Who's holding a convention on my heliopsis?

I've never seen these insects before, but today I noticed them congregated by the hundreds on both of my heliopsis (two different cultivars several feet apart) and nowhere else. They're about the size and shape of aphids, possibly just a wee bit larger, and bright red. They're mostly on the newest growth, but also like some older backsides of leaves. They seem to behave like aphids, but beside being bright red, they also seem to have tougher bodies.
I sprayed the plants with a neem oil solution, and they just sat there, though some turned a darker color. I may have killed them, but it remains to be seen.

Does anyone know what they are, and how they may have found my garden? I've had heliopsis "bressingham doubloon for at least a few years, and have never seen these critters before. I got heliopsis "asahi" last year and it was also untouched by insects. And does anyone know any environmentally friendly way to get rid of them if the neem doesn't work?

If it looks like an aphid...they come in a multitude of colors including red so that's most likely what you have.

Ewwwww. Thanks, ecrane. You're probably right. I've only ever seen white aphids before, but I hate them because you don't (or at least I don't) ever notice them until there are thousands covering the plant. I usually end up just ripping out the infested plant, but I really don't want to give up my heliopsis.

There's white ones, green ones, brown ones, blackish ones, orange ones, red ones...a whole rainbow of aphids! LOL

My approach for aphids is to hose them off, and then sometimes if it was a bad infestation I'll hit them with insecticidal soap. The trick is whatever you use on them, you have to keep after them for a while. They reproduce very quickly, so if you miss a couple and then ignore them for a week they'll be right back all over everything. But if you're vigilant and keep hosing/soaping every couple days, you can generally get them under control.

I guess I should consider myself lucky not to have had the rainbow experience! I actually rarely have aphids at all (knock on wood), so I was dismayed to find the white ones had taken over a lupine the other day. I used a neem solution on that one. The white ones just seem to fall off, whereas the red ones on the heliopsis seem to be stuck on fast. I'll find out today if they'll hose off. Thanks for the advice. I'll get some insecticidal soap. I think I'm out. But my aim is eradication, not control. I don't want to have to keep after aphids all summer! It's bad enough having to keep after asiatic lily beetles.

You shouldn't have to keep after them all summer--usually I just have to keep after them for a week or two to make sure they're all gone. The mistake many people make is spraying and then not checking again for a week or two, and by that time the one or two you missed will have had time to build the population right back up again. And that's not just true for my hosing/soaping technique...with most pesticides (even nastier more toxic ones) you're going to have to take a similar approach of keeping after them for a while--you'll always miss one or two and then those can reproduce. The surest way to get them all in one shot is to use a systemic insecticide like Bayer 3-in-1, but since you asked for an environmentally friendly solution I assumed you were hoping for something organic and they aren't. Systemics get absorbed into the plant's tissues and stay there so any aphids (or anything else) that comes along later will be killed when they suck on the leaves.

Thanks, ecrane. I hosed them down today and didn't see any survivors, but I'll definitely keep vigilant!