38 



Vermes, insects, and Arachnida, while a species of Sphex prey upon 

 them, and many birds and insectivorous mammals appear to eat 

 them ; so that it will be seen that cockroaches, like mediaeval walled 

 cities, have a long list of enemies, both internal and external. 



We will now leave cockroaches ; and as you have recently heard a 

 most interesting account of the Mantodea and Phasmodea from Mr. 

 Stanley Edwards, we will pass straight on to the Acridiodea. 



The Acridiodea are a very numerous group, subdivided into several 

 families, of which some are well monographed ; but the system of the 

 family Acridiidae, the most numerous, is in a very unsatisfactory con- 

 dition. 



The Acridiodea is the first of the Saltatorial sections, and also the 

 first section in which the insects have the power of stridulation. The 

 posterior femora are furnished inside with a row of knobs ; by the 

 friction of these against the rough and thickened veins of the elytra 

 the sound is produced. The male sits and calls to his mate when the 

 sun shines, but when the collector is about he advertises his where- 

 abouts, for with a sharp ear and a little practice it is not difficult to 

 distinguish the various species by their song. 



During the act of copulation the male stridulates violently, and in 

 this connection we have noticed a curious fact. Professor Poulton 

 has observed that the male of Podisma pedestre, in which the elytra 

 are far too short to be reached by the legs, manfully attempts to 

 stridulate, carried away by the excitement of the moment, with the 

 result that he only succeeds in moving his legs in the air, pathetically 

 endeavouring to reach his rudimentary elytra. If these insects are 

 able to chirp it is but logical to assume that they can hear. The ear 

 is a tympanum or opening on each side of the first abdominal 

 segment. 



One of the most curious families is the Pneumoridse. In these 

 insects the female is very considerably larger than the male, and 

 possesses rudimentary wings. The male is remarkable for the extraor- 

 dinary distension of the abdomen, which is swollen and hollow, 

 resembling a balloon. This acts as a sounding-board for the creature's 

 stridulation, which is said to be very loud and shrill. The family is 

 peculiar to the extreme south of the African continent. 



Two other peculiar families are the Proscopidse, which have the 

 appearance of Phasmodea, and the Eumastacidse, which are generally 

 odd in appearance, and mimic small dragon-flies and dried leaves in 

 a wonderful manner. 



Anyone who has collected on the Continent is familiar with those 

 grasshoppers with bright blue and red wings. It is a common error 

 to suppose that they belong to one species ; as a matter of fact, it is 

 a somewhat confused subject, but I will endeavour to make it clear. 



On high woody mountains in Southern Europe there is a heavy 

 black grasshopper with scarlet wings tipped with black. This 

 is Psophus stridulus (L.). I have found it most common in the 

 mountains of Savoy and Bosnia. 



