On aphids and ants

 

If you were an aphid, you'd think that your job was to suck sap from trees and plants and reproduce.  Their story is strange enough as it is, because almost everything they consume they excrete.  But to ladybugs, aphids are food.  And, for ants, aphids are cattle, protected, shepherded and milked.  

Read this account of the strange and complex relationship in The Hidden Life of Trees by Peter Wohlleben:

Aphids (sometimes also called plant lice or greenflies) are much lazier than woodpeckers.  Instead of flying about industriously and hacking out holes here and there, they attach their sucking mouth parts to the veins of leaves and needles.  Thus positioned, they get royally drunk in a way no other animals can. The tree's lifeblood rushes right through these tiny insects and comes out the other end in large droplets.  Aphids need to saturate themselves like this because the sap contains very little protein -- a nutrient they need for growth and reproduction.  They filter the fluid for the protein they crave and expel most of the carbohydrates, above all sugar, untouched.  Little wonder it rains sticky honeydew under trees infested with aphids.  Perhaps you've had the experience of parking your car under a stricken maple only to come back to a thoroughly filthy windscreen.

For many animals, however, sap-sucking pests such as aphids are a blessing. First, they benefit other insects such as ladybugs, whose larvae happily devour one aphid after another.  Then there are forest ants, which love the honeydew the aphids excrete so much that they slurp it up right from the aphids' backsides.  To speed up the process, the ants stroke the aphids with their antennae, stimulating them to excrete the honeydew.  And to prevent other opportunists from entertaining the idea of eating the ants' valuable aphid colonies, the ants protect them.  There's a regular little livestock operation going on up there in the forest canopy.  

The natural world is filled with examples like this.  If you just look at a bit of the relationship, you see something relatively straightforward.  But if you pull back the viewfinder, you see something much more wondrous and complex.  And it's more complex than "the food chain" -- it's not just that simple.

The world is like that, interconnected and unexpected.  You can think of yourself as the aphid, the ladybug, or the ant.  And probably, we are the aphid, slurping the sap while we are, oblivious, both protected and being used by others.