Technical Abstract: Antennae of males and females of the goldeneyed lacewing, Chrysopa oculata, responded to four compounds extracted from the abdominal cuticle of males: nonanal, nonanol, nonanoic acid, and 1R,2S,5S,8R-iridodial. No volatiles were detected from the abdominal cuticle of the females. Thoracic extracts of both sexes contained antennally active 1-tridecene and inactive skatole. Iridodial was the only male-specific compound that exhibited significant attraction to Co. oculata males. A weak attraction of males was also found to nepetalactol (an aphid sex pheromone component), which may be due to the 5% iridodial present in the synthetic sample as an impurity. A plant volatile, methyl salicylate, synergized attraction to iridodial, whereas 1-tridecene was antagonistic. No females were caught in the entire study. Co. oculata males possess numerous elliptical epidermal glands on the 3rd-8th abdominal sternites, which are likely the pheromone glands. Another lacewing species, Chrysoperla rufilabris, did not produce male-specific volatiles or possess the type of gland presumed to produce pheromone in Co. oculata males, but (Z)-4-tridecene was identified as a major and antennally active compound from thoracic extracts of both sexes. Thus, 1R,2S,5S,8R-iridodial is now identified as a male-produced male-aggregation pheromone for Co. oculata, the first pheromone identified for lacewings.