68 



the form of a straight tube, until by the time the larva is full-fed 

 the case is half an inch or more in length, and in shape somewhat 

 like one of the old-fashioned horse pistols. The silk of which the 

 case is composed is at first quite white, but gradually darkens, 

 possibly being coloured by some substance secreted bj' the larva, 

 until by the time the pupal change takes place it is practically 

 black. It will thus be seen that apart from any benefit the cole- 

 ophorid larva may derive, during its feeding time, from being 

 furnished with a portable house, it in effect spends the greater part 

 of its life in preparing a habitation for the pupa. 



Coleupliora lineolea also cemmences its larval life as an internal 

 feeder, mining the leaves of black horehound [Ballota niifra), hedge 

 woundwort {Stacht/s st/lvatica) and some other plants. When it has 

 mined a sufficiently large space, it cuts out the cuticles of the leaf 

 and with them forms a case. Many of these leaf -case makers, 

 unable to increase the size of their cases as necessity arises by adding 

 to them, as do those whose cases are made of silk, discard their 

 cases when they have outgrown them, re-enter a leaf, and having 

 mined a sufficiently large space, construct a new and suitable case 

 from the cuticles of the mined portion as before ; the last case made 

 eventually becoming the habitation of the pupa. Some species 

 appear to apply both principles in the construction of their cases, 

 by making them of silk and adorning them with bitten off pieces of 

 the foodplant. (See Plate VIII.) 



As a last example of remarkable pupal habitations I would 

 mention that of Ltjonetia derckella. This species spins a silken 

 cocoon, and suspends it hammock-wise on a leaf of the foodplant 

 by four silken guyropes at each end; and on the leaf, on either side 

 of these supporting strands, it spins a loose, fine, silken web. It 

 has been found that this web is of a very clinging nature and 

 readily adheres to anything that may come in contact with it. It 

 has recently been suggested that its function is to act as an entangle- 

 ment to any marauding ant or other small enemy that may 

 contemplate an attack upon the pupa. 



