Greenflies

I found out that greenflies give birth to live young which are all female, and all pregnant.  They then give birth to more pregnant females.  Then when the weather starts to cool down in autumn they give birth to some males who they mate with.  They then lay eggs that last over the winter and hatch in the spring, when it all starts again.  Some will grow wings to fly to new places to colonise.  You couldn't make it up!