Hi Cynthia, Bugs usually have a fairly narrow window of light, heat and humidity levels they're comfortable enduring. It's quite possible the aphids liked the temperature, air movement and humidity down lower on the columbine than they did up on the rose tips. I see this kind of thing frequently with aphids and other insects. It will be hot, dry and sunny in most of the garden, but in a protected spot where the air is more still, cooler and damper, I'll find aphids and/or saw fly, even up where saw fly don't live (supposedly). While they probably would prefer the rose juice, it could easily be too hot, too dry or too breezy for their comfort. Kim

Very interesting! I never noticed that. But could the stickiness of columbine pods be honeydew from aphids?

Different species of aphids have different hosts. For example there is a blackish cabbage aphid, and a large red aphid that likes tomatoes. The main rose pest here is the peach aphid.

That's what I was wondering could it be a different species of aphids that prefers columbine over roses...?
That was my first thought after reading the original post...

I'm not surprised there are different species of the little vermin with specific food hosts. There are for diseases and parasites, so why not? I'd think it highly likely part of the stickiness might be honeydew, though I remember finding the columbine seed heads being sticky on their own. It's been some years since I've grown any as they were wonderfully suitable for Newhall and completely unsuitable for more "tropical" Encino. For quite a few years, I collected different types of columbine for that garden. Quite a few were sticky, as if it helped the seeds to adhere to animals (and my hands), allowing them to travel. But most things infested with aphids tend to be quite sticky, too, so it could help. Kim

Thanks for the help problem solving guys! I did have to chuckle a bit at your California gauge of how tall roses should be by this time of year, Kim, given the assumption of different height and air patterns with the columbine. Sadly, after this brutal winter nothing but the climbers are blooming at anything above knee height after being pruned to the ground, which puts them at exactly the same height (and presumably same air patterns) as the columbine pods.

I tend to like the theory of the plant-specific type of aphids going on here, particularly since it's so all or none on the plants. These are definitely the actively crawling (green colored) aphids, not just the honeydew residue, though I'm sure stickiness has something to do with them staying put for now.

WHICH of course raises another question in my ongoing puzzled brain - are there aphid-species-specific predators then? Are the peach aphids tastier than these "columbine aphids"? If not, then what's up with my usual ladybugs and other good guys? The columbine infestation is heavier than I usually notice for the first flush of roses, and this level of aphid swarm would definitely get my attention if it was on my roses. Presumably the predator level has to rise to the level of the food to be consumed, but it's definitely a greater imbalance this year than I've ever seen. As I've mentioned, I've seen fewer ladybugs this spring than usual, though plenty of other assorted bugs, and I was wondering if the harsh winter cut the usual spring population back. Usually they're crawling out of the mulch as soon as I pull it back from the roses, and invading the house all spring, but this year I saw none in the mulch and only one in the house. I'm sure they have some dormant eggs that will hatch eventually, but the inquiring side of my brain that is no longer consumed with rose planting is pondering the other half of this equation.

It's interesting to know that the peach aphid is the culprit for roses, Michael. OK, one more curious question on that account - I recently planted a peach tree in my yard, which is a good 4 years from blooming and even further from setting fruit. Still, once it does bloom, would you guess that having the roses to attract the peach aphid hurts the peach prospects or helps because it also attracts the predators? Being mostly organic (aka lazy), I'm unlikely to do anything about it unless it gets particularly bad, just curious.

Cynthia

Predators usually lag behind pests. We'll have a particularly wet winter and the following spring the pests are legion. They respond seemingly immediately to the increase in resources (food). The predators lag behind a season or two, but eventually catch up. I'd bet your lady bugs were either harder hit by the conditions or are slower to respond to the improving conditions, as if to naturally make sure there is ample food supply before they do their things. Of course not "consciously" but by development. Kim