Light micrograph with darkfield illumination of a nymph of the common backswimmer (Notonecta glauca). Backswimmers are aquatic insects in the family Notonectidae. Insects in this family are commonly referred to as backswimmers or greater water boatmen. Notonectids propel themselves through the water with their ventral side (belly) facing upwards, hence their common name of backswimmers. The nymphs have a shorter abdomen compared to adults and the red complex eyes (left) are much smaller compared to adult insects. Magnification: x50 when printed at 10 centimetres wide.