Oviposition behaviour of Tetrathemis polleni (Selys): a possible adaptation to life in turbid pools (Anisoptera: Libellulidae)

A settled female of T. polleni places a mass of eggs, up to 2 m above the prevailing water level, on the surface of upright sticks or dead sedge stems. The eggs, several hundred to a mass, adhere to the stem and hatch there, without falling into the water. Females of exophytic Odonata seldom attach eggs directly to a substrate, and very rarely when settled. Such behaviour may enable T. polleni to oviposit successfully in turbid, astatic, standing waters immediately after the onset of the rains and thus to prey intensively on larvae of the mosquito. Anopheles gambiae Giles. In its oviposition behaviour, the African T. polleni closely resembles other species of Tetrathemis in Africa and India, except that it selects dry bark or dead stems instead of green foliage as oviposition substrates.