Well, I am definately the person you want to talk to. I have raised thousands of these guys that laid eggs in my pool this summer and took over my yard. My pool is yet again filled with tads and I am in a bad postion of what to do for them.
Getting back to your situation, where and what do you have them in?
Can you take a few pics with a coin or hand etc. in the pic for size reference?
The froglets I have love their fruit flies and depending on the size of the froglets will easily eat fairly good size crickets, you'd be shocked what they can get down! I beleive the size of the crickets should be the distance between their eyes, but I am very new to this too and am not 100%, but I do believe that one of the articles on this site does explain it. I have noticed, however, that they can manage crickets that are larger than 1/2 their size and even slightly larger, but a pic would help me judge.
As far as the fruit flies go, I went to Josh's frogs, which most people here have recommended to me(Joshsfrogs.com there are links on this site). They also sell containers and medium so you can culture your own ff, or can buy a container already set up with thousands for about $3. plus about $7 for s&h. They also sell crickets, waxworms, etc. too if your interested. I feed mine wax worms too only on occasion because they are high in fat.
I'll be online at this site for a while longer if you have any more questions or can post a few pics. I am usually on every am for a few hours if you need any help.