insect laying eggs using her ovipositor ichneumon wasp ovipositing eggs inside caterpillar

In males, the reproductive structures are often located on the ninth abdominal segment and may include an aedeagus (penis) or pair of claspers. In females, the reproductive structures are located on the eighth and ninth abdominal segments and usually take the form of an ovipositor. The ovipositor is comprised of paired appendages (usually three) which form into a shaft that is used for laying eggs.  Eggs may be deposited in various locations including into or on plant tissue (photo 1), in the ground or even into the bodies of animals. For example, some species of Ichneumon wasps (Order Hymenoptera, Family Ichneumonidae) use their ovipositor to pierce the bodies of caterpillars and lay their eggs within (photo 2). Depending on the Ichneumon species, venom may also be injected into the host's body along with the eggs in order to prevent the host's immune system from destroying the eggs. When hatched, the larvae feed on the body tissues of the caterpillar, essentially consuming it from the inside, out.

Photo of Ichneumon wasp courtesy of Tim Haye, Universität Kiel. Image 1445011. www.insectimages.org.