Beschreibung:
<jats:title>Abstract</jats:title><jats:p>Adult emergence period, sex ratio, female calling behaviour, and the risky mating behaviour of <jats:italic>A. aphidimyza</jats:italic> in spider webs are described. We provide evidence that <jats:italic>A. aphidimyza</jats:italic> females produce a sex pheromone and attract males, and we give a description of the location and structure of the supposed pheromone producing glands of <jats:italic>A. aphidimyza</jats:italic> based on scanning and transmission electron microscopy. This is the first demonstration of occurrence of sex pheromones for a zoophagous species of Cecidomyiidae. The question is discussed why <jats:italic>A. aphidimyza</jats:italic> is using spider webs for mating.</jats:p>