INSECTS 39 



except to the other pond inhabitants, but to these unfortunates 

 they are a cause of continual anxiety. 



Firstly, the scorpions lie concealed in the mud or amongst 

 the vegetation, and make sudden unexpected snatches then 

 Corixa, and Notonecta, the water-boatman, spend their time 

 hunting all that comes their way. 



Nepa Cinerea, the water-scorpion, is the largest aquatic bug 

 found in our country. The creature, if judged by its appear- 

 ance, would be considered decidedly uninteresting. In colour 

 and shape it resembles a small brown leaf, and to make this 

 similarity yet more complete, its thinness is such that, until it 

 strolls majestically from amongst the weeds, it is difficult to 

 believe that it is really an animal. Its flattened body is ter- 

 minated by a thin tube which divides readily into two parts 

 longitudinally. When air is required the insect pushes it 

 through the water-film, but sometimes Nepa will save itself 

 a journey by utilising the bubbles of oxygen produced by 

 plants beneath the surface. 



Nepa, like all other insects, has three pairs of legs : the front 

 pair are not used for walking as one might suppose, and except 

 for brushing aside the weeds through which the insect is pro- 

 gressing, they are only used for capturing its prey. We might 

 roughly say that the front pair of legs serve as hands, and 

 good ones too. The unfortunate tadpole that incautiously 

 approaches is seized, and without more ado is drawn towards 

 the ever-ready beak, however violently it may struggle. 



Even the caddis-worm, so well protected from enemies, falls 

 a prey to Nepa. The latter seizes the caddis case and holds it 

 in the most affectionate manner, and then by carefully moving 

 it along until the small end is in a convenient position, forces 

 one of those most useful front legs into the case, similarly as 

 the fisherman uses a blunt pin. Then gradually the unfor- 

 tunate caddis-worm nears the entrance of its case, but the 

 scorpion knows its work too well, and cautiously shifting the 

 case the leg is pushed in and the larva driven from its shelter. 

 No sooner has its head appeared, than Nepa slowly but care- 

 fully drives its sharp beak into the soft portion of its victim, 

 just behind the head. The case falls on to the mud below, and 

 Nepa holds the owner in its embrace, and gradually sucks out 

 the juices. The coal-black eyes of the murderer, so prominent 

 and yet so small, are typically cruel. 



The female Nepa lays her eggs on water-plants : each egg is 

 adorned with seven filaments, which are thought to collect air 

 for the embryo inside. The larvae are similar to the adult in 

 appearance, but have neither the long breathing-tube nor 



