Summary of the Characters of Insects, etc. 9 



development takes place gradually, and there is no abrupt change 

 as seen between the larva and the adult in the moth or fly. 

 The final group {i) undergo no metamorphosis. 



B. The Worms or YER^IES are divided into three main groups : — 



(1) Platyhelminthes or Flat Worms. 



(2) Nemathelmiuthes or Eound Worms. 



(3) Annelida or Segmented Worms. 



So far only some of those belonging to the Nemathelminthes 

 ai'e known to be injurious to fruit. But it is possible that the 

 Annelid worms, the Encluifreeida;., which are parasitic on other 

 plants, may occur on the roots of ground fruit. 



The injurious Ifound or Nemathelminth Worms belong to the 

 sub-order Nematoda, and have filiform bodies, the two ends being 

 more or less pointed, and the posterior end of the male, which is 

 usually smaller than the female, slightly curved ; they are round in 

 section, their skin smooth or slightly wrinkled, and the sexes are 

 ■separate. 



The plant parasites belong to a family of Nematoda known as 

 Anguillulidee or Eelworms, which are small, microscopic, thread-like 

 worms. These nematodes live both free in the soil and in the tissues 

 of plants, and others in decaying vegetation. Those which attack 

 plants, and also which are found in decaying plant tissues, have a 

 boring spine. The sexes are separate, and the female produces large 

 eggs. 



EnchytrgeidiB are a family of Annelid worms of small size, 

 never more than 1 inch or so in length, and sometimes found in 

 masses around the roots of plants, and are of a white colour. 



C. MoLLUSCA of importance are confined to the order Gasteropoda. 

 Two families of this order attack fruit, namely, Snails {Helicidss) 

 and Slugs {Limacidse). 



The Helicida; have a shell into which the snail not only can 

 withdraw its body, but which can be closed up at the entrance by 

 means of a structure called the epiphragm. 



The LimacidcC have a very weak shell buried under the skin. 



Both produce eggs, and the young are like the parents. 



