30 MILLIPEDES 



the small size of the animals constitute their only means of defence. 



The commonest parasites of millipedes are Gregarinidea. Thus 

 it has been found that of 165 lulus and Paraiulus spp. examined, 

 158 were parasitised by Gregarines, 26 out of 32 Polydesmus sp. 

 and 6 out of 16 Lysiopetalum sp. The parasites had no seasonal 

 cycle and all stages were found together. No doubt the lulidae 

 were so persistently parasitised on account of their gregarious 

 habits and diet of rotting wood and vegetable matter. Lysiopetalum 

 spp. which live under stones in drier places and are somewhat 

 solitary are far less parasitised. After Gregarinidea, Coccidia and 

 Flagellates are the most numerous parasites of myriapods. It is 

 probable that a high degree of tolerance has been reached between 

 parasite and host and unlikely that the former do any harm. Most 

 of the millipedes from the Amazon basin are infested with nema- 

 todes and these parasites are by no means uncommon elsewhere: 

 while several Diplopoda are intermediate hosts of cestodes of the 

 related families Dilipididae and Hymenolipididae (Remy, 1950b). 

 No doubt phytophagous animals which consume a certain amount 

 of soil with their food are especially liable to infection by these 

 animals. 



Numerous mites of two ecologically separate and systematically 

 unrelated groups are found on millipedes. In the first, which in- 

 cludes Mesostigmata and Acaridae, the myriapods are used merely 

 for transport (phoresy)"j* while the second group, all Mesostigmata, 

 includes more or less intermittent commensals which live freely, 

 not attached to their host and feed on detritus. Evans (1955) has 

 reviewed the Laelaptidae parasitic on myriapods. Sometimes the 

 body of a sick millipede may become covered with a multitude of 

 little mites but usually these parasites are confined to the head, 

 front legs and gonopods whence they cannot easily be removed. 

 The adults of one species of mite found on lulidae in Natal and 

 Zululand, feed upon the liquid secreted by the repugnatorial 

 glands of their host. 



An interesting case of aggressive parasitism of a millipede by a 



fly of the family Phoridae which battled with a huge black lulus 



sp. for several hours has been recorded, and larvae of another 



species of Phoridae, Megaselia juli, have been found in a number 



t See discussion of phoresy on p. 103. 



