Is it safe to delete photos that I saved to a thumb drive?

I have no space on my phone (iPhone 5s if it matters) so I used my charger to hook my phone up to my laptop and copied all my pictures into a thumb drive there. I want to delete all the pictures on my phone now, but I'm really worried. These pictures have so many memories that I do not wish to loose, so if I delete them will they still be safe on my thumb drive?

Thumbdrives can fail, so if you want to be safe, make another copy (to another thumbdrive, another harddrive, burn to disc, etc.).

IF they are really on the thumb drive AND you have stored the drive in a sure place, they will certainly be more secure than on the phone. But you should have more than one copy of the photos and they should be in two different places. A good idea these days would be have one copy each on the WEB somewhere with a GOOD password.

Ethelred Hardrede