Hi
Most of the hispida in America and Europe were supplied by me.
I have exported Atheris for the last 8 years from East Africa.
The main diet of Atheris hispida certainly are slugs. They may take the odd Hyperolius reed frog but its not their main diet.
In Uganda I feed the hispida on local slugs which are less than 1 inch long and greyish in colour. They come up to the snail and just in slow motion grab the snail and then swallow it in a "chewing" motion in less than 5 seconds. They exclusively feed on them at my place. I have tried almost everything else from Invertebrates to baby birds (Finches) to Frogs, Small live fish and tadpoles, geckos.. im talking everything u can think of.. and its a waste of time. They eat slugs.
My close friend in Europe who is keeping 5 pair of my hispida has tried to feed them with European snails and slugs and it will not work. There may be a difference in smell or taste between different species of snail I am not sure.
However they can get used to pinkies. In the beginning it really takes allot of patience but if u are a little bit familiar with tease feeding then you will be surprised. He has them so far that all he needs to do is tap them once on the head with a pinkie and they take them off the forceps and in the usual manner "chew" them down within seconds.
If this doesnt work another very good way is to hold the hispida (Only do this if U know what U are doing !) as if you were to force feed it.. and just tap a dead one day old pinky on its nose a few times.. the hispida normally will grab the pinkie and swallow it as usual within a few seconds. Make sure to always use as small as possible pinkies for this. I normally soak the dead pinkie in water for a few mitutes before I do this so it is swallowed easier. After doing this a few times the tease feeding should work allot easier.
Another important factor is ventilation. NEVER keep a hispida in a warm damp and poorly ventilated cage.. this is how U will ruin the Lungs of the poor little fellows. Keep the very well ventilated in the manner you would keep a chameleon.
I keep them in a wooden frame measuring 4ft x 3ft x 3ft covered with soft synthetic mosquito net on all sides. Allot of thin branches and a water dish (altought they rarely drink from the dish). Do not keep them damp. I spray them and the entire cage every 3 or so days with water in the EVENING. After this they often will be strolling around the whole night. Thats when I feed them.
Another factor are the temperatures. It is not important for them to be cooled too low at night. We collect them at 1500 meters altitude (about 4500 feet) and minimum night time temperatures are around 15°C (I guess that is somewhere in the upper 60s). Now the important part is not to keep them to warm in the DAY. Maximum temperatures should be around 24°C (I guess again that this would be in the upper 70s)and we only offer them a small spot light in a corner pointing at a few branches so they can heat up a bit during the day. If U keep them warmer they may have problems with digesting and regurgitate.
We currently have 3 gravid females in Europe and are hoping to get healthy captive babies by the end of this month.
I hope some of this information can help u.

Price Reptiles International