affecting the Potato-crops. 



77 



shorthand apparently triarticulate (fig. 18, magnified; 19 is to 

 show the leaping apparatus in another species). 



These minute animals are nourished by eating the parenchyma 

 of the green leaves, but some species feed on fungi. In Nova 

 Scotia the crops of turnips and cabbages are principally de- 

 stroyed, whilst in the seed-leaf, by some Smynthurus, the size of 

 a pin's head, and nearly globular. It hops with great agility by 

 means of its forked tail, and may be found on every square inch 

 of all old cultivated ground, but it is not plentiful on new land. 

 As these "Ground-fleas" will not remain on damp ground, they 

 may be expelled by sprinkling salt over the land after the seed is 

 sown and well rolled down, or a thin layer of sea-weed spread 

 over the drills is a perfect security against them.* 



An allied Genus called Podura has very lately been accused of 

 being the origin of the potato-disease. VV. P. says — 



" First, in an early stage of its existence, it lives on decayed vege- 

 table matter, which it collects by burrowing into the earth ; secondly, 

 it occurs in numbers sufficient to cover nearly the whole surface of the 

 earth ; thirdly, it collects, as a means of existence, a substance which is 

 poisonous to vegetables. It has power to infuse this into living plants 

 by burrowing into the parenchyma. The poison is circulated through 

 the system, vital action becomes suspended, mildew immediately fol- 

 lows, and in less than three days some of the plants attacked are dead 

 vegetable matter, food for the offspring of the newly-discovered 

 Podura."-\ 



Dr. Lindley very justly adds, {< Insects are not the cause of 

 the potato-disease." 



Cimicid^, or Plantbugs. 



It is somewhat remarkable that whilst portions of these crea- 

 tures, as we have already shown, are destined to live upon Aphides, 

 and so preserve our vegetables, others have an opposite taste, and, 

 like the Plant-lice, pierce the cuticle to feed upon the juices, 

 causing similar injury by parching up the leaves, or covering them 

 with blotches. 



The appearance of various species of Plant-bugs, their larvae 

 and pupae, upon the potato-crops, excited the attention of agri- 

 culturists, some of whom were at once disposed to attribute the 

 prevalent disease to these insects. The truth is, when an un- 

 known malady first visits us, it is natural that every one inte- 

 rested should endeavour to find out the origin, consequently every 

 imaginary influence is taxed as the cause by the speculative mind; 

 and from the little attention that is paid by the farmer and gar- 

 dener to the economy of insects, they are led to believe that cer- 

 tain tribes of animals are the culprits, because they chance to be 



* Halifax Times, 



t Gardeners' Chron. vol. viii. p. 702. 



