We love watching and learning about insects... I have 6 and 4 year old boys.
Last year I ordered a couple praying mantis eggs and they never hatched.
A friend of mine said she kept hers inside and misted them with water and they
hatched on her back porch in her warm weather. I perched mine in a screened
bug house during June in Tennessee and waited and waited..nothing.
I actually got them for my sons birthday and he said he wants a refund gift
this year because they never hatched.
The praying mantis egg I had worked out well. I kept it in the mesh bag it came in and hung it about 1' from the ground among some shady orange jubilee vines. I watered it about once a week only because its so hot here in AZ. Everything needs water in life, so I'm sure these eggs sacks need water also. From looking at them, I would say they are probably well protected to prevent drowning. You will know when the egg hatches because a big slit will develop from it and you should start seeing the litter critters around your yard. I seen 4 in my garden after that and I'm sure there were more. They were hanging out on my basil plants for a while but now I have not seen them in a couple of weeks. I hope the Insecticidal soap I had to spray on the basil didn't run them off. I found my Praying Mantis egg at Home Depot, next time they sell them I plan on buying 3 or 4 for my yard. Also the instructions on the bag said they would hatch when the temperatures reached 80F+ regularly. It was well into the high 90's here when mine hatched.
I wonder if the egg sack has to get wet to weaken it for the young to get out. As far as temp, we live in north Idaho and it does not get into the 80's here regularly until mid to late july, but we see tons of mantises as early as mid june.
I have a bunch of egg sacks in the house right now that female mantises attached to the walls by my plants, how long do they have to be in the egg sacks to develope? I know outside most of the eggsacks sit there all winter long for 6 to 7 months in the cold and wet.
I guess it sure wouldn't hurt them any to mist them down with a little water every day like the spring rain and dew would, I just have no idea how long they should be in the egg sacks before hatching.