What Is the Biggest Insect in the World?

The insect world is home to some truly remarkable giants. While most insects are small enough to sit on a fingertip, a select few have evolved to extraordinary dimensions that challenge our expectations. From beetles heavier than a mouse to stick insects longer than a human forearm, the diversity of giant insects is genuinely astonishing.

The Heaviest Insect: The Goliath Beetle

The Goliath beetle (Goliathus goliatus) of tropical Africa holds the record as the heaviest insect on the planet. Adult males can weigh up to 100 grams in their larval stage and around 50–60 grams as adults, roughly the weight of a small bird. These magnificent creatures can reach lengths of 11 centimetres and are found in the tropical forests of central Africa, where they feed on tree sap and fruit.

The Longest Insect: Phryganistria chinensis

In 2016, researchers at the Insect Museum of West China discovered a stick insect measuring an incredible 62.4 centimetres in total length. Named Phryganistria chinensis, this species from the mountains of Guangxi province in southern China broke the previous record held by Phobaeticus chani from Borneo, which measured 56.7 centimetres. These extraordinary insects rely on their extreme length and twig-like appearance to avoid predation through camouflage.

Comparing the Giants

The Largest Wingspan: The Atlas Moth

The Atlas moth (Attacus atlas) of Southeast Asia boasts the largest wing surface area of any insect, with a total wingspan of up to 30 centimetres. The tips of its forewings are curved and patterned to resemble snake heads, a defensive adaptation that startles potential predators. Remarkably, adult Atlas moths have no functional mouthparts and do not eat at all during their brief adult life of one to two weeks.

The Giant Weta: A Living Fossil

New Zealand's giant weta (Deinacrida heteracantha) is one of the heaviest insects in the world when measured as an adult. A captive female was recorded at 71 grams, heavier than a house sparrow. These cricket-like insects have existed for around 190 million years, predating the dinosaurs. They survive primarily on offshore islands where introduced mammalian predators have been eradicated.

Did you know? During the Carboniferous period, around 300 million years ago, insects grew far larger than they do today. The dragonfly-like Meganeura had a wingspan of approximately 70 centimetres. Higher atmospheric oxygen levels at the time allowed their tracheal breathing system to support much larger body sizes.

What Limits Insect Size?

Insects breathe through a network of tiny tubes called tracheae, which deliver oxygen directly to their tissues. This system works efficiently for small bodies but becomes less effective as size increases, because oxygen must diffuse passively over longer distances. The concentration of oxygen in the atmosphere is therefore a primary constraint on insect body size.

Other limiting factors include:

• The exoskeleton: As insects grow larger, their exoskeleton must become proportionally thicker and heavier, eventually becoming too cumbersome.
• Gravity: Larger insects face greater gravitational challenges, particularly for flight.
• Moulting risks: Larger insects are more vulnerable during the moulting process, when the old exoskeleton is shed.
• Predation: Very large insects are conspicuous targets for birds and other predators.

Notable Mentions

Hercules Beetle

The Hercules beetle (Dynastes hercules) of Central and South America is the longest beetle in the world, reaching up to 17 centimetres including its enormous horn. Males use these horns in combat over mates, grappling with rivals and attempting to flip them off branches.

Queen Alexandra's Birdwing

Queen Alexandra's birdwing (Ornithoptera alexandrae) is the largest butterfly in the world, with females reaching wingspans of up to 31 centimetres. Found only in the rainforests of Papua New Guinea, this species is critically endangered due to habitat loss from palm oil plantations and logging.