BRITISH INSECTS 



so that, if both kinds of insects are found taking lodgings 

 in a household, the owner must decide for himself which, 

 if either, of the two he will decide to harbour. We 

 would not, in any case, advise the introduction of the 

 Cockroach to combat the Bug. In addition to Cimex 

 lectularius, there are three others of the same genus 

 which seem to restrict attention to Bats, Pigeons, and 

 Swallows, and have, in consequence, been accorded 

 the specific names of C. piptstrellt, C. colombarius, and 

 C hirundinis, respectively. There is one more species 

 which deserves mention, that is the Masked Bug which 

 somewhat resembles the Water Scorpion described later 

 on. It measures almost an inch in length, and has 

 black wings. The larva and adult both prey upon other 

 insects (including the Bed Bug), and presumably the 

 popular name has been acquired because the larva has 

 the habit of camouflaging its body with some substance, 

 so as to stalk its prey unobserved. The long-legged 

 Water Measurers (Hydromeira), and also the Pond 

 Skaters {Gerrida), are close relatives of the Land Bugs. 

 They will be known by sight to almost everyone who 

 visits a pond or stream, and their movements (the Mea- 

 surer's slow, the Skater's quick) rarely fail to excite 

 interest. This introduces us to two further pond- 

 dwellers in the persons of the Water Boatman and Water 

 Scorpion. The first-named insect {Notonecta glauca) (Fig. 

 8), has a smooth, flattish, yellowish-brown body about 

 half an inch long, but its chief appeal to the popular 

 mind is its habit of floating upside down, and propelHng 

 30 



