Ultrastructure of the larval eyes of the hangingfly Terrobittacus implicatus (Mecoptera: Bittacidae)

•The larval eyes exhibit the typical bauplan of the apposition compound eyes.•All retinula cells fuse into a centrally-fused, tiered funnel-shaped rhabdom.•Larval eyes may lie in the transitional stage from ommatidia to stemmata.