Aphids indeed. It has been one heck of a fruitful year for these buggers (no pun intended lol). I've been fighting them for the past few weeks myself.. I've made an effort this year to focus more on beneficial plantings to draw in more natural predators.. Planted a nice bed alongside the hoophouse with a dozen or so borage, coreopsis and russian comfrey.

Washing them off is effective, but you want to be mindful in regards to wetting the foliage of tomatoes more than necessary as it promotes foliar disease. Your best bet would bet something like Safer Soap or just squishing and brushing them off by hand.. As the season wears on they will dwindle in numbers as the predators increase in number.. The key is just keeping them at bay until then..

If the plants aren't near any cracks through which they can get into your house, I recommend buying and releasing ladybugs onto them. Wait til sunset, mist the leaves lightly with water, and turn the bugs loose. I had some clean off a 6' star jasmine of aphids by morning.

Umm; they're on a rooftop. I assume it means they are outdoors on that rooftop.

Thanks so much for the info/advice. I ended up brushing them off by hand (actually used a toothbrush) and after a few days, the results seem to be promising. Hoping to avoid having to add/spray anything so I'll continue to monitor and remove as needed. Thanks again!

You can spray w a diluted water solution of 1 gal water + 2 T dish soap + 2 tsp any cooking oil. Leave on for 1 hour then rinse off. May need to repeat the next day. Aphids travel by the wind (just carrying them to your tasty flora) so you'll get them frequently if you're growing by organic methods. I don't mind. I'm fussing over my tomatoes daily due to cutworms (the Devils of tomato plants). Removed 27 this weekend on 5 pots!?

Dish soap is a bad idea if you're not careful to use a true soap, rather than a detergent. I use Dr. Bronner's unscented.

Sweet alyssum, herbs that you let go to flower, and other plants that produce lots of small, open flowers will also attract aphid predators including little parasitoid wasps and hoverflies. I interplanted such flowering plants and herbs this year. The only aphids I've seen for weeks on my plants are the occasional mummified bodies of parasitized ones or winged aphids that are dead or lethargic.

I think that using water is probably better overall than insecticidal soap. A strong squirt bottle of plain water on a dry, sunny day knocks off the aphids, and the water dries super quickly. It's not like soapy water is any less wet than plain water, and there will be less harm to soft-bodied beneficials like hoverfly maggots with plain water. If your foliage is rugose or hairy, give it a shake afterward to knock off large water droplets, as there's something about the way the droplets collect on rugose or hairy foliage that can burn your leaves. I haven't had issues with normal, flat foliage that allows water to run off more easily.