Flies, a vast and diverse group of insects, inhabit nearly every corner of the globe, with over 150,000 known species. Their dietary needs vary considerably across species. Understanding what these insects consume is important for observation in natural habitats or maintenance in controlled settings.
Natural Diets of Common Flies
Common fly species exhibit diverse feeding habits in their natural environments. House flies are generalist feeders, consuming a wide array of decaying organic materials. They are attracted to substances like overripe fruits, vegetables, animal feces, and sugary liquids. House flies possess sponging mouthparts, meaning they cannot chew solid food. Instead, they liquefy solids by regurgitating saliva, then soak up the resulting liquid with their proboscis.
Fruit flies, particularly Drosophila melanogaster, primarily feed on fermenting fruits and other sugary liquids. They are drawn to yeast on decaying plant matter, found on overripe produce, sap flows, and alcoholic beverages. Their larvae consume the yeast and surrounding tissues of these decaying materials where they are laid.
Blow flies, recognized by their metallic appearance, are significant scavengers. Adult blow flies consume materials including nectar and plant sap. Their larvae, known as maggots, primarily feed on decaying organic material like carrion, feces, and decomposing garbage.
Flies have specialized sponging mouthparts adapted for liquid feeding. This proboscis allows them to absorb fluids directly or after dissolving solid food with saliva. These adaptations enable them to efficiently process the liquid or liquefied components of their natural diets.
Preparing Food for Captive Flies
For captive flies, providing appropriate nutrition is straightforward, focusing on easily accessible and safe liquid food sources. Sugar water is a common and effective food source for many adult flies, prepared by dissolving sugar in water. Honey diluted with water is another suitable option.
Ripe fruits like bananas, apples, or peaches serve as good food for fruit flies and can also attract house flies. For fruit flies, overripe fruit encourages fermentation, which they prefer. For culturing fruit flies, specific mixtures can be prepared. A typical recipe might include cornmeal, molasses, and agar mixed with water and boiled to create a solid medium. Other mixtures sometimes include potato flakes, nutritional yeast, spirulina powder, cinnamon, or vinegar for a comprehensive diet.
When presenting food, place it in a shallow dish or on a cotton ball to prevent flies from drowning. For fruit flies, a small piece of fruit can be placed directly in their culture vial. Regular misting of the enclosure provides essential hydration, as flies require access to water. Feeding should occur every 2-3 days, ensuring a continuous supply of fresh food and preventing mold or bacteria buildup.
Foods to Avoid
Certain substances are unsuitable or detrimental for captive flies. Solid foods that cannot be liquefied by salivary enzymes should be avoided, as flies with sponging mouthparts cannot consume them. This includes most unprocessed solid human foods.
Substances containing artificial preservatives, chemicals, or cleaning agents are harmful, as these can be toxic to the flies. Highly acidic foods or those with unnatural compositions may not provide adequate nutrition or could cause harm.
Although flies are attracted to decaying matter in nature, providing contaminated or unsanitary substances can introduce harmful bacteria or mold. Ensure food sources are clean and free from pesticides or other environmental contaminants.