Box turtles are omnivores which means they will eat a variety of both animal and plant-based foods. The proportions of animal versus plant-based food items will depend on both the age and the species of box turtle that you are feeding. Generally, hatchlings and juvenile box turtles are more carnivorous than adults, which are typically more herbivorous, and species' diets also vary.
Vegetables and Fruits to Feed to Box Turtles
A wide variety of fruits and vegetables should be offered to your box turtle daily in order to provide a balanced diet. Items should be clean and pesticide free and some people strongly recommend feeding only organic items.
Particular attention should be paid to the calcium and phosphorus balance in the items in the diet to prevent metabolic bone disease. Aim for at least a 1:1 ratio of calcium to phosphorous (up to 2:1), but the importance of this ratio in each individual item is not as important as the overall balance. Feeding a wide variety of items with an emphasis on those items with a good calcium to phosphorus ratio is the best way to maintain a healthy diet. Referring to a table of many different vegetables and fruits with their calcium to phosphorus ratios makes it easy to know what the ratios are of what you are feeding. The items with the calcium greater than 1.0 are those which have a good ratio and should be emphasized in the diet. As an example, bananas (a favorite of many turtles) have a ratio of 0.3:1 (which is low) so this means they should be fed in moderation.
The following list is a variety of fruits and vegetables (listed in no particular order) that have good calcium to phosphorous ratios and are suitable for box turtles to have included in their diets.
- Dark leafy greens such collard greens, mustard greens, parsley, endive/escarole, dandelion greens, beet tops, spinach, and kale (but be aware of the oxalates in the type of greens you are feeding since foods high in oxalates can bind calcium in your box turtle, making feeding them counterproductive)
- Chinese and green cabbage
- Green beans
- Apples (with skin)
- Butternut squash
- Celery (too much can cause diarrhea so be sure to limit the amount you feed)
- Iceberg lettuce (but it is not very nutritionally dense and can cause diarrhea so limit the amount you feed)
Other vegetable and fruits are acceptable to include in the diet but should not make up the bulk of the daily meals.
Insects to Feed to Box Turtles
A variety of fresh and natural prey items are the best types of insects for your box turtle. These insects can be obtained from pet stores and bait shops. If you choose to feed items caught outdoors be very careful about possible exposure to pesticides. Box turtles kept outdoors will probably hunt down wild insects and other invertebrates on their own, too.
- Wax worms
- Super worms
- Red worms
Other animal-based items can include minnows, small chunks of cooked meats such as chicken and beef heart (raw meats offer too much chance of bacterial contamination) and occasionally moistened, high quality, low-fat dog food.
Commercial Diets for Box Turtles
There are commercial box turtle diets available that are marketed as nutritionally complete but you should be wary of formulated reptile diets as a long-term diet. Typically they are only recommended as a supplement to a variety of fresh foods.
Vitamin and Mineral Supplements for Box Turtles
This is a somewhat controversial area and the need for vitamins and supplements depends on the diet and housing (outdoors versus indoors). However, it is probably wise to dust the turtle food with a well-balanced reptile calcium and multivitamin supplement at least a couple of times a week. Turtles kept outdoors under natural sunlight will produce their own vitamin D3 and won't need this vitamin supplemented but calcium is still beneficial in order to prevent metabolic bone disease if you are not providing a well-rounded diet.