You might want to give something with a lot of protein and fat. I read crickets will eat each other if they don't get enough protein. I have great sucess keeping crickets alive for weeks. The food I used are chick mash, crushed good quality dog kibbles, and tropical fish flakes. All these food mentioned are very high in protein and other stuff like calcium and other vitamins and minerals. Use these to powerfeed the crickets to boost the nutritional value of your crickets and your will see the difference; the crickets will actually live longer. One time I bought small crickets for my leo hathlings and they surived for 2 months before being all fed to my animals. I actually had to buy more because they grow so fast on the stuff and I just fed it to my larger lizards and frogs. For moisture I use a very shallow water dish, but this is for small and large crickets, the pinheads may actually drown in it, so I suggest you keep several fresh apple slices in there with the crickets instead. When it starts molding, throw it out and put in new ones.
And on other thing, you may need a bigger cage for your crickets. I hear they will kill each other if they don't have enough space. Get a ten gallon, which is cheap, and a screen lid. That should work well. Make sure you have plenty of ventalation, especially in this hot weather. From my experience the crickets survive better with a well ventalated cage. Good luck to you!