557 



Tapinoma melanocephalum, F., and the wasps, Vespa orientaMs, L., 

 and T"^. cinda, F. , are attracted to the infested fields. The spots where 

 the nymphs feed are frequently attacked by fungi, which penetrate 

 into the tissues of the plant, causing decay and death, and even 

 if this does not occur, the formation of saccharine matter in the stems 

 is pi'evented and the resultant crop is very poor. After passing 

 through five instars, the development of each of which is followed 

 in detail in this paper, the nymph becomes lethargic and finally 

 stationary on the leaf ; it then moults for the last time, emerging as 

 an adult. The adults move about actively on the leaf-surfaces and 

 jump from one to another, in this way travelling long distances ; 

 they cannot, however, fly far. Females apparently occur in far 

 greater number than males ; the proportions have not as yet 

 been discovered, but further investigations will be conducted in 

 this connection. Climatic changes seem to effect a great difference 

 in the numbers of adults ; hot winds during April and May reduce 

 the nmnber of hoppers considerably ; but if heavy rain accompanied 

 by high ^N-inds occurs during that period, the majority of the adults 

 perish. During the latter part of summer and the rains, the complete 

 life-cycle of a hopper averages about 52 days ; as the cold weather 

 Lidvances the period lengthens to about 130 days. Oviposition occurs 

 from March to December, the adults from the last eggs laid appearing 

 in the following March ; there are from 3 to 4 broods in a year, which 

 overlap, so that nymphs and adults are found throughout the year 

 on the canes. The insect attains its maximum development during 

 July-October, while canes are at their critical time of growi:h. 



Enemies of P. aherrans include predators and parasites. The 

 former are not important ; Cremastogaster ivalshi, For., carries away 

 some eggs, and spiders do some good by catching the nymphs in their 

 webs, i^arasites include three Chalcidids infesting the eggs, two of 

 which have been identified as Ooencyrtus pyrillae, Crawf . , and Tetrasti- 

 chus pijrillae, Crawf. During 1914 these parasites aj)peared early in 

 August and reached their maximum development in early November, 

 when practically every egg of P. aherrans in the field was parasitised ; 

 thereafter both egg-masses and parasites disappeared. A table and 

 a graph show the extent of parasitisation of the egg-masses in 1914. 

 Two species of Dryinids, Dryinus pyrillae and Chlorodryinus pallidus, 

 parasitise the nymphs to a considerable extent ; the former was found 

 mostly on nymphs in the 2nd to 4th instars, from August to November. 

 C. pallidus was previously known in Austraha and is now recorded 

 from India for the first time, where it occurred in large numbers, 

 from early November 1914 to mid-January 1915. At first the nymphs 

 of P. oberrans seem almost unaffected by the parasitisation, but before 

 the development of the Dryinid grub is complete the nymphs are 

 stationary on the leaves and they die with the emergence of the grub. 

 C. palh'dtis was observed to be attacked in the pupal stage by two 

 species of hyperparasites. The Stylopid, Pyrilloxenos compactus, 

 Pierce, parasitises both nymphs and adults of whichever species of 

 leaf-hopper happens to be most abundant during the year. Nymphs 

 may be observed jumping from plant to plant with as many as seven 

 parasites of both sexes on their bodies. The emergence of the male 

 parasites apparently laceiates the tissues sufficiently to cause the 

 (jieath of the host. 



