The distraction hypothesis depends on relatively cheap extrafloral nectaries

Extrafloral nectaries may have evolved because they distract insects from flowers. For this to have occurred, extrafloral nectaries must be cheaper than flowers. This requirement stands in addition to the requirement that extrafloral nectaries must reduce the rate of insect visits to flowers. In the model examined here, the cost of each extrafloral nectary divided by the cost of each flower must be less than the proportion of reproduction threatened by insect visits.