The Life cycle of an aphid
Winter is spent as a dormant egg, near a bud site on a poplar tree.
Around March, the egg hatches into a female (always), and the aphid starts feeding on the tree's sap.
At maturity she produces a brood of live young (without a mate). These aphids are genetically identical.
These young feed on the sap of the tree, and also produce clones of themselves in the same way.
Repeat until tree branch is full. It's sometime around May, most likely.
The next generation of female (still all female) aphids are born with wings. They fly off to an empty plant, not necessarily a poplar tree.
And start producing daughters. Until that plant is full up. This continues until the supply of aphid supporting plants starts to decline (September).
The next generation of females fly back to the poplar tree.
They lay eggs containing (more) females. No males yet this year... But this generation is ready to deal with them when they get here.
The aphids remaining out in the field, away from the popular, produce eggs containing winged males. These males head back to the tree, to meet and mate with the females.
Who then lay eggs near the bud sites on the popular tree, where they sit dormant for the winter.
This system allows the aphid population to explode during the time of plenty, but still enjoy the advantages of genetic reshuffling. Aphids are a r-selected species