Monday, January 6, 2020

The Ant and the Lacewing

As I was editing a series of photographs of acrobat ants (Crematogaster sp.) patrolling a stem of Verbesina virginica covered with aphids, I saw a small insect land on my Macbook screen and stay there.  I took several photographs of the screen and to identify it as a green lacewing.

Then as I enlarged the photograph the irony struck!  The lacewing was watching me edit pictures of an ant carrying off a decorated lacewing larva!  I could only imagine its horror in seeing the onscreen carnage of its kin.

Verbesina virginica or white crownbeard is a plant that covers the edges of our fields, filling in the untended areas between the rows of riparian walnut plantings.  Its other common name is frostweed, named for the delicate ice ribbons or "frost flowers" split out from the base of the stem with first winter freezing weather.  This will recur with each freezing night unless a prolonged cold spell freezes the roots.  This topic has led to multiple blogs on the subject, and here comes another one!

Back to the acrobat ants.  They patrol the 3-5 foot tall stems, protecting the aphids that cover the flower heads and upper stem of some of the plants.  Aphids suck out the plant sap and put out a sugary secretion called honeydew and many ant species will literally farm their ants like cattle, protecting them from harm by patrolling up and down the plant.  They get their sugar high from "milking" them in return for the protection.

Green lacewing larva sucking on aphids
Green lacewing larva also love aphids, but more for the "hamburger" than the milk.  Although they will also feed on caterpillars and some beetles, they are called "aphid lions" for good reason.   Grasping the tiny aphids in the tips of their large, curved, hollow mandibles, they suck out the body juices.  Once they become adults they will have chewing mouth parts.  The adults feed mostly on nectar, pollen, and honeydew but with some species the adults will feed on insects. 

Aphids are not only juicy and soft bodied but they usually occur in large numbers.  A lucky lacewing larva who encounters them will start sucking their juices like scattered liquid M and Ms.  This is where the acrobat ants come in.  These are not your gentle vegan ants described above.  The Crematogaster sp.  are predominately arboreal, climbing all over plants and trees, earning the name acrobat.  They are also called cocktail ants for the way they raise their abdomens when alarmed.

According to Wikipedia  "Acrobat ants acquire food largely through predation of other insects, like wasps.[5] They use venom to stun their prey and a complex trail-laying process to lead comrades to food sources. Like many social insects, they reproduce in nuptial flights and the queen stores sperm as she starts a new nest."  Our specimen above had a tight grip on a larva with helpless mandibles flailing against the ant's thorax.

As a reformed scientist I try to not anthropomorphize or put into human terms the feelings of insects that we think are living at a much less cognizant level.  I suspect the green lacewing up on top was just looking for a place to rest on my laptop screen, but I can't help thinking, "What would it think if it could see the screen?"