1974 ] 
Haskins & Haskins — Myrmecia vindex 
265 
Card Marking 
No. of Cocoons 
Substances Impregnated 
C 
7 
Caproic acid 
F 
6 
Formic acid 
M 
7 
Methyl benzylamine 
O 
5 
Oleic acid 
L 
7 
Control 
Immediately on exposure a worker on the crater seized one control 
and dragged it inside the nest. A second worker, encountering an 
oleic-acid-treated cocoon, started away. At 7 132, 1 caproic-acid- 
treated cocoon was dragged into the nest, followed at 7 :35 by a 
second control cocoon. At 7 :37 a cocoon from the formic acid group 
was taken to the nest. Between 7:37 and 7:40, 3 additional formic- 
acid-treated cocoons were taken into the nest, and one-half minute 
later the last control cocoon was taken in. One of the remaining 
two formic acid cocoons was inadvertently toppled into the nest 
by another worker, leaving 1 on the card. The other groups were 
untouched. At 8:02 p.m., when darkness forced cessation of observa- 
tion, all cocoons treated with oleic acid, methylbenzylamine, and five 
of those with caproic acid remained in place on the cards. One 
cocoon treated with caproic acid had been deposited with the oleic- 
acid-treated group. 
At 6:00 a.m. the following day, 3 of the caproic-acid-treated co- 
coons had been removed, but it was not possible to determine whether 
they had been taken into the nest or discarded. Some grains of 
earth had been scattered on the caproic-acid-treated card. 
Observations were continued throughout the day, but no further 
attention was paid to the remaining cocoons. However, when the 
cards were removed from the crater at 7 :oo a.m. on the third day, 
it was found that a new entrance-hole had been excavated under 
the card carrying the oleic-acid-treated cocoons. 
It was clear that oleic acid, caproic acid, and methylbenzylamine 
effectively inhibited return of the cocoons to the nest by the workers, 
in marked contrast to those treated with formic acid and the controls, 
which were brought in promptly. Digging behavior was observed in 
the vicinity of oleic acid. In these experiments, however, the oleic 
acid objects were not buried nor transported to kitchen middens — - 
perhaps because such middens of M. vindex are often located near 
the nest entrance. Indeed, it is an interesting behavioral characteristic 
of M. vindex , at least in this population that, at the seasons of 
maximum brood production, empty cocoons and pupal exuviae are 
frequently piled near the nest entrance. That this disposition may 
be more than accidental is suggested by the behavior of some colonies 
