Mandible Musculature

What am I looking at?

This is a dorsal (from the top, looking down) view of a cross section through the head and mandibles of a green lacewing larva (a member of the Chrysopidae family). The muscles are blue (1). It doesn’t have what we would consider a mouth. Instead, its sickle-shaped mandibles (2) inject a combination of paralyzing venom and digestive enzymes into its prey and then deliver the prey’s liquified innards back into the larva’s mouth cavity. You could think of the mandibles as being a mash-up of a hypodermic needle and a drinking straw!

Biology in the background

Lacewings and antlions (the latter members of the Myrmeleontidae family – a term derived from the Greek word myrmek, meaning “ant,” and the Latin word leo, meaning “lion”) have a lot of characteristics in common. In fact, both are members of the order Neuroptera. The larvae in both families are hunters, preying on smaller insects, while the adults are delicate, ephemeral vegans – if they feed at all.

The larvae also have a similar way of feeding; their mouthparts are formed from fused maxillae (which usually look like tiny, leg-like “feelers” flanking their mandibles) and mandibles that together form a tube. The larvae use the tube to envenomate their prey and then to suck it dry. Unlike antlions, which ambush their prey, lacewing larvae are active hunters, scurrying up and down beanstalks and rose stems in search of their next meal. Their needle-like pincers can’t pierce a thick exoskeleton, so they prefer soft-bodied prey like aphids or caterpillars. Because of their voracious appetite, green lacewings are considered a viable, environmentally friendly option for pest control; their eggs and larvae are commercially available.

Adult green lacewings are lime green and have beautiful, dome-shaped, golden eyes; the name of their genus – Chrysopa – comes from the Greek words chrysos, meaning “gold,” and ophthalmos, meaning “eye.”

A green lacewing larva can be up to 1.25 centimeters long, or slightly smaller than a human thumbnail. An adult can have a wingspan of up to 4 centimeters, or roughly 1.5 times larger than a human thumbnail.

Technique

This image was created using confocal microscopy.