aphids

Seeing ants crawling up and down a tree is how I discovered that the tree was infested with aphids.

Right;the novelty is aphids actually produce the caratenoids, they don't eat them.

The body colour of Robichon's lab aphids is affected by environmental conditions, with the cold favouring green aphids, optimal conditions resulting in orange ones and white ones appearing when the population is large and faced with limited resources....

Not quite the same thing you're talking about, but some ants farm aphids to eat something they produce.

People can die if an entire region's crop is eaten by locusts or aphids or caterpillars or whatever.

The ants defend an aphid from another creature that eats/destroys the aphids so that the ants can eat it.

Scientists at Rothamstead Research (an agricultural research institution) wanted to grow genetically modified wheat to deter aphids.

They even defend the aphids from predators and so forth, so it isn't a bad life for them either.

In the spring, the ants carry the newly hatched aphids back to the plants.

A few ants cultivate trees or fungi or aphids, but they seem to specialize in just domesticating just one species at a time.

For my protected potted/bedded plants i use a variety of natural methods to keep aphids and snails at bay, and they work brilliantly.

Some of the examples of ants and aphids seems to be happenstance.

The ants can't digest the leaves of the rhubarb, but the aphids can and excrete a sugary by-product that the ants “milk” from them.

They corrected the title: "Photosynthesis-like process found in insects": "The original headline of the piece incorrectly implied that the researchers had discovered evidence of photosynthesis in aphids.

Green aphids, which contain high levels of carotenoids, make significantly more ATP than do white ones, which are almost devoid of these pigments." Assuming the photosynthetic aphid hypothesis this makes for an interesting positive feedback loop with analogies in economics - when energy levels fall below a critical threshold the aphids are unable to synthesise the "metabolically expensive" cartenoids.

Yeah it's especially a bit humbling when you realize that the vast majority of critters are some form or another of carnivore/omnivore and there's only a trace few herbivores and they're all the "pests" like aphids that we are constantly doing battle with...