Aphids are fascinating (if annoying in the garden). They are capable of telescoping generations [1] which means an aphid can be pregnant with an aphid that is also pregnant.
For months, I've had an Argentine ant problem, as in an infinite side-by-side congo line of them marching from my living room to my kitchen.
I tried a bunch of things; the number #1 liquid ant borox bait trap killer gizmo on Amazon just made a bunch of them die, but it didn't kill the colony. I just kept laying out more and more traps, but the ants would just die and fill up the trap, then the other ants would somehow learn that the trap was bad, and never touch it again, but interestingly enough, they would go in, and carry away their dead comrades.
Apparently, because Argentine ants have multiple queens, forming a giant macro colony that vertically spans the entire state of California. You get one queen, and they won't be down for the count, they'll just come right back. These are stubborn, resilient little buggers.
I then tried caulking the cracks along the bottom of the sheetrock next to my windows that they would keep coming out of, and I sealed that whole thing up good; it worked for about a week, and then the ants managed to eat through the caulking!
Anyhow, there were aphids were all over the vines(?) going all the way up the side of my house and up over my window. Once we removed the vines entirely, the ants were gone for good.
Sorry about the incomplete sentences and run-ons, I'm tired...
Mugwort is invasive, causes allergies, and is probably the single most-common street weed growing in NYC. So probably not a huge problem for the aphids to kill as much as they can.
The cooler story about aphids though is the dancing wooly aphids, which should be starting to colonize beech trees right around now. In addition to dancing when you shake the tree, there is an entire species of fungus that grows only in the honeydew left by the aphids. These are the black masses that you see on pretty much every single beech tree:
Ants are incredibly impressive creatures, that appear to have been engaged in activities we usually consider to be uniquely human. Their history of agriculture, "animal" husbandry and city building, not to mention some clever air conditioning solutions predates our existence as modern humans.
Impressive little creatures when you get them in a group, and they're almost always in a group.
African termites' engineering is quite impressive as well. Their mound is a giant, self-cooling fungus farm! It was a source of inspiration for biomimetic architecture. You can read about it here: http://inhabitat.com/building-modelled-on-termites-eastgate-...
The termite's task in temperature regulation almost seems impossibly difficult. You would need an extremely well educated and specialized human to develop something to match what they've done.
On the other hand, HVAC (I mean, that's what it is right?) must confer a huge advantage, even in its relatively early and primitive stages. You probably save loads of energy with even a degree in the right direction, especially when you're raising lots of larvae.
Like the first critter to evolve a couple of photosensitive cells, it seems like a minute thing, but telling dark from light can be a huge leg up. Now we look at complex eye structures and are amazed, but of course they were once eye spots.
I suspect that it might be the same with the termites, who have after all had a long time, and uncountable generations to select for these traits.
Not necessarily: The article states that ants are deliberately maintaining aphid herds, possibly for many seasons, by carefully selecting for a ratio of red and green insects. The wording of that statement implies intent and intention on the part of the ants.
Except for the fact that we don't what the ants are doing at all. It may simply be (and likely more likely be) that over many, many generations of ants, evolution, a purely random, intentionless process, has resulted in ants with a preference for the 2-1 green-to-red ratio.
The ants aren't selecting or managing or farming. They are pruning the herd to match the distribution encoded in ant DNA, an encoding arrived at over many, many generations, but simple random mutations conveying slight survival benefits.
It's hard to beat insects in that way, because they can iterate generations so quickly, and a single beneficial mutation can turn into a mutant population almost overnight. Regardless though of how it comes to be, the behavior itself is impressive when you consider what an individual ant brings to the table.
I've been battling aphid farming ants in my garden for years now. It's kind of fun to watch them tend their aphids but they wreak havock on plants. I've used diatomaceous earth to repel the ants. It acts like tiny shards of glass that gets caught in exoskeletons. The ants hate it. But it's ineffective of it gets wet. I'm interested in trying Tanglefoot. Anyone have experience with this product?
Permaculturists have been using physical methods for years to stop ants protecting aphid herds -- you may not need any chemicals at all. Hunt around for some half-donut shapes that clip around the trunk that you can fill with water. (I can't find any pics after a quick search, but I know they exist.) Otherwise, maybe something mild like a vaseline barrier - probably need to protect from the rain, of course.
I think its crazy how they guard the "live stock". Touch a leaf near an aphid and you will have 2-3 ants on your arm almost instantly.
I've even seen ants guarding plants that don't even have any aphids on it yet.
Aphids can grow wings but ants clip them to prevent flight?!?
Amazing microcosm, it reflects what humans do at a much smaller scale. Makes me seriously wonder what types are larger structures there are out there in the universe.
https://simonleather.wordpress.com/2013/03/19/living-inside-...
They also can grow wings if the colony gets overcrowded or the plant they are on is starting to die.
[1] https://en.wikipedia.org/wiki/Telescoping_generations