Insects, which are a type of arthropod, are easily the most numerous group of organisms on the planet, with about a million species identified so far. The title of heaviest insect in the world has many rivals, the most frequently crowned of which is the larval stage of the goliath beetle, Goliathus goliatus, the top size of which is at least 115 g (4.1 oz) and 11.5 cm (4.5 in). The largest confirmed weight of an adult insect is 71 g (2.5 oz) for a giant weta, Deinacrida heteracantha, although it is likely one of the elephant beetles, Megasoma elephas and Megasoma actaeon, or goliath beetles, both of which can commonly exceed 50 g (1.75 oz) and 10 cm (4 in), can reach a higher weight.
The longest insects are the stick insects, see below.
The beetles are the largest order of organisms on earth, with about 350,000 species so far identified. The most massive species are the Goliathus, Megasoma, and Titanus beetles already mentioned. The longest species is the Hercules beetle, Dynastes hercules, with a maximum overall length of at least 17 cm (7 in) including the very long pronotal horn.
The largest species of this huge order is Gauromydas heros, which can reach a length of 6 cm (2½ in) and a wingspan of 10 cm (4 in). The largest species of crane fly, Holorusia brobdignagius, can attain nearly the same wingspan, but if the legs are extended in front of and behind the body, then an overall length of 23 cm (9 in) makes it the longest true fly.
The largest mayflies are members of the genus Proboscidoplocia from Madagascar. These insects can reach a length of 5 cm (2 in).
True bugs (Hemiptera)
The largest species of this diverse, huge order is a giant water bug, Lethocerus maximus. This species can attain a length of 11.6 cm (4.6 in), although it is more slender and less heavy than most other insects of this size (principally the huge beetles).
Ants and allies (Hymenoptera)
The largest of the ants, and the heaviest species of the order, are the females of Dorylus helvolus, reaching a length of 5 cm (2 in). The ant that averages the largest for the mean size of the whole colony is Dinoponera gigantea, averaging up to 3.3 cm (1¼ in). The largest of the bee species, also in the order Hymenoptera, is Megachile pluto, the females of which can be 3.8 cm (1½ in) long, with a 6.3-cm (2.5-in) wingspan. The largest wasp is probably the so-called tarantula hawk species Pepsis pulszkyi, at up to 6.8 cm (2.7 in) long and 11.6 cm (4½ in) wingspan, although many other Pepsis species approach a similar size.
The largest of the termites is the African species Macrotermes bellicosus. The queen of this species can attain a length of 10.6 cm (4.2 in) and breadth of 5.5 cm (2.3 in); other adults, though, are about a third of the size.
The largest species is probably either the Queen Alexandra's birdwing, Ornithoptera alexandrae, a butterfly, or the Atlas moth, Attacus atlas. Both of these species can exceed a length of 8 cm (3¼ in), a wingspan of 28 cm (11 in) and a weight of 12 g. Their larvae can weigh up to 58 g (2.0 oz) or 1.9 oz (54 g) . However, the white witch, Thysania agrippina, has the longest recorded wingspan of the order, and indeed of any living insect, at up to 30 cm (12 in), though it is exceeded in surface area and mass by both Ornithoptera and Attacus.
Praying mantises (Mantodea)
The largest species of this order is the African mantis. The females of this species can attain a length of up to 12 in. Reports of scientists discovering an unidentified species of mantis in southern China in the 1920s of 18 inches (45 cm.) are unconfirmed. Some larger species have been known to capture and consume frogs, lizards, mice, small birds, and even snakes.
The largest of this widespread, varied complex of insects is the giant weta, Deinacrida heteracantha, of New Zealand. This formidable insect can weigh over 75 g (2.6 oz) and measure up to nearly 10 cm (4 in), rivaling the huge beetles in size.
Stick insects (Phasmatodea)
The longest known stick insect is Phobaeticus chani, with one specimen held in the Natural History Museum in London measuring 567 mm (22.3 in) in total length. This measurement is, however, with the front legs fully extended. The body alone still measures 357 mm (14.1 in). The species with the second-longest body is Phobaeticus kirbyi, which measures up to 328 mm (12.9 in), while the overall length (from the hind to the front legs) is up to 546 mm (21.5 in), and the body weight is up to 72 g (2.5 oz). The second-longest insect in terms of total length is Phobaeticus serratipes, measuring up to 555 mm (21.9 in).