Insect Mouthparts: Part Two

Last week we talked about some basic mouthparts found on insects. But this week we are going to explore some funkier specimens.

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Chewing mouthparts are not boring. Let's take this male lucanid stag beetle. The mandibles extend forward and are functionally useless for feeding. Male stag beetles battle each other by locking mandibles and 'wrestling' with each other for mating rights.

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A closer look reveals the distal end of the mandibles in the upper left quadrant of the image. The mandibles end in spikey teeth.  The upper right shows a ventral view of more proximal (nearer the body) teeth. The bottom segment show the ventral view underneath the mandibles. That flap you're looking at is the labium that has three-segmented palps.

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This stag beetle has incredible mandibles! As they close they interlock in a jigsaw pattern. Tons of teeth on this one. Adult stag beetles don't eat much (maybe sap) so again, this male uses these giant mandibles to secure mating rights with nearby females.

The insect on the left is a walking stick! I think walking stick mouthparts are some of the coolest on the planet. I love how they overlap and almost gruesomely fit together into  puzzle box. The labrum is emarginated, which means it has a notch in it like the end of a petal or leave. When walking sticks eat leaves they chew on the leaves vertically, so that the edge slices up between the two mandibles an into the notch in the labrum. It acts as a guide to keep the leaf in 'optimal eating position.' That's a technical term.

Finally, the mouthparts on the right belong to a weevil beetle! Weevil beetles have long snouts but at the very, very end of those snouts there are tiny chewing mouthparts. Even though this weevil is huge, the mouthparts were hard to see properly even with the help of the Celestron FlipView microscope I use.

The stag beetles in this post got me thinking about sexual dimorphism, where males and females look different. I'm ready to cue up some dobsonflies for next week's #MicroscopeMonday!