Phasmids

What are phasmids?

Phasmids are herbivorous insects of the order Phasmida that mimic twigs, leaves or bark to go unnoticed. Around 3,000 species are known, divided mainly into three groups: stick insects, leaf insects and bark insects. The body is divided into head, thorax and a segmented abdomen.

Phasmids undergo incomplete metamorphosis (they are hemimetabolous): nymphs hatch from the egg looking similar to adults, but smaller, and grow shed by shed, usually over 5 to 7 sheds. On reaching maturity they become able to reproduce and take on their final colouring. As a pet, a phasmid is calm, silent, harmless and easy to feed, which is why it is one of the most recommended invertebrates for beginners and for educational projects with children.

What is the difference between a stick insect, a leaf insect and a bark insect?

The difference between the three groups of phasmids is what they mimic and, with it, the shape of their body. All three eat the same thing, bramble and rose leaves, and need a terrarium at least 3 times their length in height and 2 in width.

• Stick insect: long, thin body that mimics a twig. For example, Phaenopharos khaoyaiensis reaches 14 cm and Medauroidea extradentata 10 cm. Humidity around 75%.
• Leaf insect: flat, broad body that mimics a green leaf and sways in the breeze. Phyllium philippinicum measures 8 cm as an adult. Humidity 60-75%.
• Bark insect: sturdy body, in brown or greenish tones, with shapes that mimic bark or dry wood. The Sungaya aeta female measures 9 cm and needs 80% humidity.

How do phasmids reproduce?

Phasmids reproduce in two ways: sexually, with a male and a female, or by parthenogenesis, in which the female lays fertile eggs without a male and the offspring are clones of the mother. Many species can do both, and some have only females: for example, Phaenopharos khaoyaiensis and Medauroidea extradentata are parthenogenetic.

Females drop their eggs on the ground, stick them to leaves or flick them away at random. Depending on the species, they lay around 3 or 4 eggs a day, and hatching takes from weeks to months: in Phyllium letiranti, 4 to 5 months. The most curious case is Extatosoma tiaratum: in Australia, Leptomyrmex ants collect the eggs and carry them into the nest, and the nymphs hatch looking like those ants, black with a reddish head, so they can get out without being detected.

What does a phasmid need in captivity?

A phasmid needs a vertical, ventilated terrarium, fresh leaves and humidity suited to its species. The parameters we use in our own breeding are:

• Terrarium: at least 3 times the insect's length in height and 2 times in width, because it hangs down to shed.
• Temperature: they tolerate 18 °C, but ideally keep it above 20 °C, around 25 °C; if it drops lower, use a heat mat.
• Humidity: between 60% and 90% depending on the species, with misting.
• Food: fresh bramble and rose, with the stems in a jar of water in the centre of the terrarium.
• Handling: gently, letting them climb onto your hand and never picking them up by the legs, which they can shed to defend themselves.

Full details are in our phasmid care guide.