175 



NOTES ON THE VEGETABLE CATEKPILLAR OF 

 NEW ZEALAND. 



By Alfred Philpott. 



At a meeting of the South London Entomological and 

 Natural History Society, held on Oct. 26th, 1905, there was 

 exhibited by Mr. Step a larva of the New Zealand vegetable 

 caterpillar {Hepialus virescens), and the fungus {Cordiceps 

 robcrtsii) which attacked it. 



This insect-vegetable combination never fails to arouse in- 

 terest, whether the beholder be a trained entomologist or an 

 ordinary observer without any special predilection for the study 

 of insects. It is unfortunate that but little is known of the 

 caterpillar and its parasitic foe, still more unfortunate that 

 several errors have crept into the little we know of its life-history. 

 In almost every account of this curious abnormality it is stated 

 that the insect is extremely rare, that it is found only under the 

 rata-tree {Metrosideros), and that the caterpillar is the larval 

 stage of the handsome green and white moth {Hepialus virescens). 

 These three statements are all contrary to fact. The caterpillar 

 has been found practically throughout New Zealand ; in some 

 cases — for instance, where alluvial gold-mining has been carried 

 on — in great numbers. The dead and dry caterpillar is probably 

 often overlooked, bearing as it does, even with the fungus -spike 

 attached, a close resemblance to a fragment of a dead root. 

 With regard to the larva's invariable association with Metro- 

 sideros, this is so far from being the case that in several districts 

 where the larva has been commonly met with, the rata-tree is 

 unknown. As to the moth into which the caterpillar would in 

 the ordinary course of events develop, Mr. G. V. Hudson has 

 pointed out (' New Zealand Moths and Butterflies,' p. 132) that 

 the supj)osition that H. virescens is the imaginal form is certainly 

 erroneous, as the larva of that species lives in stems of trees, 

 and never goes underground, even to pupate, while the lurva of 

 the vegetable caterpillar is subterranean in its habits. Mr. 

 Hudson suggests Porina mairi in place of H. virescens, but the 

 extreme rarity of this moth renders it improbable. The type of 

 P. mairi was discovered by Sir Walter Buller thirty-nine years 

 ago, and I do not think that a second example has yet been 

 brought to light. It is, I think, more probable that Porina 

 dinodes will turn out to be the correct species. No other moth 

 in this district (Southland) is large enough to warrant the 

 assumption that its larva may be the host of the fungus. When 

 full grown the larva of dinodes is nearly four inches long, and 

 inhabits a tunnel driven in rather an oblique direction to a 

 depth of fifteen to twenty inches. A comparison of fungus- 



