What Not to Feed Three Toed Box Turtle
What do box turtles eat?
Box turtles are omnivorous, meaning that they eat both plant- and animal-based foods. Some box turtles, like the ornate box turtle, eat insects. They have a sharp eye and keen sense of smell. Young, growing box turtles, up to 4-6 years of age, tend to be primarily carnivores, while adults tend to be herbivorous (eat only plant matter).
As a guideline, your box turtle's diet should be about 50% plant-based material and 50% animal-based material. Different breeds of box turtles have slightly different nutritional needs. There are many different opinions regarding exactly what box turtles should eat in order to have a nutritionally balanced diet; speak to a veterinarian familiar with box turtles to determine specifically what to feed your box turtle.
How often should I feed my box turtle?
Most young turtles eat daily, while older turtles can be fed daily or every other day, depending upon the pet's individual appetite, body weight, and overall health.
What types of plants I can feed my turtle?
Most (80-90%) of the plant material fed to box turtles should be vegetables and flowers, and only 10-20% should be fruit. As a rule, dark, leafy greens should make up the largest part of the diet. Yellow, red, and orange vegetables can also be included. Avoid light green vegetables, including iceberg or head lettuce and celery, as they are composed mainly of fiber and water with few nutrients. The inner, light-colored parts of some vegetables are less nutritious than the darker green outer leaves, so they should not be offered.
Acceptable vegetables that should represent a high percentage of the box turtle's diet include collard greens, beet greens, mustard greens, broccoli, turnip greens, alfalfa hay, bok choy, kale, parsley, Swiss chard, watercress, clover, red or green cabbage, savory, cilantro, kohlrabi, bell peppers, green beans, escarole, and dandelion. A lesser percentage of the diet can include cactus, various squash, sprouts, cooked sweet potato, parsnips, okra, cucumber, asparagus, mushrooms, carrots, peas, and corn. Swiss chard, spinach, and beet greens should be fed sparingly, as they contain oxalates that can bind to calcium and other trace minerals, preventing these nutrients' absorption in the turtle's intestine. Diets composed primarily of these vegetables can ultimately lead to nutrient deficiencies. Caution should also be exercised when feeding cabbage, kale, or mustard greens in excess, as these vegetables contain goitrogens; excessive consumption of these items may lead to hypothyroidism.
Fruit should be fed more sparingly than vegetables, since they are often preferred by box turtles over vegetables and tend to be less nutritious. Fruits to offer include apples, pears, bananas (with skin), mango, grapes, star fruit, raisins, peaches, tomato, guava, kiwis, and melons. Fruits that are particularly healthy include figs (which are high in calcium), apricots, dates, raspberries, and strawberries. As a treat, flowers such as geraniums, carnations, dandelions, hibiscus, nasturtiums, and roses may also be offered.
"Fruit should be fed more sparingly than vegetables, since they are often preferred by box turtles over vegetables and tend to be less nutritious."
Vegetables and fruit can be offered cooked or raw, although raw tends to be more nutritious, as cooking can destroy many nutrients. Thoroughly wash all fruits and vegetables before feeding them. Flowers can be home-grown or purchased from floral shops. Often, floral shops throw out older, wilting flowers. While these may be unacceptable for sale to the public, some store owners are willing to offer them at reduced cost for pet food. Be sure that no chemicals have been applied to the flowers or water before offering them to your turtle.
Food should be presented to box turtles in a shallow, clean dish that is not easily flipped over. Vegetables should be finely chopped and mixed together to discourage the turtle from eating only preferred food items.
What animal-based protein foods I can offer my turtle? 
Depending on the age, breed, and health status of your box turtle, your veterinarian may or may not recommend feeding animal-based protein sources. When offered, some appropriate animal-based protein sources include grasshoppers, crickets, mealworms, wax worms, silkworms, moths, slugs, earthworms, and hard-boiled eggs. Commercially available reptile pellets provide an excellent protein source. Live prey, such as crickets and various worms, should either be raised inside by the owner or purchased from a pet store, bait store, or reptile breeder. Collecting insects from outside to feed pet turtles is generally not recommended, as fertilizers and insecticides on insects can be toxic to turtles.
The key is to feed a wide variety of healthy items, including both plant- and animal-based protein sources, to provide your box turtle with balanced nutrition.
Do I need to give my box turtle vitamins and minerals?
Like most reptiles, turtles require more dietary calcium than phosphorus. Most veterinarians recommend lightly sprinkling the vegetable matter offered to the box turtle with a calcium powder (calcium gluconate, lactate, or carbonate) 2-3 times per week. In addition, a light sprinkling of a multivitamin-vitamin mineral powder made for reptiles is also recommended weekly, especially if it contains vitamin D3 which can be toxic to turtles if over-supplemented. The best way to ensure reptiles are consuming the supplements is to dust them onto small portions of their vegetables, and feed those dusted portions first.
"Turtles require more dietary calcium than phosphorus."
A common problem seen in pet box turtles is over-supplementation with vitamins (especially vitamin D3) and minerals. Check with your veterinarian about the need to supplement your pet's diet with any kind of vitamin or mineral.
What are box turtles' water requirements?
Fresh clean water should be available to box turtles at all times. Box turtles not only drink from the water bowl but will also bathe in it. Provide water in a shallow dish, crock, or pan that cannot be easily tipped over, and ensure the dish has some sort of a "ramp" (such as a rock, log, or commercially available turtle ramp) that allows the box turtle to easily climb in and out for soaking and drinking. The water level should reach up to its chin when its head comes out of its shell. Change the water daily, and clean the water bowl frequently, as many box turtles will defecate or eliminate in their water bowls.
You can mist your turtle with a water sprayer, too, a few times a week as well to help keep it hydrated.
Since all turtles can carry Salmonella bacteria that is transmittable to people, always wash your hands thoroughly after feeding, cleaning, or handling turtles.
Source: https://vcahospitals.com/know-your-pet/turtles-box-feeding#:~:text=Avoid%20light%20green%20vegetables%2C%20including,they%20should%20not%20be%20offered.