It looks like a bug attack IMO i have no idea what you need to do because i dont know the bug... im sorry :(

Hi djc6535 your dahlia looks like it has leaf minor, which is a burrow into the leaf leaving trails inside the leaf like your plants show. Systemic insecticide will often kill them though not sure what is available in your area? Here in Australia Rogor insecticide is often used to get leaf miner & as Wikipedia explains there are many lava which cause this problem. Good luck Here is a link that might be useful: Leaf miner

To post a photo you need to put it up on some other site. Many people use http://photobucket.com/, I personally use http://www.flickr.com/ Once you've got the picture up, you can then put a link to it in a message here. As far as the marks on your foilage, it certainly does sound like spider mites. Especially if the leaves are shriveling up as well. Cheers, Russ

I cant give solid advice, but I had a similar thing happen last year. I picked up two Dahlias in baskets, they were small collerette types. both got sick and slowly died. They started with leaves yellowing , then curling and drying up. One of them was completely dead by fall and I just tossed it, the other managed to hang on, but I was not able to get the tuber to eye up this spring (and I was successful with over 100 other tubers). While I have had insect damage and even a little fungus on my orchid dahlias, I have never had anything like this happen before. My assumption was that being a relatively new dahlia type they were susceptible to something I havent seen before. (and hope I dont see again!)