UNCLASSIFIED PESTS 



343 



these organs has con\'inced the writers that they are well 

 adapted for this purpose. It is true that millipedes prefer 

 decaying vegetable matter but it is also w^ell known that they 

 will attack healthy roots when their favorite food is not avail- 

 able. Under such conditions they select, wherever possible, 

 a part that has already been injured by some insect or that is 

 affected with some disease. Roots or 

 tubers that have been eaten into often be- 

 come infected with fungi or bacteria, causing 

 decay. 



Numerous species of millipedes belonging 

 to several genera have been found injurious 

 in America but their life history and habits 

 do not appear to have been carefully 

 studied. 



The greenhouse millipede, Orthomorpha 

 gracilis Koch, is of tropical origin and is 

 common in greenhouses in Europe and 

 America. In this form the body is some- 

 what flattened and the segmentation is 

 very distinct. On the side of each seg- 

 ment is a thin horizontal plate which in 

 the posterior segments is acutely pointed 

 behind. The full-grown millipede is nearly an inch in 

 length, chestnut-brown above, with the lateral plates 

 yellowish. 



The commonest millipedes that are injurious in the field 

 belong to Julus and related genera. These forms are elongate, 

 cylindrical and usually piceous in color with the legs and under 

 parts pale. When at rest they are usually coiled in a circle. 

 Reproduction is by means of eggs, which the female deposits 

 in a mass covered with j)ellets of earth glued together to form 

 an egg-cocoon. The eggs are laid in the spring and again in 

 the fall and hatch in about two weeks. The young differ from 



Fig. 213. — A car- 

 rot injured by 

 slugs and milli- 

 pedes. 



