Bugs, Cicadas, Aphids, and Scale-insects 201 



smaller genera Serphus and Zaitha have the curious habit of gluing their 

 eggs upright, in a single layer, on the back of the unwilling male (Fig. 276). 

 For a long time it was believed, and is so stated in most entomological books, 

 that the female deposited the eggs on her own back, but it was discovered 

 by Snodgrass that the female Serphus had no ovipositor capable of reach- 

 ing to her back, and by Miss Slater that the female Zaitha is in similar con- 

 dition. Miss Slater observed the egg-laying by aquarium specimens. The 

 male struggles against the indignity, but is actually overcome by the female. 

 Another small aquatic family of few species is that of the Nepidae, or 

 water-scorpions. These dirty brown, stick-like insects can be distinguished 

 from other aquatic Hemiptera by the long slender respiratory tube, made 



up of separable halves each grooved on its 

 inner face, which projects from the tip of 

 the abdomen. Rather sluggish in habit, 

 they lie at the bottom of a shallow pool and 

 lift this respiratory tube up so that its open 

 tip reaches the surface. They are preda- 

 ceous and have the fore legs modified for 

 seizing prey, the other legs being fitted for 

 walking or crawling over the bottom. There 

 are two common genera in the family: Nepa, 

 with flattened oval body less than three times 

 as long (not including respiratory tube) as 



FIG. 277. 



FIG. 278. 



FIG. 277. Young water-scorpion, Ranatra sp. (One and one-half times natural size.) 

 FIG. 278. Eggs of the water-scorpion, Ranatra fusca. (After Pettit; enlarged.) 



broad, and Ranatra (Fig. 277), with elongate slender body more than five 

 times as long as broad. Like the giant water-bugs the water-scorpions 

 lie in wait for their prey, trusting to their inconspicuous color and partial 

 concealment in the mud and rubbish of the bottom to hide them from 

 approaching victims. 



