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Phasmids - Leaf and Stick Insects

There are more than 2,500 species of leaf and stick insects, of which some half dozen species are regularly encountered in captivity.

Glasgow Zoopark has maintained several species at one time or another, including the Indian Stick Insect, Macleays Spectre, Pink Winged Stick, and Thailand Stick

As their name suggests, most species camouflage themselves as twigs or leaves, with colouring varying from browns to greens. Many are able to vary their colouration to suit their surroundings should this change. Some - usually the males - are able to fly. The wings are quite attractively patterned. Large varieties of stick insects are impressive with body lengths exceeding 15 cms.

Flight is sometimes used to aid escape. Some species drop to the ground and feign death. Others emit an offensive odour or chemical, whilst others possess spines, or a sharp hooked claw. Allgrowing insects shed; or moult, their skins. From hatching to maturity most shed about five times. If a leg is lost, a new, usually slightly inferior one will regenerate.

Phasmids are interesting to keep in captivity. The Common, or Indian Stick Insect prefers a dry atmosphere, and will live happily in a cage consisting of a wooden framework covered with fine mesh. Other species prefer a more humid atmosphere, so a tank with a peat base is more suitable. The tank should at least be large enough for the insect to hang suspended from a branch whilst shedding.

If the insects have a food plant to hang onto whilst you clean the tank, or glass, then they usually remain in position and don't move around. Catching adults and/or juvenils repeatedly leads to accidents, escapes and injuries.

Most species will eat several species of fairly accessible plants, and trial and error will confirm these for your own particular insects. Privet is the food for the Indian Stick, fresh, young Bramble for the Macleay's Spectre. Try and ensure you know where supplies (in sheltered pockets, will keep growing through the winter!)

Provided the room is kept at an average temperature in the mid- 60 degrees farenheit, no extra heating is necessary, though some species live and breed more successfully at higher temperatures. Most are happy anywhere between 65-80 degrees farenheit. If the temperature falls dramatically at night a 40 watt heat lamp is recommended.

Some species are parthenogenic - females produce fertile eggs without having mated with a male i.e. the Pink Winged Stick. Others mate in the normal manner. If the eggs are left in the cage, the babies hatch after 2-3 months and easily escape through cracks, or drown in the water used in the container keeping the food plants alive, so the necks should be neatly plugged with cotton wool.

If you remove the eggs, remember to label and date them accurately, to help you accurately anticipate likely hatching times.

Looking After Stick Insects

  1. Bottom of cage: Line with newspaper. Do NOT clean out, as eggs lie there, which will in due time hatch.

  2. Twigs of privet: Stand in water. Water jar to be blocked around twigs with paper or a rag, so that nymphs (young stick insects) cannot drown. In water, the privet twigs remain fresh for quite a long time.

  3. Watch out for round gnaw marks, which means they are feeding.

  4. Indian stickies die at about 15 months of age, so do NOT distress yourselves at the sight of the occasional dead body. Twigs of privet MUST stand upright in a cage higher than bottom area.

Indian Stick Insects

It almost goes without saying that these creatures should have freshly picked privet available at all times. Preferably, this should be renewed one a daily basis. In reality, one suspects that the majority of pet owners, after a few months, grow a little tired of what can seem a tedious routine. ‘Replenishment’ becomes an every two or three day routine, or whenever the leaves have wilted or been eaten. From our own observations, one increasingly gains the impression that this restricts egg production, rather as one witnesses in some other arid area animals in response to harsh conditions. We also increasingly feel that if you do not ‘harvest’ the excess offspring, that the consequent overcrowding also reduces reproductive success and survival of the very young stages. Of course, maximising the production of Indian sticks is often the last thing most people want to do, usually it’s the reverse.

However, during 1999 we have given away several hundred young sticks to schools and individuals from a cage measuring no more than 30 cms square. When the young are removed on a gradual, but regular, basis and the adults kept copiously supplied with fresh privet it is just amazing how fast they increase in numbers again.

Despite the fact that many young people and quite a few adults have kept these creatures, one wonders how closely people actually observe or watch them. The written accounts in books and journals do not begin to suggest just how interesting the behaviour of Indian stick insects can be.

Most people are given the impression that their lives consist of avoiding predation by looking like sticks, and obviously this is important. However, stick insects are ‘adventurous’ and relatively fast moving! If they think they have been ‘spotted’ they will take - especially the sub-adults - active avoiding action. They will ‘hide’ on the opposite side of a branch or twig to the perceived danger. If a strong light (like lighting for a photograph or filming) is shone on them, they will all move to the underside of leaves, or at least into shadow. Finally, all stick insects, except for very large adults, will exhibit mimicry if they feel threatened, curling their tail over their backs ‘scorpion-style’.

In the West of Scotland at any rate, if not elsewhere, many first-time owners seem to have the totally erroneous impression that these creatures can eat either brambles or privet. We find that if people appear here, having kept Indian stick insects before ‘but they died’, nine times out of ten, it is because they tried to feed them on bramble!! It cannot be emphasised too strongly that they only eat privet, which brings us onto another point.

Privet is a poisonous shrub, packed with tannins. Could the scorpion-like behaviour of the younger individuals be a ‘double safety’ designed to deter birds and other predators before the toxic residues in their bodies have had a chance to accumulate fully? The large, old adults must be extremely unpalatable, if not dangerous, to most small predators.

Finally, how many owners have witnessed a stick insect shedding its skin? If not, why not? If they are on every pupil’s shelf in his or her bedroom, one would have thought the opportunities for close observation would have been maximised. The process can been speedy, taking only about ten minutes. The insect hangs from a twig. Once out it eats its skin, then the legs, appearing to suck them in from where they were attached to the body, as if eating a stick of rock. After completing the eating of the skin the stick insect then walks to an open area - usually the glass of its tank - to sit, immobile, for several house whilst its new skin hardens, after which the serious business of eating privet leaves starts all over again. Eating the old skin, thus, ‘buys it time’ to rest and harden its skin.