Phasmids commonly known as stick insects are fascinating insects which are related to leaf insects; grasshoppers; locusts and crickets. Phasma translates from the Latin as ‘phantom, spectre, apparition or ghost’ and this gives a clue as to why they are so named. Most stick insects use camouflage as a protection against predation and have evolved elaborate morphological features to achieve this. A relatively few Phasmids, mostly occurring in South America, are brightly coloured and subsequently are protected by nasty-tasting chemicals. All Phasmids, leaf insects and their grasshopper relatives are herbivorous. They are sometimes confused with mantids which are related to termites and cockroaches and are ferocious predators and in fact one of the many predators from which phasmids need to escape! To confuse relationships further there are mantids which look like stick insects (Mantophasma zephyra) and grasshoppers which also look like stick insects (horse-headed grasshoppers- Proscopia latirostris).
After retirement from the University of Manchester as a Research Associate Dr Yvonne Golding began working as a volunteer in entomology. Previously she had worked on behavioural mimicry in insects notably on hoverflies and how they mimic wasps and bees. Phasmids were initially a hobby interest; Yvonne was a keen member of the Phasmid Study Group and bred many species in culture.
The Manchester Museum already had a small collection of Phasmids most of which were collected 50 or more years ago. Many of these specimens have old names and so need to be re-examined in the light of new classification. One interesting group of specimens was collected during a C.R.A expedition to the Solomon Islands in 1965. Of these we have some strange and unusual specimens one of which a female Phasmotaenia solomense (red arrow in Figure 1) was newly described in 2009 and another Phasmotaenia species with a strange swelling on the thorax as yet undescribed (green arrow in Figure 1). A third very unstick-like and beautiful stick insect is Nisyrus spinulosus (Figure 2).
The collection was soon expanded when many phasmids were discovered among the papered specimens of an Indian collection of P.S. Nathan. These were bought ‘back to life’ by placing them in humid chambers and carefully manipulating legs and antennae to try and resemble some former life-like posture. Many of these specimens turned out to be Carausius species related to the common Indian stick which is often kept in schools. The Carausius genus is very poorly studied which is not helped by the fact the different species really do all look very similar. If anyone has ever kept them in captivity they will know that it is very easy to become over run with them as they can reproduce by parthenogenesis, i.e. they do not need males to produce numerous offspring! Male Carausius specimens are in fact quite rare.
One interesting and new species from this collection Necroscia acutipennis was described by Dr. Phil Bragg with the help of Yvonne who provided measurements. This species is attractive and has wings. Most stick insects were likely to have originally had wings but then, through processes of evolution when they developed morphological camouflage and during periods of diversification, they were lost. Later some species ‘re-evolved’ wings, e,g., Acrophylla species (Figure 3). Being able to fly is a good way to escape from a predator. Generally male phasmids are the better flyers and this helps to find females for mating. Other winged species have even take a lesson from their grasshopper cousins and learnt to jump presumably to escape from predators.
The Phasmid collection was further expanded when Dr Mike Hill donated a number of specimens collected during a wide-ranging biodiversity survey carried out in protected areas of northernVietnamby Flora and Fauna International in 1998/9. The aim of the surveys was to assess the value of sites in protecting biodiversity. These specimens were received in a large sweetie jar of alcohol where they had remained for 10 years! The collection contains over a hundred of specimens which Yvonne mounted and prepared for identification.North Vietnamis one of the richest biodiversity hotspots in the world. Many new species of plants, animals and insects are found there on a regular basis.
The phasmid fauna of this area is understudied so identification of species is difficult requiring the help of phasmid experts; unfortunately these are also a rare breed! Of the many interesting specimens found in this collection is a male relative of the longest stick insect in the world – Chan’s Megastick (Phobaeticus chani) from Borneo – a new species which has been on display in the Natural History Museum in London. The Chan’s stick is a female measuring 56.7cm with body length of 35.7cm not including legs. In the phasmid world females are generally quite a bit longer than males so a male P.chani will most likely measure around 10cm less in body length. Our male Phobaeticus species (see Figure 4), which is yet to be identified to species, at around 20cm in body length may be a contender for the 2nd longest male insect in the world!
Most recently in 2009/10 we have received some phasmids from expeditions of the Russian-Vietnamese Tropical Centre donated to the MM by Dr Alexei V. Abramov from the Zoological Institute in St.-Petersburg, who has undertaken a dozen of field trips to various regions of Vietnam. Amongst the specimens collected by Dr Abramov may be a contender for our smallest phasmid; a fully grown female with very short antennae measuring only 25mm. This Paragongylopus species is as yet undescribed (Figure 5).
A faunistic list of out Vietnamese phasmids is currently being compiled by Yvonne.
1. Whiting, M.F., Bradler, S. & Taylor, M. (2003). Loss and recovery of wings in stick insects. Nature 421, 264-267.
2. Burrows, M & Morris,O. (2002). Jumping in a winged stick insect. The Journal of Experimental Biology 205, 2399–2412.