Ladybird populations can vary enormously in the same garden from year to year. If the winter is mild, lots will live through it and your garden can be literally crawling with them in early spring. They then mate, lay eggs and most will then die, but their larvae (like Marshmello shows) will hatch and eat aphids voraciously, so much so that they may have trouble finding any aphids at all. If that happens, many will die before they reach the stage where they glue themselves to a leaf and turn into adult ladybirds in late summer, so the next year you may not see many about in early spring. It's a cycle many predatory animals go through, known scientifically as Predator-Prey Dynamics (or more commonly "foxes and rabbits".)
