Daddy Long-legs (spiders) are often found inside homes in dark corners or in this case in an old shelf system in the garage. They eat small insects, spiders and silverfish. According to one book I checked they are introduced.
The eggs are held together in a bundle and carried in the mouthparts of the female until hatching. Looks like this female had a mouth full
They are apparently relatively harmless to humans so they a remain a good method of silverfish control. I just wish they would eat a bit faster as the silverfish seem to be winning.