Unwelcome aeronaut

When I noticed a colony of green aphids on a columbine plant it was the single winged individual on top of the bud that caught my attention. I wondered why just the one had wings.

The aphid life cycle is profoundly interesting. The first generation to emerge in the spring from overwintered eggs are all female and they then proceed to reproduce parthogenetically (without male intervention). Their offspring are all female too, clones of their mother. Each female lives for around 25 days during which time she can produce 80 or so live babies. Hence the variation in size you can see on the stalk here. Each baby sheds its skin (more correctly, its exoskeleton) 4 times before it is full grown -  visible here as pale husks.
Obviously the aphid population grows rapidly (although they do have their predators) and when  saturation point nears a generation of winged aphids is born that can fly to another plant and start a new colony.

As autumn approaches a generation is born that includes males. Males and females can now reproduce sexually and produce the overwintering eggs. It's no wonder that with such an efficient system aphids are the massive problem they are, sucking sap from their host and spreading viruses.  (An observer from a far distant planet might say the same about the human species.)

Soapy water is the safest form of deterrent although ladybirds do an excellent job if you have them. Or you can order them! I found this poem by Christy Ducker

Instead of a way out
she finds a sack.
It arrives at the greenhouse
each Thursday.
Once set down,
the sack fidgets
until she pulls open
its neck,
and pours out one kilo
of ladybirds.
For a moment,
she sees only
stunned treasure
hissing to a standstill.
But soon
the ladybirds fly
whirring.
Hunting, they stud
the soft hurt
of tomato stems.
At night
they fall from her clothes,
brilliant
even in darkness.