to disturbances. Individual teneral adult U. crassi- 
cornis are unpalatable to Anolis lizards, but in addition, employ 
both an individual and collective cataleptic behavior to reduce 
predation (Wood 1975, 1977b). Older aggregations disperse explo- 
sively about the time of sexual maturity, but do not appear to 
reaggregate. The explosive dispersal and subsequent reaggregation 
of adult G. compressa is an extension of nymphal behavior and 
appears to be an effective response to predators such as anoles 
which are often seen walking or sunning themselves on branches 
similar to those where treehoppers are found. 
Acknowledgments 
My thanks to Dr. Glenn Morris and Frank Hale for their help 
with the field work, and Dr. Gary Hartshorn for the host plant 
identifications. The faithful and useful criticisms by Dr. David Horn 
on the manuscript were, as usual, very helpful. Mrs. Carole Kenney 
typed several manuscript drafts and, as usual, kept her sense of 
humor. Research funding was provided by NSF grants BNS 
74-19764 and BNS 74-19764 A01 . I thank Ms Sarah Landry for the 
excellent drawing in Figure 2. 
Literature Cited 
Bequaert, J. 
1935. Presocial behavior among the Hemiptera. Bull. Brooklyn Entomol. Soc. 
30: 177-191. 
