1977] 
Eberhard — Behavior of Golofa porteri 
293 
gained using the old technique, employed by Joseph (1928) in his 
study of Chiasognathus grandti, of watching partially senile males 
whose movements were slowed. Male G. porteri were extraordi- 
narily pugnacious, and even attacked fingers poked at them (espe- 
cially when the finger made contact with the base of the protho- 
racic horn). When in good condition, they fought readily. 
Results 
A. Physical combat 
Howden and Campbell (1974) described one fight they saw: 
“They grappled with their elongated forelegs, as each attempted 
to place the head horn under the opponent . . . suddenly the larger 
male successfully placed his head horn under his opponent and 
flipped him off the stalk.” They were correct in attributing a lever- 
like use to the head horn, but the “grappling” with the forelegs 
turns out to be more complex and functionally interesting than 
suspected. 
In outline, a beetle attacking a non-responsive opponent typi- 
cally behaves in the following way. Before sensing the other, he 
uses his middle and hind legs to hold tightly to the stalk, leaving 
his front legs essentially inactive. Upon sensing the opponent’s 
presence (in some cases apparently at long range, in others not 
until contact was made), he lowers his head horn so it is nearly 
but not quite parallel to the stalk. At the same time he spreads his 
front legs so as to nearly or completely encircle the stalk at about 
the level of his head (Fig. la). Particularly aggressive males as- 
sume this position with such a snap that the stalk quivers, and, as 
indicated in Fig. la, sometimes abruptly raise and lower the legs 
in an apparent threat. The male then attempts to insert his head 
horn under the opponent by raising his prothorax away from the 
stalk and lowering his head still more. Easing forward and/or 
pulling his opponent toward him with his front legs, he positions 
the end of the horn far back under the opponent’s body. As he 
does so, he brings his long front legs along the opponent’s sides 
(Fig. lb). Finally he attempts to pry him loose with a double at- 
tack. The front legs are raked postero-ventrally, dislodging the 
opponent’s middle and/or hind legs which grip the stalk, and an 
instant (about 1/30 sec.) later, the head is savagely flexed dorsally 
to lift him (Fig. lc). The result of a successful attack is to break 
