Do I Pester You? Some insects are considered beneficial. Beneficial insects are helpful to humans, animals, and plants. A beneficial insect may assist in pollinating flowers or eating harmful organisms. On the other hand, some insects are pests. Insect pests may eat plants or act as parasites to humans or animals. Determining whether insects are beneficial or pests often is based on what the insects eat. For the insects below, try to decide whether they are beneficial or pests based on their given diet. Aphid - a small insect that drinks plant juices Beneficial! A Pest! Grasshopper - an insect that eats vegetation Beneficial! A Pest! Praying Mantis - an insect that preys on a variety of insects, especially flies Beneficial! A Pest! Mosquito (female) - an insect that drinks blood Beneficial! A Pest! Ladybug - an insect that eats aphids Beneficial! A Pest! Honeybee - a bee that pollinates flowers Beneficial! A Pest! Carpenter Bee - a bee that bores holes in wood (commonly fences) Beneficial! A Pest! Hornworm Caterpillar - an insect that eats tomato plants Beneficial! A Pest! Cicada - a large, winged insect that drinks plant juices Beneficial! A Pest! Cicada Killer - an wasp-like insect that feeds its larvae cicadas Beneficial! A Pest!