Nevermind just found it I had to add the following code to my mod:
EntityRegistry.addSpawn(entityClass, 2, 0, 1, EnumCreatureType.monster, BiomeGenBase.sky);
So it would look like this:
public static void createEntity(Class entityClass, String entityName, int solidColor, int spotColor) {
int randomId = EntityRegistry.findGlobalUniqueEntityId();
EntityRegistry.registerGlobalEntityID(entityClass, entityName, randomId);
EntityRegistry.registerModEntity(entityClass, entityName, randomId, Eac.mobInstance, 64, 1, true);
EntityRegistry.addSpawn(entityClass, 2, 0, 1, EnumCreatureType.monster, BiomeGenBase.sky);
createEgg(randomId, solidColor, spotColor);
}