i'm not sure how or if ants will affect the frogs but they are definitely a danger to cresteds (cresteds don't produce the antihistamines to fight ant bites and a lot of bites can actually be fatal). in any case, you can't just allow them to stay.

first, get your crickets out of the box and into something that the ants can't get into since that seems to be what they are the most attacted to. they will swarm any dead or dying crickets as well as whatever you are feeding them. i use a setup like this for my crickets but you can make something similar with a rubbermaid, just make sure to use screen for part of the lid to provide enough ventillation: http://www.armstrongcricket.com/polyk.htm.

you will have to strip down your frog tank and put in all new substrate and replant the plants after washing them to get rid of any ants that might be on them. i know that's a pain, but you have to get rid of the ants that are already in the tank. you then need to come up with a way to keep the ants from getting into the tank--it's an aquarium right? ants can't climb glass so they must be getting in another way. make sure the aquarium is not against a wall or anything else that the ants can climb and then get onto/into the tank from.

to get rid of the ants that are inside now and coming in and out i recommend terro gel ant baits. i found these at lowes and they work great: http://www.lowes.com/lowes/lkn?actio...300&lpage=none. it takes a few days for the ants to get into the gel and distribute it through their colony but after about 3-4 days of a major ant invasion this summer in my herp room they haven't returned since i started using these baits.