Are there any arachnologists out there? Why do spiders show up in my yard in the fall? Where are they the rest of the year?

A good many started life in the early spring hatching from eggs, others blown in on small web gossamer's.

At first they are the size of a pinhead so largely go unnoticed. As they grow through the summer, they usually hide by day in shubs or curled leaves mostly coming out at night. Now, in the autumn, they may make their web and even stay out in the daytime, and of course being much larger, they are easier to spot.

There are still yet others that spent the winter hidden under tree bark and leaf litter, or burrowed under rocks or logs, and they might be spotted during the day.

Spiders like the orb weavers/garden spiders are getting ready to lay eggs and most of those will die soon after or with the onset of winter. The eggs being hidden will survive the winter and the cycle repeats early next spring.

I had a pretty garden spider two years ago near my drive, I was hoping some babies would stay around the next year, but sadly they all ballooned away, or may have been eaten by birds.

If you zoom in on the photo, you can even see a male with the female here:

https://www.flickr.com/photos/32083154@N02/6166267...

My European garden spider by the porch, she would come out at dusk to make her web, then eat her web before hiding out for the day:

https://www.flickr.com/photos/32083154@N02/6012444...

Bob's video of his orb weaver and releasing babies the next spring:

https://www.youtube.com/watch?v=emqItBG4oqg

The short answer is - they were too young and small before. They were around, but hiding to avoid being eaten. Now time is short - they need to eat a LOT before cold weather so they have enough bodily resources to lay eggs before they die. It's just their natural cycle. More here:

http://www.oregonlive.com/hg/index.ssf/2013/08/spi...