Stick Insects

Stick Insects

Introduction

A discussion about stick insects may well bring to mind the walking twigs occasionally seen in the veldt, such as the one in the accompanying picture. If so, you would be correct but may be ignoring some of the most fascinating and bizarre creatures on the planet.

Stick insects and their relatives, the leaf insects, are members of the order Phasmida, the name coming from a Greek word meaning spectre or something unpleasant or menacing, which is a far cry from your walking twig but does give an indication that many species of phasmid occur is fairly hideous shapes and sizes.

Phasmids have representatives in most parts of the world and, when full grown, they range in size from a staggering 55 centimetres in length for the Malaysian Phobaeticus to a modest one centimetre Californian Temima. The order also includes one of the heaviest insects on the planet – a female Heteropteryx can weigh 65 grams, which is a lot for a bug. They may be simple sticks or complex thorny monsters, which is part of the attraction.

Perhaps phasmids are best known for their amazing camouflage and this reputation is well deserved as even their eggs look like the seeds of plants. On hatching the vulnerable youngsters employ a range of defence strategies. Many will use the passive procryptic defence of their parents, in other words they blend into the background. Others, such as the Spiny Stick Insect, take a more dynamic approach and when newly hatched they run at high speeds and resemble the vicious fire ants of the Australian outback. Later they pretend to be scorpions, with their abdomens curled over their back. Some stick insects escape by flying, while others use their brightly coloured wings to startle nosey predators. A few American species sport warning colours and secrete a nasty fluid. Such aggression is rare and Old World phasmids are quite harmless.

Although interest in stick insects in South Africa is still in its early days the Australian Spiny Stick Insect, Extatasoma tiaratum, is becoming well known through pet shops, so this article will provide some basic guidelines on care for this species, as well as some of its relatives.

Care in captivity

Most phasmids are simple to keep and the Spiny Stick Insect is one of the easiest, feeding on a range of different plants such as bramble, fruit trees and roses but eucalyptus, or blue gum is probably the best. Eucalyptus has the advantage that it is the natural food plant in Australia and is not deciduous but seems to be available almost everywhere, despite efforts to clear it. The species of eucalyptus does not matter and the insect is happy enough to switch from one to another; even the florists’ Penny Gum is eaten with relish.

Cages for stick insects can be as simple or as complex as desired. We use flexariums but an old glass or plastic aquarium with a netting lid can be used and even large plastic sweet jars can work if enough ventilation is given. A picture of a simple home made cage is shown. The insects are mainly nocturnal so do not require light and room temperature is quite sufficient. As far as the stick insect is concerned all it needs is food and space to move about.

To keep the food fresh the eucalyptus branches are put in a suitable water bottle and if it is changed every four or five days the insects should thrive. It is a good idea, although not essential, to spray the cage every day and the insects will be seen drinking the droplets. Their droppings are dry, so should not create either smell or mess.

Typically the Spiny will reach maturity in four or five months, subject to conditions, undergoing several skin changes along the way. Even before they mature the sex can be determined as the female has a row of ridges along her back that the male does not. As they grow these differences become more marked until the final instar when the male’s spindly body and wings are obvious. The male can fly but not far; the female, fat and bloated with eggs, is not able to do more than walk slowly. Although some species can live for over three years, female Spinies live for roughly fifteen months from hatching, with the males living a few months less. However, once you have a female laying eggs you will have stick insects for as long as you want.

Breeding the Spiny is simple: if there are a male and female together then mating will occur. Interestingly, even if there is not a male present you will still get fertile eggs, just not so many. A healthy mated female can allegedly lay over 1,000 eggs, which are just dropped onto the ground. Although the eggs mimic seeds they are fairly easy to spot among the droppings as they are shiny and white with brown swirls. Every few days new eggs should be removed and placed in a plastic box lined with paper towel. Every other day the box is lightly sprayed; too much water and the eggs may go mouldy but too little will mean that the nymphs may have difficulty hatching. Keep the eggs at around 25c and in four to six months you may be fortunate enough to have 1,000 nymphs frantically racing around pretending to be fire ants looking for food.

Other species

Other species of stick insect require more or less the same conditions but may eat different food plants. For example, the Malay Tree Nymph, Heteropteryx dilitata, is a long lived monster that feeds on guava; it lays its eggs in soil which may take 12 months to hatch. Eurycantha species can look like a cross between a Parktown prawn and a Spiny but are harmless; they spend the day hidden in leaf litter at the bottom of the cage and feed on oak.

Leaf insects are fascinating creatures to keep and the Javanese leaf insect, Phyllium. Bioculatum is simple to rear on rose plants. The giant Malay leaf insect, Phyllium giganteum, feeds on guava but is more difficult to keep; male Malay leaf insects are rare and most cultures consist only of females.

This is a small sample of the hundreds of species currently being bred around the world and there can be few creatures that can provide as much fascination for so little attention. The Internet is a good source of information on the conditions needed.