Which of the following best describes external feeders?

The choice that best describes external feeders is the one that highlights their feeding behavior related to food products such as flour and cereal. External feeders are organisms that consume food items from the surface rather than burrowing into them. This type of feeding is characterized by targeting products that are rich in carbohydrates, like grains and processed foods.

The focus on food products like flour and cereal indicates a specific dietary preference that aligns with external feeding habits. These pests are known for infesting stored food products and can cause significant damage to these items, making the correct choice particularly relevant for understanding pest control related to food safety.

Other options refer to different feeding behaviors or dietary focuses. For example, feeding on starches in grains may overlap with external feeding, but it doesn't provide the full context that external feeders are typically associated with processed food products. Consuming wood fibers primarily refers to wood-destroying pests, while only consuming decaying plant matter hints at detritivorous organisms, which are quite different from external feeders that target flour and similar products. This distinction is essential for pest management professionals to identify and address infestations effectively.