There are many ways in which to incubate eggs. The basic premise is the same: keep the eggs in a draft-free container at a steady temperature and humidity. The temperature and humidity are different for each species. Some variation (day/night) is usually OK, as long as the minimum and maximum temperatures are not exceeded. In some reptiles, such as turtles, the temperature influences the sex of the hatchlings.
The basic ingredients of an incubator are:
A way to keep the container warm
A thermometer to check the temperature
A substrate for the egg
(Optional) A thermostat is extremely useful
Below are a few methods that I or friends have used successfully.
Whole in Dirt
If your turtles are outdoors and laid their eggs in a place that is not totally unsuitable from a human point of view, simply protect the nesting site with a wire cage (made from chicken wire, for example) and let the eggs incubate naturally.
You can do this indoors, too, but need to remove all turtles from the enclosure as otherwise they are likely to accidentally dig up (and possibly eat) the eggs.
Yes, if you live somewhere where it’s warm enough, you can put moist paper towels into a deli cup, punch a few small holes in a lid, add the eggs, close the lid, and put the deli cup in a place where the average temperature is as required and the min. and max. are not exceeded. Check the humidity every other day disturbing the eggs as little as possible.
Instead of the paper towels, you can use moist vermiculite.
From a Reader:
For my Box Turtles and water Turtles I place the eggs on moist papertoweling which covers the bottom of a clean pie tin. I cover the eggs with paper toweling and maintain a moist condition throughout the growing period. It is easier for me to allow 12 hour natural drying and then wetting by hand. I can also have easy access to the eggs for observation all the time. When I see any sign of mold, I carefully wipeand rinse the eggs while maintaining UP position of the eggs. My eggs always have clearly defined hemispherical real white on top half and wetter looking white on the bottom half of the egg shells making TOP easy to determine if movement occurs in error. If you over water the eggs can drown!
Paper toweling is clean off the fresh roll.
The basic idea is to fill the bottom of the tank with water, use an aquarium heater to heat the water, put the eggs in a plastic container filled with moist substrate on an island in the tank, cover the tank.
This creates an even temperature (use thermometer to check) at high humidity. You can control the humidity somewhat by how much you cover the tank, but this also affects temperature. Best for eggs that require almost 100% humidity.
5 or 10 gallon aquarium
Glass cover or other other air-proof cover for aquarium
Aquarium heater with thermostat
One or two bricks
Plastic shoebox (with lid) that fits into the aquarium
Bag of Vermiculite (TM)
Put aquarium in a safe and undisturbed place.
Arrange bricks in aqurium to make pedestal for shoebox.
Add water to level of brick tops.
Install aquarium heater into aquarium.
Fill shoe box about halfway with a mixture of 1:10 or Water:Vermiculite; blend well. Err on the dry side, not the wet side. You can always add a bit more water.
Make small holes into the lid of the box.
Put thermometer into shoebox on top of Vermiculite.
Place shoebox on bricks and cover the tank.
Turn on heater.
Adjust aquarium heater until desired temperature in the shoebox is maintained.
Just before hatching:
(Assuming it is summer and the room where the incubator is is at least at room temperature.)
Turn heater off and remove heater and bricks.
Place newspaper at bottom and shoebox on top and a shallow water bowl next to it. Close up setup and wait for the miracle to happen.
Hatchlings can and will crawl out of the shoebox onto the newspaper. Check box every few hours for hatchlings that need help. Once all eggs have hatched, I remove the shoebox, add a hide place and a heating pad (under 1/3 of the tank), and the nursery is complete.
Hints and Tricks:
Check eggs every few days; this also ensures that there is enough air.
* I put the lid on the shoebox slightly propped, so that if there should be water drops, they will collect at one end of the box where I don't put any eggs.
* I use filtered water to moisten the Vermiculite.
* I make a small square whole into the box so I can see the thermometer without opening the lid.
* Note that you must keep the same side up at all times for turtle eggs, or the eggs will die. Snake eggs can be turned.
* Handle eggs as little as possible to keep your germs away from them.
* When removing the lid, be careful not to drip water on the eggs.
* When adjusting the temperature, check during the hottest time of day. It is ok to err on the cool side! Eggs will just take a bit longer to hatch.
* This incubator is also ant-proof! * Instead of a lid on the shoebox, you can use Saran Wrap (TM) and leave a small airgap on one side. That way you can see the eggs. Make sure it is on tightly. If it sags and touches the eggs, water will collect there and the eggs might get hurt.
There are a number of incubators available on the market. I eventually got one because I can set it up in 5 minutes, it’s easy to clean, it’s got rheostatic temperature control, it’s always available, it’s easy to maintain temperature and humidity levels.
I got a styrofoam Hovabator without a fan. (You don’t want a fan for reptile eggs.) You need a thermometer and a humidity gauge with that. I put the eggs in small deli cups with no substrate for hard-shelled gecko eggs and moist vermiculite for all other eggs.
This method has give me the least problems with fungus and the hatch rates are good.
Most important is to make sure you don’t forget to add water regularly. Sometimes, I put an additional container with water right underneath the heating element for additional humidity.
From there, of course, there is no limit to the possible level of sophistication.
"Incubation of Reptile Eggs" by Guenther Kohler has instructions for buidling incubators and on incubation temperatures for reptile eggs. This book is highly