Preying on the mantis

An ovipositor is a structure used by some animals to lays eggs. For insects it is situated at the end of the abdomen, see picture left.  The organ can be highly modified. In sawflies the ovipositor has been modified as a saw-like tool to slice open leaves into which eggs are laid. In grasshoppers and crickets the ovipositor acts as a shovel to dig holes in the ground. The eggs are then laid in the resulting chamber. The ovipositor in many hymenopterans (ants, bees and wasps) has been modified for stinging or piercing, many having associated venom glands. Parasitic wasps in particular use the ovipositor to drill into a substrate so as to be able to deposit eggs directly on the host body.

Marie on Junction Hill has been carefully watching a praying mantis egg-case (known as an ootheca, see picture right) that has been deposited on a plant outside the kitchen window, waiting for the moment in which the young mantises emerge. Recently however a Mantis Parasitic Wasp (Podagrion sp.) has been loitering about the ootheca, see photo below. The word Podagrion is derived from the Greek podagra meaning gout, referring to the wasp’s swollen hind legs (see pictured above).

Using the ovipositor as a drill the female wasp pushes it into the egg-case and deposits its eggs onto the eggs of the praying mantis. When the wasp eggs hatch they eat the mantis eggs. The holes in the side of the ootheca indicate some young wasps have already emerged.

Depending on the species an ootheca can contain up to several hundred eggs. Hopefully Marie still has a chance of photographing some of the baby mantises hatching.