THE SWIFT MOTH CATERPILLAR AND DAFFODILS. 221 



grub of the narcissus fly. The narcissus fly lays its egg in the foliage, 

 and the grub which hatches out makes its way into the centre of the 

 bulb, which it completely destroys, and ultimately it eats its way out, 

 though it is occasionally found in the middle of the bulb when it has 

 been lifted and dried off. There is nearly always found a hole from 

 the base into the centre of the bulb, and sometimes another hole out on 

 to the shoulder of the bulb. 



In a bulb attacked by the caterpillar one or more holes are seen to 

 have been bored into the bulb, generally into the base ; but the holes are 

 not deep, and it is usually easy to see that they do not extend into the 

 centre of the bulb. More rarely it may be found that a considerable 

 part of the base of the bulb has been eaten away in an irregular patch. 

 In either case the havoc wrought on the plant is sufficient to impair its 

 vitality seriously and often to destroy it as effectually as though it had 

 been visited by the narcissus fly. Apparently the caterpillar, having 

 eaten a certain distance into the bulb, leaves that spot and begins 

 again at a fresh place or on another bulb. 



This method of attack was particulary noticeable in the case of some 

 colchicums, the smooth bulbs being pitted all over with little holes about 

 a quarter of an inch deep. But the colchicum bulbs were not very 

 seriously injured by the treatment, the bulb being, as it were, merely 

 a storehouse for reserve material, and the growing shoot produced from 

 the side of the bulb was not generally affected. 



The caterpillar when full grown is about one inch in length. The 

 body is white and the head brown in colour. 



In the spring it makes its way to the surface of the ground and spins 

 itself a cocoon. This proceeding begins in April and continues through 

 May into the early part of June. The earliest date on which I have 

 found a caterpillar spinning its cocoon is April 15, and the latest during 

 the first week of June ; but by the middle of May most of the caterpillars 

 have turned into chrysalides, and may be found a few inches below the 

 surface. 



The chrysalis is of a yellowish chestnut colour, usually about seven 

 eighths of an inch long and three-sixteenths of an inch in diameter, and 

 when disturbed it wriggles a good deal, a habit which often leads to its 

 detection. It is, however, not always easy to find the chrysalides in 

 the soil, even when the condition of the plants raises a suspicion of their 

 presence, and a careful search is made, and although the subsequent 

 finding of the empty shells shows they have in fact been there, and have 

 escaped discovery. 



The chrysalis stage continues for about three weeks, and the insect 

 then wriggles to the surface and the moth escapes. I have some reason 

 to think that this stage may be slightly shorter in bright warm weather 

 than when it is cold and damp, but the difference is not very great. 

 The hatching out of the moths commences towards the end of May and 

 continues through J une. The female moth is nearly an inch and a half 

 across the expanded wings, and just under an inch in length of body, 

 the abdomen being of approximately uniform thickness. The male is 

 one inch and an eighth across the wings, and five-eighths of an inch 

 in length of body, the abdomen tapering towards the tail, and being 



