CHAPTER VIII 

 EELWORM GALLS (NEMATODA) 



THE eelworms are comprised in the family AnguilluUdae, 

 belonging to the order Nematoia, or threadworms. 

 It would promote the happiness of the human race if these 

 creatures were non-existent, .for amongst them are some of 

 the most dreaded of human parasites. Those with which 

 we are concerned live a parasitic life in plants, causing 

 remarkable nodosities and tumours. 



Eelworms are very minute, and cannot be seen well with- 

 out the aid of a microscope, the adult in many cases being 

 only I mm. long. The shape is that of an eel. The mouth 

 has a sharply pointed spine, which is used for boring into 

 plants. The ova are hatched within the body of the female; 

 with growth they distend the skin until it becomes a mere 

 sac. Eventually the parent dies, and the young are liber- 

 ated by the rupture of the sac. They attain maturity, on 

 an average, in thirty days. In the case of Tylenchus dtvasta- 

 trix, the larvae bore into the rootlets and become stationary. 

 The adult female emerges from the plant, and is joined 

 by the larger male, which bores its way out later. After 

 fertilization the female degenerates, and at last is nothing 

 more than a broad pouch containing ova and larvae; the 

 majority of the ova hatch out within the body of the parent. 

 There are six or seven generations in one year. 



There are ten species of eelworms in this country, belong- 

 ing to three genera : 



Aphelenchus fragariae Ritz. Bos, on cultivated Straw- 

 berries. 



io6 



