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[June 
responses by bees that had just previously contacted ants (31.6 
± 5.6) and those that had not (24.4 ± 5.4). 
Other tests were conducted at a mountain apiary where I. pruinosus 
analis was not found. Dowels dipped ps inch into 2-heptanone were 
placed on top of the brood combs. The bees immediately responded 
with the defensive behavior pattern. Thus previous experience with 
ants was not essential for the response. 
COMPOUNDS RELEASING DEFENSIVE BEHAVIOR 
To determine if the bees were responding to the odors of the 
ants, we tested several alarm and defensive secretions of ants by 
the same method. The bees responded with defensive behavior to 
the following compounds: 
Compound Ant Reference 
Benzaldehyde Veromessor pergandei 
(Mayr) Blum et al., 1969 
2-heptanone 
Citral 
Formic acid 
lridomyrmex pruinosus 
(Roger) 
Acanthomyops claviger 
(Roger) 
Formica spp. 
Blum et al., 1963 
Regnier and Wilson, 1968 
Wheeler, 1910 
Other odorous compounds not known to be present in any ant 
(Blum, 1969) were selected and tested in the same manner, and all 
tested were found to release a positive response. These compounds 
were as follows: 
Acetic acid 2-6 Dimethyl -4-heptanone 
Propionic acid Propanol 
Acetic anhydride Butanol 
Propionic anhydride 
The bees also responded to both methyl and ethyl alcohols, but 
this response was reduced. Therefore, bees almost certainly respond 
to chemicals not found in ants in the same manner as they respond 
to those found in ants or to the ants themselves. 
RESPONSES TO ANTS PRODUCING HIGH-ODOR AND LOW-ODOR 
Because I. humilis can be a serious pest to bees and has a com- 
paratively low level of odor to humans and because no alarm 
pheromones have been isolated from it, we suspected that the low 
odor might be the reason it can invade bee colonies with little 
