434 DICOTYLEDONS AND CONIFERS 



After a time the popular belief grew that the disease was due to the 

 affected animals being fed on ragwort which was very abundant in 

 the district. On investigation by the officers of the Veterinary Depart- 

 ment this was found to be the case. The disease, which is cirrhosis 

 of the liver, is by no means confined to New Zealand, but has been 

 known under other names in other countries, notably in parts of 

 North America, wherever Senecio jacobcea abounds. Thus in Canada 

 it is known as the Picton cattle disease. 



Since the vast increase of this weed, there has been a corre- 

 spondingly enormous increase in numbers of the New Zealand magpie 

 moth — Nyctemera annulata — the larva of which feeds mainly on this 

 plant. In summer the moths are frequently to be seen almost in 

 clouds in the infested districts. The larva is hairy and distasteful to 

 birds, and there is apparently nothing to Check its increase, but it is 

 quite unable to cope with the vast increase of the weed. 



In June, 1913, ragwort was reported as common on the Volcanic 

 Plateau, an area of 5,000 acres lying to the south of Mangatautari 

 and west of the Waikato River, and coincidently with its spread has 

 been an enormous increase of Nyctemera annulata. 



In the weed-infested districts bee-keepers complain that their 

 summer honey is dark-coloured, and so strongly flavoured with the 

 nectar of the ragwort, which is developed in great profusion, that it 

 is almost unsaleable. 



The plant flowers from Feb. to April. In Europe it is visited by 

 Apis mellifica, Bombus lapidarius, B. terrestris, B. hortorum, Eristalis 

 tenax, Lucilia ccesar, L. sericata and Calliphora erythrocephala. 



Senecio erucifolius, Linn. 



According to the report of the Agricultural Department for 1897 

 this species of giant groundsel occurs along with the preceding in 

 Southland. 



Senecio aquaticus, Hill 



Recorded in the Manual (1906) as collected by the Rev. F. H. 

 Spencer in the BuUer Valley. (Fl., Feb. to March.) 



Senecio mikanioides. Otto. Climbing Groundsel 



First recorded by Kirk in 1869 from the Auckland district and 

 in 1877 from Wellington, as S. scandens, DC. Originally a garden 

 escape, it soon became established in the district. It has also spread 

 in many parts of the North Island, and is occasionally met with in 

 the south, e.g. in the neighbourhood of Dunedin. It does not stand 

 frost, but will grow in any sheltered locality at the edge of the bush. 

 In Taranaki it grows on the banks of many of the streams, and climbs 



