Sunday, August 5, 2007

Common Field Grasshopper (Chorthippus brunneus)

I am an amateur trying to learn something about everything living in my garden.

Sunning itself on (appropriately enough !), my garden sunlounger I found the grasshopper seen in photo 1 (click to enlarge).

I am used to hearing the chirp of grasshoppers on warm days when I go for country walks hereabouts. I do not tend to hear them in my garden however. The grasshopper in the photo is one of only two I can recall having seen there.

Prior to this posting I knew essentially nothing about grasshoppers. Thanks to reading the short but scholarly Grasshoppers and Bush-crickets (Andrew Mahon, publ. Shire Natural History) however, I am now a little better informed.

For the amateur, learning to identify all the British grasshoppers is a realistic proposition (arguably unlike mastering the beetles !) as there are only eleven species, together with ten species of bush cricket. (Amateurs from 'the rest of the world' be warned however, elsewhere a further eleven thousand species are there to be encountered!).

Bush-crickets can be distinguished from grasshoppers, in part, by their longer antennae (typically, longer than their bodies).

Grasshoppers are vegetarians (some bush-crickets are carnivorous). They overwinter as eggs, typically laid into soil or at the base of vegetation, and, following hatching and a period spent as a grub-like larva, grow to adult-hood through a series of nymph-stages (instars), moulting their exo-skeleton between each stage.
Using the key in the book above and working from my photographs, I was able to make some progress towards identifying my grasshopper. Based on my grasshopper not having antennae swollen at the ends into clubs, I understand that he (or she) can be neither a Rufous nor a Mottled grasshopper. Furthermore, viewed from above (photo 2 , click to enlarge) you can also make out the raised "shoulder blades" ('the keels of the protonum'). The fact that these are curved, rather than straight, also means we can dismiss the possibilty of my grasshopper being a Lesser Marsh.

Unfortunalty, some other features (such as the wing veination) that would have clinched the identity of my grasshopper, I wasn't able to get from my photos. Luckily however, the photo on the front cover of Dr. Mahon's book seems a very close match for my grasshopper - so on that basis I'm going with the Common Field. I say 'luckily' as the Common Field shows considerable variation in patterning and coloration as the photo's here prove. Without the picture on the front of Dr. Mahon's book I might have struggled for longer...always assuming of course I'm now correct! If you know for certain please do leave a comment.

3 comments:

Gaye from the Hunter said...

hi Henry,

here is a site with diagrams distinguishing male from female grasshoppers. Of course, you'd probably need a dead one to examine for identification.

http://www.lucidcentral.org/keys/grasshopper/nonkey/html/Gender/Gender.htm

Australia has zillions of grasshoppers and crickets, some real beauties amongst them. In the summer, my yard is literally hopping with grasshoppers. I haven't as yet attempted to identify any, or even photograph any, for that matter.

Crickets are easier to sex. The female has one tube or spike-like ovipositor extending from the rear, while the male has two much shorter spike-like apendages.

I was pretty damn excited to capture the rear end of a just-moulted male cricket last summer - see here (second last pic):

http://hvbackyard.blogspot.com/2007/01/3-cricket-earns-his-wings.html

This is not a common cricket, so I was rapt to find a female a couple months after my cricket post. The female had an ovipositor well over an inch long - most impressive. I've also discovered a couple of juveniles, and am hoping to search out a female laying in the warmer months.

Did you know that a grasshopper's hearing organ is a large membrane, (tympanum), on the first segment of its abdomen - while a cricket's eardrum is located on the front leg right below the elbow. Interesting critters.

Gaye

Henry Walloon said...

Gaye

Many thanks for this.

I followed the link to your grasshopper page. The closeup photo's are superb!!

Henry

Turf said...

I remember as a youngster I used to grasshoppers all over the place but rarely see them anymore, I don't know if it was because as a child i spent so much time in the grass or woods or wether there are less around today, but it was great reading about them again, it made me remember the childhood days.