Wasp Invaders Repulsed by Aphid-Farming Ants as The White Rose Loses Colour

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I was out in the front garden sunshine, looking at the rose bushes which were once laden with petals and bright colours or otherwise bubbling over with raindrops, but now stood rather forlorn, devoid of much of their leafy clothing and blossom jewellery. There were still some white roses in fading bloom but most of the buds being unable to find the energy to burst into petal, had turned dry shades of brown.

Presently I spotted some ants climbing up and down the stalks and across the leaves. I hadn't previously noticed any ants, perhaps they'd been there all along. "But what are they doing up here?" I wondered, as I went to take a closer look.

Dotted around the bush in about half-a-dozen branching nodes, were some odd-shaped clusters and it was here that ant attention was being focused. Upon closer inspection the clusters appeared to be bodies of aphid-type creatures as well as what to my naked eye looked like eggs, or perhaps smaller baby aphids. At first the clusters appeared lifeless - dead and dry like the flowers. Aha, "ant food", I thought to myself. However, I observed some movement from the larger aphids and came to the conclusion that these clusters were indeed alive.

What were the ants up to? They weren't carrying the aphids away, nor were they eating them. If anything, they appeared to be managing them in some way. For example, I observed a couple of the aphids separate themselves from the huddle and start crawling off, but the ants nudged them back into position. One ant had even perched itself on top of the pile of aphids, not seeming to be doing anything. "What's going on?"

Aphids are sucking insects that are common on both outdoor and indoor plants. They feed on the sap of plants and secrete a substance called honeydew. This sticky resin is a favorite food of ants, who actually “milk” the aphids for it by stroking their abdomen. The relationship between aphids and ants is symbiotic in that both receive some benefit from the arrangement.
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I had a quick look online and found the above information which confirmed that the ants were indeed not using the aphids as food, and instead were farming them for food. Perhaps they were milking them for insect narcotics, who knows! Parts of the bark near the aphid cluster had been stripped, presumably by the sap-suckers, and the ants certainly did seem to be tending to their livestock. I was aware from David Attenborough et al. that such relationships existed in Nature, but it was quite something to discover such fascinating activity for myself, and just outside the front door too!

Shortly after spotting the clusters, I noticed that there were a few wasps flying around the rose bush, also appearing to take an interest in the aphids. There were only two or three of them and they flew in and around the foliage, sometimes settling on a leaf and crawling around, drawing ever closer.

What then ensued was pretty dramatic and I, lost in fascination and clickety-clicks, didn't quite realise the full extent of what was going on until a later when I had done my research and put two and two together regarding the role that the ants were playing. Anyhow, the war-drums had started beating by this time, the opponents sizing each other up as Wasp approached the Defenders of Aphid.

I observed the following drama unfold numerous times, with variations. Wasp would approach and land on a leaf adjacent to the aphid cluster, occasionally on the stalk itself. Immediately one, two or more ants would climb down from the stalk by the aphids and charge the intruder. The ant numbers were few, no more than around 10 per cluster. They eventually took to patrolling the leaves in ones and twos. It was amazing to watch. Wasp only ever came alone, never in twos. The ants would dart forward - going for the legs I think - and Wasp would take flight or back off. At times Wasp would lunge forward and make an attack - its formidable jaws easily able to slice Ant in two. I didn't notice any successful wasp attacks, although some of the ant numbers did seem to go down, chopped in two I imagine! I saw ants overturned in battle, limbs flailing. Yet barely was Wasp ever allowed near the aphids, for the ants - kamikazes to the end - always managed to chase it away.

A fruitfly came to inspect the action, pretending with its colours to be a wasp and looking to see if there was opportunity to be had. It took some passing interest in the aphids then darted off to consider the fact that it wasn't armour-plated like Wasp, and if Wasp couldn't get past Ant, well what could a cute little fruitfly do eh?

Wasp kept it up for a while longer, dancing away with the ants and getting no nearer to accomplishing anything. It seemed possible to me that instead of wanting to eat the aphids, the wasps might have been after the same juicy (intoxicating?) honeydew that the ants were farming. The wasps kept trying, but the plucky little ants would not let them in on the feast!

Finally, a tranquil ladybird decided that enough was enough, and, as she descended a blade of grass, peace simultaneously descended on the battleground of Rosebush Farm.