By Gary Farmer
Identifying Grasshoppers and their allies is relatively easy compared with other groups of Invertebrates. They are a small group and with a little practice all can be recognised in the field without the need for complicated keys. But the unique thing with Orthoptera is that all (except the Groundhoppers) can be identified by their songs. The problem with this is that the high frequencies used by these Insects becomes inaudible to us as our hearing deteriorates with age. The answer comes in the form of high frequency analysers (Bat Detectors). These have been used very successfully in other counties to increase the number of records for distribution maps. A book recently been produced by the Surrey Wildlife Trust (The Grasshoppers and Crickets of Surrey would you believe) deals with the use of Bat Detectors in some detail and is a very good read. There is also an audio tape of British Orthoptera song available from Harley Books. This is very useful for anyone wishing to learn the songs and if you have trouble hearing the high frequencies then just point your Bat Detector at the hi-fi speakers - apparently this really works. I should be interested to hear from anyone who has tried to identify Orthoptera using a Bat Detector or is willing to bring one along to a field meeting in the Summer.
Meanwhile I shall concentrate on identifying Grasshoppers and Crickets by sight.
Editor's update: Gary has recently bought a modified bat detector and has now discovered how much his hearing has lost its high frequency response, but he is also finding many more grasshoppers.
(see figs 1 & 2)
All Orthopteroid Insects have well developed hind legs for jumping, long antennae (1) and a pronotum (a hard shell covering at least the thorax) (2). The length of the wings (5) is an important identification feature as is the shape of the ovipositor (4) of female Crickets and the shape and length of the Cerci (3) of males. Grasshoppers have short cerci (8), females have ovipositor valves (9) quite different to Crickets and males have sub-genital plates (7). The young or nymphs are miniature versions of the adults and Crickets in particular can be identified at any stage. Always take care when catching and handling specimens as they damage very easily. I find small, clear perspex boxes to be ideal as this avoids handling the Insect at all (make sure that the long antennae of the Crickets fit in). There follows a short description of each of the species. I have deliberately used common names to try to broaden the appeal of this fascinating group of Invertebrates, and make no apologies for doing so.
BALDOCK, DW 1999 Grasshoppers and Crickets of Surrey. Surrey Wildlife Trust. (Available from Surrey Wildlife Trust, School Lane, Pirbright, Woking, Surrey, GU24 0JN) | |
BURTON, J & RAGGE DR 1987. A Sound Guide To The Grasshoppers and Allied Insects of Great Britain and Ireland. Tape cassette. Harley Books. | |
FARMER, G 1999 New orthopteran for Worcestershire - short-winged conehead. Worcestershire Record No.7, page 13. | |
FARMER, G 1999 The other orthoptera (grasshoppers and crickets) of Worcestershire. Worcestershire Record No 7, pages 13-14 |
Crickets have very long, fine antennae (much longer than body). They 'sing' by rubbing their wings together (except the Oak Bush-cricket which 'tap-dances' on a leaf). Crickets are omnivorous, feeding on small Invertebrates and herbage. Females have sword-like (fig. 1) or pin-like (fig. 8) ovipositors.
Figure 1 |
Figure 2 |
Of the eight species of Cricket recorded in Worcestershire, four are very unlikely to be found so I have left three outside of the key - Mole, Wood and House Crickets (the fourth - Great Green Bush-cricket - has been included). Two others included - Long-winged Conehead and Roesels Bush-cricket have not been recorded in Worcestershire but their ranges are expanding rapidly and will hopefully soon be with us.
Mole Cricket (Gryllotalpa gryllotalpa)Nearly 50mm in length. Unlike any other Insect. Hind legs and antennae somewhat reduced compared with other Crickets, front legs enlarged and flattened for digging. |
|
Wood Cricket (Nemobius
sylvestris) Small (approx. 10mm), dark brown. Wings not longer than half abdomen. Pin-like Ovipositor and long, straight cerci (fig. 8). Found under leaf litter. Not likely to occur in the county any longer. House Cricket Pale brown (upto 20mm). Wings as long as body. Pin-like ovipositor and long cerci (fig. 8). Found in heated buildings.(Acheta domesticus) |
Great Green Bush-cricket (Tettigonia viridissima)Very large (upto 50mm) green Cricket. Wings much longer than body. Females ovipositor long and straight, sword-like. Short cerci. |
|
Oak Bush-cricket (Meconema thalassinum)Pale green Cricket upto 20mm long. Females have slightly upturned ovipositor. Males have distinctively curved cerci (fig. 3). |
Dark Bush-cricket (Pholidoptera griseoaptera)Robust, medium sized Cricket to 20mm in length. Various shades of brown with yellow/green underside. Wings very short or absent. Nymphs have pale back and resemble 'wolf' spiders. |
Roesels Bush-cricket (Metrioptera roeselii)Similar to Dark Bush-cricket but easily identified by yellow spots along the side of the body behind the pronotum. A yellow 'U' around the edge of the pronotum is another identification feature. |
Long-winged Conehead (Conocephalus discolor)A slender cricket about 20mm long. Usually green with brown dorsal stripe and brown wings as long as body. Females have long, straight ovipositor. |
Short-winged Conehead (Conocephalus dorsalis)Very similar to the last species but wings only half length of body. Females have upturned ovipositor. |
Speckled Bush-cricket (Leptophyes punctatissima)Small to medium (10-15mm), plump Cricket. Covered in tiny, black dots (even nymphs). Wings almost absent. Brown dorsal stripe when mature. |
Grasshoppers have shorter antennae (about half length of body). Their song is produced by rubbing their legs against their wings. Grasshoppers feed on grasses and other vegetation. Females are larger than males and can be separated by the features shown in fig. 2 of the rear of the abdomen. An important identification feature of Grasshoppers is the pronotum and its side keels (figs. 4 to 7). The shape of these side keels are referred to in keys in all publications, but care (and experience) is needed.
