BRITISH GRASSHOPPERS 



873 



holes {spiracles) on the 

 sides of the bod}^ — they 

 possess, hke dragon- flies, 

 bees, and many other fly- 

 ing insects, internal air- 

 sacs which are capable of 

 considerable expansion. It 

 would appear that the 

 dilation or contraction of 

 these air-sacs is, in part, 

 controlled by the insect 

 and, in part, dependent 

 on the space occupied by 

 food and so forth in the 

 insect's body. 



In the destructi\'e mi- 

 grations of Locusts, which 

 occasionally cause enor- 

 mous damage to vegeta- 

 tion, it is probable that 

 there is httle true flying. 

 The insects wait for a 

 favourable wind, and, on 

 its arrival, allow them- 

 selves to be wafted up- 

 wards and carried in the 

 desired direction. Their 

 muscular exertion is con- 

 fined to traveUing as far 

 as may be on an even keel. 

 It is an observed fact that 

 a change of wind causes a 

 swarm of Locusts to come 

 to earth, and their abihty 

 to do this seems most easily 

 accounted for by assuming that they have, 

 when their bodies are empty (migration 

 would be otherwise unnecessary), a fairly 

 complete control over their air-reservoirs. 

 The appearance of an approaching swarm 

 of Locusts has been hkened by several 

 observers to that of a snowstorm, and the 

 weight of one particular swarm which 

 passed over the Red Sea in 1889 was 

 estimated at 42,850 millions of tons ! 



Dilatable air-sacs appear to be either 

 rudimentary or wanting altogether in 

 Long-horned Grasshoppers, and it is 

 perhaps this deficiency which prevents 

 their migrating, hke Locusts, en masse, 

 and which inchnes them to a mixed diet 

 of animal and vegetable food. Several of 

 our Long-horns possess an ample expanse 

 of wings, but none of them can be termed 

 strong flyers. The utmost that can be 

 said for the wings of either L. viridissima 

 111 



THE SMALL WOOD GRASSHOPPER 

 (TETTIX BIPiWCTATUS). 



At the top are two cabinet specimens 

 which have not been in any way 

 posed for the camera. The distinctive 

 form of the live Tettix can be well seen 

 in the two lower illustrations. 



or M. variiim is that they 

 serve to break a fall. L. 

 piinctatissima has no wings 

 to speak of ; neither has 

 T. cinereiis. 



I am inchncd to think 

 that British Long-horns 

 are normally insectivorous 

 when mature, and that 

 they wait for their prey to 

 come to them. Sometimes 

 they will slowly ach'ance 

 to the attack (I have seen 

 the Great Green Grass- 

 hopper so stalking a 

 Burnet ]\Ioth), and, if the 

 object aimed at happens 

 to be asleep, he will be 

 eaten — or at least the fat 

 portion of him, the wings 

 being, as usual, pulled off 

 and thrown aside. 



Besides the distinctive 

 differences between Short- 

 horned and Long - horned 

 Grasshoppers which are to 

 be found in the length of 

 their antennae, the develop- 

 ment of their ovipositors 

 and the nature of their 

 food, a further and im- 

 portant difference exists in 

 the character and mechan- 

 ism of their chirrup. Mr. 

 Malcolm Burr, to whose 

 "British Orthoptera" I would refer the 

 reader for an excellent systematic account 

 of British Grasshoppers generally, de- 

 scribes the "cliirrup," or stridulation, of 

 three common Shorthorns as follows : 

 S. viriduliis — loud and prolonged, begin- 

 ning low and gradually rising until it 

 has reached a certain pitch ; 5. hicolor — 

 a short " tzz-tzz-tzz " ; and S. parallel us 

 — " tss-ssz-szz-zzz-zz-z." The last phrase 

 I must confess perplexes me, but I am 

 reheved to find that British entomolo- 

 gists have as yet dechned to follow the 

 Americans in reducing Grasshopper notes 

 to formuke in which T = the temperature 

 of the air, H the humichty, N the number 

 of stridulations per second, and so forth. 

 In Short-horned Grasshoppers stridu- 

 lation is effected by the friction of one 

 liind-leg against the elastic edge of the 

 wing-cover on the same side of the body. 



