Stick insects: from two-centimetre males to the world’s longest insect
Stick insects, the order Phasmatodea, are plant-eating night feeders that hide in plain sight by looking like twigs or leaves. They live on every continent except Antarctica and range from males about 2 centimetres long to a Chinese species whose females stretch up to 64 centimetres, legs included.
Females are usually larger than males. The longest known species, still formally undescribed and nicknamed Phryganistria “chinensis”, is the longest insect on Earth, while the heaviest is probably Heteropteryx dilatata, whose females can weigh around 65 grams. Bodies may be cylindrical like sticks or flattened like leaves, and many species lack wings or have only stubs. Winged forms have a long thorax to hold flight muscles, with narrow hardened forewings over broad hind wings whose vein pattern is unlike any other insect’s.
Their feet carry two kinds of grip. Sticky toe pads help on climbs, while hairy heel pads further up the leg create strong friction under light pressure, so the insect need not tear its foot free at every step. All species have compound eyes that work well in dim light, but simple light-sensing eyes occur in only five groups. The order is most diverse in Southeast Asia and South America, and Borneo alone has more than 300 species.
Stillness and disguise are the first line of defence; some species grow moss-like or lichen-like outgrowths, and a few change colour with their surroundings. If found, others flash hidden bright wings as they drop, curl up like scorpions, jab with spiny hind legs that can draw blood from a human hand, or spray irritating chemicals from glands behind the head.
A female lays between 100 and 1,200 eggs, flicking them to the ground, burying them or gluing them to plants. The eggs of Diapheromera femorata carry fleshy knobs that tempt ants to haul them into their nests. Many species can reproduce without males, producing daughters that are copies of their mothers, and nymphs pass through gradual stages to adulthood without a pupa.
Source: Phasmatodea
