1970] 
Spangler and Taber — Honey Bees 
187 
resistance. The previous tests had already shown that the bees 
readily responded to /. pruinosus analis and to 2-heptanone, an alarm 
pheromone of I. pruinosus. 
1 . humilis workers were obtained and placed on the wooden top 
bars of several brood combs. The responses of the bees to these 
ants were reduced both in frequency and vigor from the responses 
to I. pruinosus analis; the ants generally moved freely about beneath 
the bees. Occasionally a bee would detect one of these ants, usually 
by contacting it with its antenna. The bee then went through the 
described behavioral response, turning its body, fanning its wings, 
and kicking with the rear legs. Comparatively few of the bees which 
detected I. humilis turned a full 180 degrees. When I. humilis 
workers were crushed on wooden dowels which were also laid on 
the tops of brood frames, some response was noted, but again it was 
sharply reduced. 
DISCUSSION 
Honey bee workers responded readily to several compounds that 
are not associated with ants and to several that are. This defensive 
behavior pattern enables the bees to rid their colony of harmful 
pests so the response appears to be a defense mechanism against 
ants. It is unlikely that the compounds tested which are not associ- 
ated with ants would enter a colony under normal conditions, and 
strong foreign odors in a hive would frequently, if not usually, 
result from the presence of ants. 
Bees are successful in keeping practically all small odoriferous 
Dolichoderine, Formicine and Myrmicine ants out of their colonies. 
The fact that honey bees are apparently less able to detect and 
respond to ants which have little demonstrable odor indicates that 
the odors of the ants play a key role in their detection. Therefore, 
Argentine ants, /. humilis , which are probably nearly odorless to 
honey bees, have been able to invade and damage bee colonies and 
often cause colonies to abscond. Were the bees able to detect these 
ants as readily as they detect others, they would doubtless rid their 
colonies of them. 
Boch et al. (1970) described the behavior of honey bees exposed 
to 2-heptanone at the hive entrance as “short jerks forward and in 
reverse.” Thus, 2-heptanone can apparently release more than one 
type of response. They also reported evidence to support previous 
suggestions that the primary alarm pheromones of the honey bee are 
associated with the sting and that 2-heptanone may be more impor- 
