EN
An organ located between bases of second antennae of an adult female of Achtheres percarum was found. Its fine structure based on SEM observations is described. It consist of four semirectangular pads covered with densely packed villiform papillae. It was concluded that the newly found organ serves for producing frontal filament, a larval attachment structure, as well as bulla, an attachment organ of adult females. Other described structures include: flap-shaped processes of the labrum, cephalic sensory papillae and vestigial thoracic legs.