The Nursery Team - Talk stick insects

Finding Phasmids 

Every now and then on the nursery we find a stick insect.  Most of us first encounter these at school, kept in aquarium tanks and fed on leaves.  Some of us were lucky enough to take the tank home for the holidays.  Increasingly now, particularly in the south of the country, they are found outside fending for themselves.

Stick insects are not native to the UK but three species have become naturalised.  These are the Unarmed Stick Insect, the Prickly Stick Insect and the Smooth Stick Insect.  The Unarmed Stick Insect is the commonest, and the Smooth Stick Insect is as yet only found on the Scillies.   There may also be summer sightings of the Indian Stick Insect but this has not naturalised and does not survive outdoors. It is commonly kept as a pet, and reproduces abundantly, laying up to a thousand eggs which hatch quickly and frequently escape their container, or are released.  Stick insects belong in the order Phasmatodea and are generally referred to as phasmids.  They have a variety of names besides stick insects, such as stick bugs, walking sticks, and devil’s darning needles.  They are found in every continent except Antarctica but are commonest in the tropics and subtropics.  Over 3,500 species have been documented, with Borneo alone being home to 300.  All three of our naturalised species are native to New Zealand and it is believed they arrived as eggs hidden in plants imported to supply the horticultural trade over the last century. 

Our stick insects are flightless and feed on leaves, particularly privet and brambles.  They have an unusual life cycle which does not include a larval or pupal stage – no caterpillar or chrysalis.  The population is all female and reproduces without the need for a male (parthenogenesis).  In spring the adult female starts laying eggs, dropping them randomly onto the ground below.  Over the summer she may lay several hundred. The eggs hatch into tiny miniature adults called nymphs.  As they grow the nymphs will shed their skins five or six times before reaching maturity. Most of the adults live only through the summer and are killed by low winter temperatures.  A few make it through, but enough of the eggs survive to hatch the following spring and maintain the population.

These creatures have sneaked into our ecosystem without doing any harm, but this provides an opportunity to study the spread of an imported species, and provides useful information as we encounter more invading species surviving in our warmer climate. If you find a stick insect you can identify it and report it here, ideally with a photo. www.phasmidstudygroup.org/index.php/report-uk-sighting?form=24