Slings, I fill the enclosure up about a third with substrate. I usually add a small piece of cork bark and a few sticks. I usually avoid water dishes at this age and stick with misting as a water source. Suntiger slings will spend a lot of time burrowed into the ground or will web up the area where the cork bark and ground meet making a dirt curtain with substrate or moss and stay well hidden. Juveniles (over 2-2.5 in.), I place a piece of vertical cork bark to the side of the enclosure, or just lean it at an angle and provide about 2.5-3 in of substrate. I will start introducing a water dish depending on enclosure setup. I set mine on substrate or will set it up flush to substrate so its like a little pool. Expect at time for them to flip, drag and web over. So, I still recommend misting as well. I over flow the water dish so the substrate retains a little moisture, but avoid overdoing it as it could lead to mold growth. Adults, I set up about 3-4 in of substrate and hollow cork bark and a few branches.
As far as feeding, I give my spiderlings small roaches or crickets until .5 in. Once they reach .5 in, I just drop in a small cricket twice a week. I will wait about 3-4 days after a molt before trying to feed them again. Juveniles over 2.5”, they will get 2-3 medium crickets every 5-7 days. This will depend on the size of the abdomen. Adults are served 6-10 large crickets every week. Adults will usually get 1.5 to 2 weeks of recovery time before I try to feed them after a molt. You can also try mealworms, roaches, or even horned worms.
Irminia can be defensive in my experience. They are very fast and will teleport from one side of the enclosure. In fact, their venom is stronger than most New Worlds, This would be an excellent species for anyone with some experience with New Worlds and begin to make the transition to keeping Old World tarantulas. Providing a great hide or hides will provide them security and more likely to run for safety than showing of their pretty fangs.
Reports online state their venom has reactions like vomiting, sweating, lightheadedness and muscle-spasms for a couple days. However, most say that aside the pain of the extremity the bite happened on, all symptoms were gone the next day. Again, a bite is something you really don’t have to worry about if you have a proper set up, warn the tarantula before crossing into its space. Irminia can be very seclusive by spending weeks in hiding. When they do come out their stunning colors will leave you in amazement.