234 



EXPERIMEXTAL FARMS. 



64 VICTORIA, A. 1901 



THE PALMER WORM 

 (Ypsolophus pometellus, Harr.). 



Attach. — Slender greenish white caterpillars, reddish brown on back, with a 

 central stripe down the middle, bordered on each side with white irregular bands ; 

 ■when full-grown, a little over half an inch in length ; feeding on the leaves, and some- 

 times on the surface of the fruit. 



Complaints of the work of this insect have been received from several localities 

 during the past seasoii, particularly from sections along the northern shore of Lake 

 Ontario. It has also been found as far north as Ottawa. Judging from reports 

 received, the Palmer Worm has confined its attacks chiefly to the apple. From a' letter 

 received from Mr. A. W. Peart, of Freeman, Out., dated June 19, the following is 

 extracted : — 



'I enclose in small box some worms which are very plentiful here at present, 

 working particularly on the apple. They vary in size from a i of an inch to g of an 

 inch in length. They are a light yellow with two stripes running lengthwise on either 

 side of the back. Their most marked characteristic is their rapid motion. Take one 

 in the palm of the hand, and touch it, it wriggles and jumps an inch or two with 

 rapid lightning-like contortions. When you catch one, it is hard to hold. Like 

 the cankerworm, it spins a thread when you disturb a branch, and lets itself down, 

 and you can see it swinging ; but luilike the cankerworm, it does not loop in travel- 

 ling. I find it in holes eaten in the young apples, and I think it is responsible for 

 at least a portion of the cavity, if not all. On some trees, with their leaves badly 

 riddled, you can find them by hundreds.' 



Letters of a similar nature to the above have been received from Oakville, 

 Adolphustown, and other points. • 



The life-history of the Palmer Worm is fairly well known. When the caterpillars 

 are young they eat only the soft tissues of the leaves, but, as they mature, they devour 

 the whole of the foliage, with the exception of the coarser veins. This is especially 

 so when the larvae are numerous. When the infestation is not of a serious nature, 

 the caterpillars may be found feeding in a folded portion of a leaf. These larvae 

 are extremely active, and, as has been observed above, if a tree on which the cater- 

 pillars are at work is suddenly jarred, the larvae will drop from their feeding places, 

 and suspend themselves in the air by means of silken threads. If one is placed on 

 any flat surface, it wriggles, and when touched moves with remarkable rapidity. 



When full-grown, the caterpillar is a little over half an inch in length, and in 

 general appearance is a greenish-white larva, with the dorsal area reddish brown, 

 having a central dorsal stripe widely bordered on each side with white irregular bands, 

 a little wider than the medio-dorsal stripe. The head is honey-yellow. The thoracic 

 shield is transparent and inconspicuous, having the hind margin borderded with black 

 for half its length, the black edge terminating with a hook forward on each side of the 

 shield, leaving a wide central opening. The stigmatal fold is prominent. Along the 

 dorsal area are two series of black piliferous spots, those on the anterior portion of each 

 segment closer together than the others. Spiracles whitish, difficult to detect. The 

 body bears a few slender bristles, one from each spot. 



When mature the caterpillar changes to a chrysalis, usually in a fold of a leaf, 

 and produces the moth in about fourteen or fifteen days. Those received on June 28 

 spun up on July 2, and the moths appeared on July 16 and 17. The moth is a delicate 

 little creature of about five-eighths of an inch in expanse of wings. It is of a grayish- 

 brown colour, with a purplish or golden reflexion ; some specimens are of a tawny 

 yellow. The forewings are dotted with small dark chocolate-coloured spots. The 

 margins of lhe dusky lower wings are deeply fringed. 



Remedy. — The remedy for this insect is spraying with the arsenites. A hymen- 

 opterous parasite was bred from this specie* by Mr. C. H. Young, of Ottawa. 



