Milwaukee Reptiles - Breeders of Rhacodactylus Geckos and Other Exotic ReptilesMilwaukee Reptiles - Breeders of Rhacodactylus Geckos and Other Exotic Reptiles  

Egg Fertility and Incubation Information

This particular article does not describe incubation methods, mainly because there are many that have been well documented and work well. If you are interested in learning about incubation methods for Leopard Geckos (Bearded Dragons are very similiar as well), please visit one of the following:

Incubation Information:

Candling is the process of holding an egg up a light so that you can see the contents within. When related to reptiles, it is usually used to determine if the egg is indeed fertile.

Making a Candling Device:

You don't need to go and buy a fancy device for candling your eggs. A simple flashlight with some aluminum foil is all you need. Simply poke a hole in the aluminum foil about the width of a standard pen, and then wrap the aluminum foil around the end of the flashlight. When you turn the flashlight on, the only light coming from the flashlight should be from the hole. If you are candling smaller eggs (such as Crested Gecko eggs), the hole should be smaller.
Our Egg Candling Device

Candling the Eggs:
Really simple: Turn on the flashlight and hold the egg up to the hole in the foil. It's easier to see the egg if the rest of the room is dark.

It's also worthwhile to note the line on top of the eggs. When the eggs are found in the animal's cage, we mark a line on the top of the egg to indicate the top. If an egg is rotated during incubation (by you or perhaps a hatchling in the same container), the embryo can be crushed by the pressure or even drown. Therefore, always keep the egg in the same orientation as it was found.

Leoaprd Gecko Eggs in Incubation Container

Bearded Dragon Egg On Top of Candling Device (Side view)

Leoaprd Gecko Egg On Top of Candling Device (Top view)

Determining Fertility:
Fertility can usually be determined after about 3 days of incubation. In some cases, however, it may be more difficult to tell.

Infertile eggs are usually pretty easy to spot, usually indicated by a solid yellowish color with no visible veins. I have had eggs show veins, and then die sometime during incubation, so the indication that an egg is fertile does not necessarily mean that it will hatch. Also, don't throw out infertile eggs until they begin to grow mold or severely dent in! I have had eggs hatch that I thought were infertile. The moral: This method is not 100%! It does not indicate the hatchability of the eggs.

Eggs that are infertile may begin to turn a yellowish-brown color, and may begin denting in or growing mold. Denting, however, can also be caused by a lack of humidity, and mold can be caused by too much, so make sure your humidity is correct before assuming the eggs are bad. The following below should be used as a guide.

Fertile Leopard Gecko Eggs (about one week old):

Notice that the veins are visible in the eggs.

Fertile Leopard Gecko Eggs (about one month old):

Notice that the embryo can be seen growing inside. Right before they are due to hatch, you can sometimes see the stripes of the gecko or the darkness of the eyes.

Fertile Bearded Dragon Eggs (about one month old):

Notice how the embryos are attached to the top of the egg. This is why it's important not to change the orientation of the egg (hence we draw a line on top of the egg).

Infertile Leopard Gecko Eggs:

Notice how the eggs are a solid yellowish color and there is no sign of anything beginning to grow inside.

Hopefully, if all went well, you'll end up with some cute little hatchlings in no time!

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