THE VICTOIUAN NATURALIST. 



cases, enlarging them as they grow, and never leaving them. 

 Indeed, they seem quite unable to make a second one, although 

 they can repair any damage done to their own or even can adapt 

 to their use such a thing as the finger of a kid glove if they are 

 put into it, spinning a flexible neck to the upper and altering the 

 lower end to suit their ideas of what a back door should be. In 

 the first instance the case is shaped like a very small extinguisher, 

 about one-sixteenth of an inch high, just large enough to hold the 

 little larva. Subsequent enlargements are made at the neck, 

 continually increasing the diameter as required. For the first few 

 months the larva is able to carry the case above itself, nearly at 

 right angles to the branch on which it walks, the peculiar develop- 

 ment of the second and third pairs of limbs making this position 

 an easy and natural one for it to assume. From the time when 

 the case is about one-eighth and until it is about one-half of an 

 inch long it is protected with a covering of pieces of leaves 

 placed all over it without much arrangement, but when it becomes 

 so long that the grub carries it depending from its body, larger 

 and heavier sticks are used, and are always placed lengthwise 

 with the case. The process of fixing on the twigs is best observed 

 in October, when the cases are being rapidly enlarged. The 

 grub increases the length by one-half or three-quarters of an inch 

 before adding any more sticks. It then cuts off the chosen 

 branch at one end and drops the portion not required, and 

 climbing along for an inch or two fastens the edge of its case to 

 the branch. To cut the stick off the grub assumes a position in 

 which it would be far from convenient for a vertebrate to work. 

 The head and thoracic segments are sharply bent backwards on 

 the abdominal segments, so that it can cut away the branch near 

 the mouth of its case and at the same time hold on to the part to 

 be detached. After trimming off the end of the cut stick the 

 grub fixes one end lightly to the mouth of the case, and with- 

 drawing inside cuts a hole about one-quarter of an inch long 

 through the side of its house about half an inch from the top. 

 This operation takes nearly an hour to complete, the tough 

 material being with difficulty cut even by such strong mandibles. 

 As soon as the hole is made the grub comes out through it far 

 enough to reach the stick and cut it free from the case. Again 

 withdrawing, it holds the stick in the hole and sews it firmly to 

 both sides, closing it in so nicely that in half an hour no sign 

 remains to show what had been done, except that another stick 

 has been added to the newly-made part of the case. The whole 

 operation takes about an hour and a half to complete. 



An examination of the case will often give much information 

 respecting its occupant. The full-sized case of a female Metura 

 varies from four to six inches in length, while that of the male 

 seldom exceeds three inches. If it is fixed very strongly to its 



