1903.] E. P. Stebbing— Life-history of Arbela tetraonis. 255 



in June and a moth on 3rd July) ; December in North Arcofc (witb 

 pupa in June) ; the same month in Godaveri (with pupa and moth in 

 March) ; full-grown caterpillars and almost mature pupae in Cuddalore 

 on June 1st and what appear to be nearly mature larvae in Nellore 

 also in June. 



We have yet to ascertain the period spent by the larvae in tliis stage 

 of its existence. In some instances in the case of allied families two to 

 three years are passed in this stage. So little is known about the larvae of 

 this and the Cossidae that only the eater-pillars of Duomitus niger (the 

 'black borer' of coffee planters) and Zenzera coffeae (the white borer of coffee 

 planters), are described in the Fauna and no larvae of the Arbeliclse. They 

 are considered to spend nearly, if not over, a year in the larval stage. In 

 the case under consideration I am of opinion that the larva spends less 

 than a year in the grub stage, and the difference may be due to the fact 

 that whilst the former two feed on wood the latter confines itself until 

 full-grown to a bark diet. Whatever the period may be however which 

 the larvae passes in its grub stage the greater portion of it is spent upon 

 the bark of the tree and not inside the wood. 



I have said that the eggs are laid upon the bark, and they may be 

 so deposited in patches, and if so the young larvae may be gregarious for 

 a time after hatching out. This is to some extent borne out by the fact 

 that the thinner bark of the trees is seen to be eaten off in patches. 

 If they are however gregarious at first this condition would not 

 appear to last long since the greater part of the larval life is spent 

 in a solitary state, and at this period the grub constructs for itself a 

 covered-way gallery resembling a glorified termite gallery running up 

 the outside of the bark. This covered way is formed of particles of 

 its excreta bound together with a fine silk. Externally the appearance 

 is simply that of a mass of excrementous particles. These covered ways 

 curl round or run up or down the stem of the tree and are very con- 

 spicuous, being from one-third to one-half inch in breadth externally and 

 from nine inches to as much as eighteen inches in length. They are 

 reddish-brown to, in parts, black in colour and form raised galleries on 

 the surface. Sometimes the gallery completely encircles the stem, the 

 tree being then ringed ; at others it is taken in a spiral manner up or 

 down the tree. The covered ways have a more or less uniform width 

 throughout their length and from their appearance the larva would 

 seem to add to them at the sides so that the internal chamber remains 

 uniform in width throughout its length. Generally only two to three of 

 these galleries are to be found upon any one tree and then generally 

 far apart, and it would therefore appear probable that if a considerable 

 number of eggs are laid together in a patch there must be a high niortal- 

 J. ii. 35 



