Hi,
For the fruitflies, there is a simple way to get rid of them without insecticide or dangerous products. You simply have to make a trap. First, take an high container (for exemple a jar or a bottle of wine), then, make a cone with a sheet of paper (you can put a staple or a tape so the paper will stay in that shape). Then, you can put a piece of fruit (banana, mango, etc) in the bottom of the container and place the cone in the opening of the jar.
The flies will go in the container because they are attracted by the fruit, but they won't be able to come out. So, when they are trapped, you can let them free outside your house or kill them by freezing. Also, some people use beer instead of fruit. You should put this trap near your crickets container.
I have a lot of fruitflies sometimes, and this trap really helps to get rid of them.
I put a picture of my trap... Hope this helps!

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Lisabeth
1.1 Bearded dragons (Flake and Rusty)
1.0 Uromastyx geyri (Spiky)
1.1 Guinea pig (Pumpkin and Moka)