Aphids

I purchased sterile potting soil. I planted seeds. I am now overrun with a plethora of aphids. Where did they come from? Unless the aphids spent the Winter hiding under the bed, I have no idea where they came from.
The army of ladybugs that I have been dealing with for two months have all deserted. They must have all joined the volunteer fire department in their home towns and are now busy saving their children. Their beloved little children, who have an enormous appetite for aphids, would be more than welcome here while their home is being rebuilt.
I have been taking each plant outside and brushing off the aphids as I have a reverance for living things that precludes crushing or poisoning them. This reverance does not always include spiders. HMMMM, do spiders eat aphids? I find it hard to kill anything but to allow Nature to handle the situation seems acceptable. Morals are determined by the society that we live in but ethics are a personal choice.
"Ladybug, ladybug, fly away home. With an aphid under each arm!".