If the box turtle is outside, try feeding it during late morning hours or after a light sprinkling of water. If it is early in the year or late in the fall, you may need to adjust the time of feeding to a later hour so the turtle has a chance to warm up first. When nighttime temperatures go below 65° F the turtle will need to warm up its body temperature before it will feed. Cold turtles cannot digest their food properly.
Some turtles are very timid and will not eat in the open. You need to provide an eating area where it feels safe, for example, near a shrub or under a hide box. Is the food in the sun or shade? Try putting the food plate in an area where it is partly shaded in the summer. A turtle can overheat very quickly, and it may not venture out into the sun to eat if it is too hot.
Wild turtles are omnivores and in will eat earthworms, snails, grubs, beetles, caterpillars, carrion, grasses, fallen fruit, berries, mushrooms and flowers. They will take a bite of anything that smells edible. You must feed your turtle what it needs to eat, not what is convenient for you to give it. If you find something your turtle really loves, then you are half way to retraining any bad eating habits. If it loves earthworms then try giving it chopped worms with grated yellow squash and cantaloupe.
If your turtle is kept indoors, and this is recommended only for hatchlings and sick or weak box turtles, then you have other factors to consider if your turtle won’t eat. There should be a gradient of temperatures in the housing with the warm end being around 85-87° F and a cool area around 75-78°. This cool area could be where the hide box or burrowing area is placed. Feed the turtle at the same hour and place each time. A UVA and UVB producing fluorescent lights can make foods more appealing to turtles by bring out the colors. It may also stimulate appetite in much the same way a nice bright sunny day makes us happy. Full-spectrum light is also necessary for vitamin D3 production, especially if your turtles is not getting vitamin D3 from food and is not living outside.
After you have eliminated all physical causes of a hunger strike and the turtle still does not eat, then you will have to look at medical reasons. For a beginning turtle keeper it may be hard to tell from just behavior if a turtle isn’t eating due to an illness. If the feces look firm and no whitish mass of worms is seen, you can try soaking the turtle in slightly warm water that contains a few drops of reptile vitamins for half an hour each day for one week. The water should only go half way up the back of the shell and not over the turtle’s head. If a turtle still hasn’t eaten after a week, then a trip to a reptile veterinarian may be necessary.
If the eyes are closed and puffy, the box turtle will not eat and should be taken to a veterinarian. There are several reasons why the eye condition may be present. Vitamin A deficiency causes the glands in the eye to dry out and infection may begin. Upper respiratory illnesses can also cause the eyes to become infected. These conditions are best handled by a vet who may want to treat it with antibiotics.
A well-balanced diet is easily provided from a combination of common grocery store items and backyard biota. Following is a list of foods to give your box turtle. Most foods are acceptable if given in moderation. Each feeding should include a food item from several food groups. For example, include a protein, a vegetable and a fruit, or a protein, a fruit and a green leafy vegetable. By varying the kinds of food you give your turtles, you are increasing the chances that they will get the mineral and vitamins necessary for good health. You also lessen the chances of them fixating on just a few foods, plus it is naturally for box turtles to have a varied diet.
Feed young turtles a small amount of food every other day. Adults can be fed every 2or 3 days in late spring and summer. Regardless of the age of your box turtle, a feeding schedule should be made in advance. During the summer months when trying to strengthen and add weight to the box turtles, the schedule may be like this: Monday, Wednesday and Saturday are full meal days. Other days, feed a small snack where they might get a beloved treat like bananas or tomatoes sprinkled with vitamins. On Sundays the turtles receive no food. A day of fasting will not harm a healthy turtle. Of course, use your own best judgment. You may want to feed more or less often depending on the health or activity level of your turtle. However, clean water should be provided daily.
For more on different types of food check out this site... http://www.boxturtlesite.info/diet.html