CLASSIFICATION AND DESCRIPTION OF COMMON INSECTS 371 



lected under them, (b) Liming the soil is also useful, (c) If slugs 

 have collected on the plants dust them with a mixture of lime 5 parts and 

 fresh hellebore i part. Providing the hellebore is fresh this is very 

 effective and does not injure the plants, (d) Use the bran-arsenic- 

 treacle mash as for cutworms, (e) Broadcast salt at night in misty 

 weather. (/) Use poultry. (See Farmer's Bull. 959, U. S. Dept. Ag.) 



Nematodes or Eelworms 



Common Eelworm (Heierodera radicicola Greef). — Eelworms, 

 although not closely related structurally to insects may be considered 

 here in connection with them. They are common pests of roots and 

 underground parts of plants, producing root-knots, galls or rough 

 warty surfaces. Tomatoes indoors and potatoes outdoors are often 

 injured, especially when grown on sandy soil. The males are micro- 

 scopic in size and resemble miniature eels, hence the name eelworms. 

 The females are glistening pearly white and pear-shaped or rounded, 

 about half the size of a pin head. 



Life-history. — The eggs are oval-shaped and are produced by 

 the females in great numbers in the knots or galls. They hatch in 

 a short time and the young eelworms seek new quarters and feed upon 

 the roots of plants producing the characteristic deformities. They 

 may pass the winter in their host; or it may be on other plants. The 

 young forms may even encyst themselves in the soil. 



The following plants are liable to be severely injured by Nematode 

 attacks (Gilbert, Farmers' Bulletin 625): Soy bean, beet, carrot, 

 celery, cow pea, crimson clover, cucumber, lettuce, peach, potato, 

 squash, tobacco, tomato, watermelon; less severely: alfalfa, asparagus, 

 Lima bean, cabbage, sweet clover, cotton, onion, garden pea, radish, 

 spinach, strawberry, vetch. The following plants are largely immune: 

 barley, corn, grasses, oats, rye, wheat, and cow peas (some varieties). 



Control. — Infested soil in greenhouses may be sterilized by steam, 

 carbolic acid (1:20) or formalin; mix the soil intimately with gas- 

 lime; rotation of crops; summer fallow; plant clean nursery stock. 



