Stick & Leaf Insects of Peninsular Malaysia & Singapore

Stick insects is the popular name given to the usually relatively long, thin insects resembling twigs or sticks, belonging to the insect order Phasmida (also known as Phasmatodea, Phasmatoptera, Cheleutoptera and others). Leaf insects also belong to the same order and, as implied, their bodies are flattened to resemble leaves. Approximately 2,500 species of Phasmida have been described throughout the world, where they are commonest in tropical and subtropical countries. They are often called phasmids i.e. based on Phasmida, an appropriate name as it originates from the Latin word Phasma, meaning spectre, ghost, apparition or phantom. 103 species and I subspecies are recorded in this book as valid. Species range in length from the tiny Timema species from the USA and Mexico (under 12mm) to the giant Phobaeticus kirbyi from Borneo (328 mm, nearly 13 inches), originally misidentified as Phobaeticus serratipes, a closely related species. P. serratipes is the longest species included in this book, at 278 mm, over 11 inches. This is simply the length from the head to the tip of the abdomen, as its overall length, including outstretched fore-legs is 555 mm (compared with 546 mm. in P. kirbyi). Whilst mainly green or brown in colour, for camouflage purposes, many species have beautifully coloured wings and Peninsular Malaysian species include some of the more spectacular examples known. Colour and other variation within species can be extreme, but has rarely been discussed in the literature. Certain species possess wings and can fly quite well, more usually the males. Many stick insects have spines of varying length, which may be used to defend them against predators in some species, including birds, animals, spiders and mantids. Various creatures are parasites of phasmids, including flies, wasps, mites and nematode worms. Brief details on the types of defence mechanisms of phasmids are as follows: Procrypsis – The ability to blend in with the background, which aids their concealment from predators. Escape – Many phasmids drop to the ground when disturbed and lie motionless. They often have differently coloured undersides, which aids the camouflage – try finding a phasmid which has dropped down amongst other vegetation. Other species try to walk rapidly away, possibly adopting a ‘rocking’ motion by swaying their bodies from side to side. Winged species will fly and when settled again have invariably ‘vanished’ due to effective camouflage. Displays – Some species make a rustling sound with their wings and/or strike their spined legs together in apparent attack mode. Perhaps the most effective display is a startle display where winged species e.g. Tagesoidea nigrofasciata, open their brightly coloured fan-like wings in the hope of startling a predator. The wings may be kept open for several minutes. Defensive secretions from the mouthparts or prothoracic glands are also often used in combination with the above reactions, although little is known about these secretions. Hundreds of scientific papers have been published on a single species, Carausius morosus, known as the Laboratory or Indian Stick-insect, one of the few species to be extensively studied. However, little is known about its distribution or habits in its native India, but it is a typical phasmid, breeding in captivity by parthenogenesis, discussed on page 2. Phasmids of most countries have been relatively poorly studied. It is only in recent years that more detailed studies have been made on the stick insects of various regions, with books published on species from Europe (Brock, 1991), New Zealand (Salmon, 1991) and Singapore (Seow-Choen, 1997).