My Key includes the five species so far recorded in Worcestershire plus one extra - Stripe-winged Grasshopper (just in case). Colour variation within species is considerable, ranging from browns and greens to pink and purple. Some have very well defined pronotum side keels, others need to be viewed very closely. Confusion between species is most likely as follows :
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Meadow Chorthippus parallelus (15 - 20mm) and Lesser Marsh C. albomarginatus (15 - 20mm)The pronotums of these two have almost parallel side keels. In Meadow (fig 4) they are least parallel, in Lesser Marsh (fig 5) most parallel. The female Meadow has short wings where as Lesser Marsh has wings as long as body. Meadow is the more brightly coloured of the two and has dark hind knees, with Lesser Marsh being very subdued in colours and lacking the dark knees. Occasionally female Meadow occur with long wings, so watch for those knees and the general tone. |
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Mottled Myrmeleotettix maculatus (12 - 20mm) and Field Chorthippus brunneus (15 - 25mm).Both are 'mottled' in appearance. Field is bigger and
hairy underneath. Both have sharply incurved side keels (fig.
6). Mottled have thickened antennae particularly the males
which are clubbed. |
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Common Green Omocestus
viridulus (15 - 20mm) and Stripe-winged
Stenobothrus lineatus
(15 - 20mm). Similar species but Common Green never has any red or orange on the abdomen whereas Stripe-winged does. Both are fully winged and usually green in colour. Stripe-winged have a white line along the bottom of the wings and a white comma shaped stigma towards the rear end of the wings. The latter species has never been recorded in Worcs but Im sure theyre out there somewhere. |
Groundhoppers are smaller than Grasshoppers and are distinguished by their extended pronotum (as long as the body or longer). They have no song. Groundhoppers are associated with mosses and can be found through out the year.
Two species occur in the county and are both around 10mm in length :-
This has a pronotum as long as the body and a ridge along the back giving an almost 'hunch back' look.
This has a pronotum much longer than the body and a flatter back.
The following key has been kept as simple as possible. I have left out any identification points that require previous knowledge of the group or the need to kill an individual.
First decide whether you have caught a Cricket or Grasshopper by reading the above General Identification.
Then simply read the first question (top left) in the appropriate Key. Answer TRUE or FALSE and follow the arrow to the second question and so on.
I have not included a Key for the Groundhoppers as there are only two and they have been identified above.
I should appreciate any comments after you have tried this Key out so I can make amendments where appropriate.
Green body |
false |
Brown body |
true |
Wings more than half length of abdomen. Row of yellow dots along body, behind pronotum. |
true F |
Roesel's |
true |
false |
|||||
H |
Wings very short
or absent. |
true F |
Dark |
|||
Wings as long as
body |
true |
Wings much longer than body.Very large insect (40 - 50 mm). | true F |
Great Green Bush Cricket |
||
false |
false |
|||||
Body covered in
tiny black spots |
true F |
Speckled Bush Cricket |
Pale green. Wings as long as body. Much smaller insect (20 mm).Male cerci Fig 3. | true F |
Oak Bush-cricket |
|
false |
||||||
Wings half length of body. Brown dorsal stripe & wings. Female has upturned ovipositor. | true F |
Short-winged Conehead |
||||
false F |
Wings full length of body. Brown dorsal stripe & wings.Female has straight ovipositor. |
true F |
Long-winged Conehead |
Pronotum side keels parallel or only slightly
incurved |
false |
false |
Side keels obviously incurved. Narrowest
point appx. half as wide as widest point |
false F |
Put it back and try another! |
|
true |
true |
|||||
Dark hind knees. |
true |
Meadow Grasshopper |
Antennae clubbed/thickened tips (very obvious in males). |
true F |
Mottled Grasshopper |
|
false |
false |
|||||
Hind knees not dark. Colours subdued, pale
brown/green. |
true |
Lesser Marsh Grasshopper |
Width of side keels appx. same width at front as at rear of pronotum fig. 6. Hairy ventrally. Orange or red on abdomen (particularly males). |
true F |
Field Grasshopper |
|
false |
||||||
Stripe-winged Grasshopper |
Mostly green. Red/orange on abdomen. White stigma and stripe on wings. |
false |
Always green dorsally. Width of side keels
at front of pronotum narrower at front of pronotum than
at rear fig. 7. |
true F |
Common Green Grasshopper |
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