THE NEUROPTERA 195 



Grasshopper, which is such a familiar sound in the long grass 

 bordering the lanes and fields in summer, is produced by the 

 friction of the hinder thighs against the wing-cases, the insect 

 standing upon his four walking legs, and working his hind ones 

 alternately up and down, so that the inside surface, of the thighs 

 pass rapidly over the veins of the wing-cases. The Acridiidse are 

 provided with organs which are considered auditory in function, 

 as are also the Locustidse ; in the former they are placed on the 

 side of the upper part of the first abdominal segment, and in the 

 latter on the front legs below the knees. 



The Migratory Locust (Pachytylus migratorius) is probably one 

 of the oldest foes of mankind, and records of its depredations have 

 been handed down from the earliest civilisations of the East. 

 Large swarms of these insects consist of an almost incalculable 

 number of individuals, which look like advancing storm clouds, 

 darkening the sky, and when they alight cover the ground and 

 branches of the trees for many miles. In a few hours every vestige 

 of vegetation has been gnawed down and devoured, so that the 

 trees stand with bare and broken branches, stripped of every ves- 

 tige of their luxuriant foliage. Then, as if by some recognised 

 signal, the vast devastating army rises and departs, seeking fresh 

 feeding grounds, and leaving behind it pestilence, famine, and 

 despair. The Locusts have a world-wide distribution ; in the 

 South of Europe, India, China, Africa, and the Rocky Mountains 

 of North America they abound, and from time to time appear in 

 vast, devastating armies. They do not undergo a complete meta- 

 morphosis, the young on emerging from the egg resembling their 

 parents in general appearance, save for the absence of wings. 

 In size they vary from J inch to 6 inches in length, and are power- 

 fully built, with strong hind legs, large heads, and formidable 

 mouth organs. 



The order Neuroptera contains the Termites or White Ants, 

 the May-flies, Caddis-flies, Lacewing-flies, Dragon-flies, Ant-lions, 

 and Ascalaphus, insects which in the adult stage have two pairs 

 of membranous, usually much-veined wings. They form a very 

 diverse order of insects, making it extremely difficult to lay down 

 any definite characters as being common to all. Some, like the 

 so-called White Ants, or Termites, are social, while others are 

 solitary in their habits ; some^are^ vegetarian, while others are 



