Cool things you didn't know - 5 - breathing using a plant for air: Plateumaris

I believe this is an adult reed beetle - genus Plateumaris - on a yellow iris flower.

Have you ever heard of an insect breathing underwater by using the air inside aquatic plants?  I have heard of it, but never researched it until now.

Reed beetles, like the one above, have two distinctive habitats.  As larvae, the insect attaches to underwater plant parts such as the yellow iris in the photo.  They feed on the roots and stems of the host plant, but the peculiar thing is that they get their oxygen from the plant itself.  They tap into the aerenchyma (air-filled tissue) of the plant using two spine-like hooks located on the abdomen.  This allows gas exchange to occur with the insects' breathing apparatus (malpighian tubules).  You can see the two spine-like hooks in the image below (lower left image).  Taken from this source.

Have a look at lower left image - reed beetle grub showing the breathing hooks.

The adults live above water and look and behave similarly to other beetles.  They are technically leaf beetles, not long-horned beetles, despite their long antennae.  As leaf beetles, they eat the leaves of aquatic plants that are above water.  After mating, eggs are laid above the water with a jelly-like covering.  After hatching, the young larvae descend into the water and begin their life attached to the plant, requiring four or five moults before pupating.  

There is another interesting fact about these beetles, where symbiotic bacteria are used by the pupating larvae to produce the cacoon.  The bacteria are mixed in with the jelly-like substance with the eggs and follows the insect through all stages of life.  It's another remarkable thing.

Thanks for reading.

Eric Svendsen     www.ericspix.com