In everyday speech, a bug is any small creepy-crawly. Entomologists use the word far more narrowly. Only one group of insects earns the name true bugs, and it includes stink bugs, assassin bugs, water striders and bed bugs. Plant bugs and squash bugs belong too. According to the University of Florida, the separate word bug is reserved for insects in this group, while look-alikes such as sowbugs and mealybugs are written as one word because they belong elsewhere.
What are true bugs?
True bugs are insects with piercing and sucking mouthparts. The University of Florida describes a jointed beak that arises from the front of the head, and the Smithsonian describes hypodermic-needle-like mouthparts that let them draw fluids from plants and animals, including humans. They also share a distinctive wing design:
- Two pairs of wings: the front pair is leathery at the base and membranous at the tip, and it lies flat on the back at rest
- Incomplete metamorphosis: young bugs resemble adults but lack wings, and there is no pupal stage
- Exceptions: some species are wingless or short-winged, and lacebugs have lace-like front wings
How do true bugs feed?
A true bug feeds by piercing tissue with its beak and drawing up fluid. Plant feeders take sap. Predators such as assassin bugs take the body fluids of insect prey like caterpillars and cockroaches. A few species feed on the blood of animals, including humans. One basic tool, a needle-like beak, has been adapted to very different diets across the group.
Hemiptera vs. Heteroptera: why two names?
Sources do not always use the same label. The Smithsonian uses Heteroptera for true bugs, while the University of Florida uses Hemiptera and notes a close relationship with a group called Homoptera, whose beak arises farther back on the head and whose wings are usually held roof-like. Classification has changed over time and references draw the boundaries differently, so it helps to check which name a source uses before comparing numbers. In every case the insects described have the same leathery-based front wings and sucking beak.
How many species of true bugs are there?
The Smithsonian cites approximately 40,000 described species worldwide and over 3,800 in the United States. That makes true bugs a large contributor to insect biodiversity. Because only described species are counted, the real number is probably higher, though no source consulted here gives an estimate.
Types of true bugs
- Stink bugs: release a foul-smelling chemical that deters predators
- Assassin bugs: prey on insects such as caterpillars and cockroaches
- Water boatmen and water striders: live on or in water and also hunt insects
- Water scorpions: aquatic bugs found in ponds
- Bed bugs and their relatives: feed on blood, and some relatives live in bat and bird nests
- Plant bugs, squash bugs and lacebugs: feed on plants
- Common milkweed bug: a familiar example named by the Smithsonian
Where do true bugs live?
True bugs occupy an unusual range of places. Many are aquatic, living on the water surface or in ponds, including low-oxygen polluted water that would stress other animals. Others live on plants or in the nests of bats and birds. Each of these habitats supports its own set of species, which is one reason the group is so varied.
What roles do true bugs play in ecosystems?
True bugs are both feeders and food within an ecosystem. Assassin bugs, water boatmen and water striders hunt other insects, so they help limit those populations. Plant-feeding species suck sap, and the damage is usually minor unless their numbers become very large, according to the Smithsonian. Chemical defenses like those of stink bugs show how strongly predators shape their lives.
Are true bugs pests?
The sources emphasize different sides of the answer. The Smithsonian says most true bugs are not pests and that only a few are pests or disease carriers. The University of Florida notes that many are significant plant pests, while some are beneficial predators of other insects. Both can be true at once, because the group is so large and varied.
The clearest health concern is Chagas disease. The Smithsonian notes that conenose bugs, a group of tropical assassin bugs, transmit it, and that it can be fatal. Anyone concerned about an infestation or exposure should consult local public health or pest control authorities. On a lighter note, some true bugs are eaten by humans and pets, and certain water bugs are used for flavoring in Chinese food.
True bugs vs. other insects
All true bugs are insects, but most insects are not true bugs. Beetles, butterflies, flies and ants all belong to other orders. A simple field check is to look at the wings and mouthparts: a front wing that is leathery at the base and lies flat over the back, combined with a sucking beak, points to a true bug. The range of these features reflects long evolution of feeding strategies, from sap sucking to predation.
Frequently asked questions
Why are they called true bugs?
Entomologists use bug for one group of insects only. Calling them true bugs separates them from the many other insects that people call bugs in everyday speech.
Do true bugs bite?
Some can pierce skin with their beak, and some feed on blood, including bed bugs and conenose bugs. Most species feed on plants or other insects.
Why do stink bugs smell?
They release a foul-smelling chemical that deters predators.
Are true bugs aquatic?
Many are. Water striders live on the surface, water boatmen and water scorpions live in ponds, and some tolerate low-oxygen polluted water.
How do young true bugs differ from adults?
They resemble adults but lack wings. There is no pupal stage, so the young grow into adults through gradual change, which is called incomplete metamorphosis.