Ants most definately eat butterfly eggs and 1st instar caterpillars (See below a section of an abstract). In fact, many plants, such as Senna, have what are called "extra floral nectaries". These are areas (usually little protruberances) that secrete nectar to attract ants. The ants in turn protect the plant from herbivores. There are lots of other things that eat eggs as well, ladybugs, tree crickets, lacewing nymphs. In addition, small wasps called chaclids, can lay their eggs inside butterfly eggs. This is why we often collect eggs and bring them to a safe place to raise. By the way, I have see a lot of chrysalises eaten by ants as well. They leave a nice neat hole, a little smaller than a pencil eraser. -Elisabeth Abstract I investigated variation in the effect of ants at extrafloral nectaries on the plant reproductive success among three populations of Cassia fasciculata (Leguminosae) in northern Florida. Results show that the possession of extrafloral nectaries can lead to increased reproduction. Density of ants and removal of experimentally placed Drosophila larvae were far higher on C. fasciculata than on nonnectariferous background plants. Ants preyed on eggs and small larvae of lepidopteran herbivores. C. fasciculata plants from which ants were excluded had more larvae of the major seed pod predator Phoebis sennae (Pieridae; Lepidoptera), suffered higher pod predation (at one site), and had lower reproductive output (at two sites) than did control plants to which ants had access. Effects of extrafloral nectaries on reproduction of C. fasciculata varied among the three populations, due apparently to differences in density of ants and potential herbivores.

Interesting you have none this year because last weekend mine was covered. I wonder if some particularly good southern winds just sped them further South than they normally get at this time of year, because they've never been early enough to feast on the heptacodium tree here. Usually they wouldn't be here for another two or three weeks. I'm in NE Pa and they started showing up last Saturday and continued to trickle in through Sunday until there were maybe three or four dozen on the tree. Then they disappeared on Monday as the rains of Florence moved through. Now a week later a few more are showing up, but it's closer to a dozen or so at one time so we'll see what this cold front brings. Your tree looks beautiful and the arch really sets off that part of the garden!

You gotta figure out whether your problem is OE or not. This requires a microscope so you can see whether the butterflies have the OE spores. If it is OE, then you need to start bleaching. If it is not OE, you may never know what the problem is/was. There was two years that all my monarch pillars died. I think it was me using too much MiracleGro on my milkweed but I'll never know for sure. https://butterfly-fun-facts.com/oe-ophryocystis-elektroscirrha-monarch-butterfly/

I have found the best thing to do is leave the Oleander aphids alone, and as they increase they will attract the predators that feed on them. Lady beetles, lacewings, and small parasitic flies and wasps. I will carefully spray any aphids off with the hose if they are on any of my rarer milkweeds that are still. small and not established are still small and not yet established. It's too much work and time to constantly be hosing off all your milkweeds, and you can end up damaging Monarch eggs or little caterpillars in the process. It's hard to see so many aphids on a plant, and not take action, but the natural predators will eventually come and clean out the aphids quickly. Most milkweeds have tubers that store energy, and they have evolved to be able to withstand a lot of predation from Monarch caterpillars, so it's doubtful the could kill a milkweed, except perhaps a very young seedling. Oleander aphids do not turn into red and black milkweed beetles, that's absurd. Hosing them off is reducing the food source of the predators. By leaving them, you help the predator populations, which will mean more predators and less aphids in the future. .