Root aphids are damn near exactly like cabbage aphids. Cabbage aphids DESTROYED a good 30lbs of a specialty cauliflower crop I was growing for market. There are no organic treatments for cabbage aphids, only physical barriers are effective and we're talking about row covers, buried all the way around. These species of aphids have two major life stages, the aphid stage, which if I recollect is a juvenile stage, and the flyer stage, which are the adult, pregnant females. IIRC, there are other stages, let me do some searching. But, the point is that RAs do have a flyer stage, and that only occurs when the infestation has become more advanced. Which is, as it so happens, also about the time that a grower really notices there's a problem.
Now, this is specific to Phylloxera. There are many species of root aphid. There are RAs that affect conifers, RAs that affect beets, corn root aphids, and so on. I'm not sure, but I believe that all other species of aphids can have a winged form as well. Don't hold me to that though!
From what I understand, & it's kind of in the picture, RA's (I am being extremely general here, there are tons if different types, you were being very specific) is that they will stay underground until they have exhausted a food source. They prefer to stay underground, so if they can move to another plant they will. Which may explain why I have only ever seen them above, or below the soil. I have large garden beds, so they have no problem moving on to the next plant. I have never seen them coming from above & going down underground, or the reverse. I'm also only speaking of outside vegetable gardening. The only pest I've ever had inside is a cricket. & I'm still trying to catch that sob.
Anyway, I was under the impression that most will stay wingless, unless to survive, a female will develop wings to establish another colony. It is not understood exactly how. That colony, the way I have understood it, will now be above soil, but will also be wingless, until a food source is depleted again. At which point a female will develop wings & go establish a new village.
In other words, some of them, take it upon themselves to develop wings, but simply to move & procreate somewhere else, if there is no where else underground to go. Once the flyer establishes a new colony, they will also be crawlers. Until a food source is depleted again. So becoming a flyer is not in the life cycle of, I believe, most aphids. A female will become a flyer, simply too move to another food source. But you will not often see them.
It is extremely possible, that I have just never observed crawlers emerging from the dirt, but from the many that I have seen, they seem perfectly content to stay down, or up, depending on how they got there.
http://www.backyardnature.net/aphid_lc.htm
**Edit, so you are right, in my opinion, they almost all have a winged form. All I'm saying is ending their life cycle in winged form is the exception, not the rule. Only some of them can even do it, & if they don't need to move to eat, they won't.
Unfortunately, they reproduce so rapidly, that if you have a small crop, flyers are likely to develop. & if you are in a tent or inside...they only have one place to go.
That's why I asked if the OP was inside or out, & why I suggested, if possible, get rid of that plant & get on damage control asap. The only way I personally would not toss that plant, was if the infestation was already in all of them.
