DIAMOND-BACK MOTH, DESCRIPTION OF. 103 



description of the appearance of the moth, and also its Hfe-history, 

 and a few of the easily applicable and approved remedies : — 



Diamond-back Moth. — The si:e of these moths is only about, or 

 rather under, two-thirds of an inch in the spread of the wings, and to 

 ordinary observation when at rest they appear as brownish-grey moths, 

 about the size of furniture moths, but long and narrow in shape. 

 When at rest, and the upper wings laid aloug the back, with the edges 

 meeting, the pale patterns along these edges form diamond- shaped 

 marks, whence the English name " Diamond-back Moth " ; if seen 

 sideways, the curved-up extremity of the wings, as shown at 3 and 4 

 in the figure, is very striking. 



The moths lay their er/r/s for the most part on the under side of the 

 leafage of their food-plants, and we see plainly that this is the usual 

 ravaging ground of the caterpillars ; still, they may be present some- 

 times on other parts of the plants. 



The caterpillars, when full-grown, are about half an inch long, and 

 peculiar in shape, as they taper slightly towards each extremity ; this 

 is a marked characteristic. The colour is usually a delicate green or 

 apple-green, but this is variable; in younger state the larva is often 

 yellowish or greyish, with black head. When near full growth, the 

 head is usually grey or yellowish, marked with small black dots. 

 Each of the first three segments bears a pair of claw- feet ; there are 

 four pairs of sucker-feet beneath the body, and another pair at the end 

 of the tail extremity. When alarmed, the caterpillar lets itself down 

 by a thread, and swings in the air until it cares to return by the thread 

 to where it came from. 



When full-fed, which may be in about four weeks, or possibly less, 

 the caterpillars spin their cocoons, for the most part on the under 

 surface of the leafage of their food-plants, or on stems, or amongst 

 seeds, or any convenient place on or near the plants on which they 

 fed. These cocoons are sometimes a mere open net-work of white 

 threads, sometimes thicker and of a somewhat boat-shaped form. In 

 the former case the colouring of the chrysalis can be distinctly seen 

 through the net ; the characteristic colouring, when mature, is whitish 

 with some black streaks. 



The time spent in chrysalis state may vary (as given by various 

 writers) ; it may occupy from rather over one to about three weeks, 

 but there may certainly be two broods during summer or autumn, and 

 the chrysalids from the last brood of the year remain in this state 

 through the winter. 



Of remedies, one excellent recipe sent me is that found to answer 

 at Edenthorpe during the bad attack of 1891, namely, a mixture of 

 10 cwt. soot, 8 cwt. nitrate of soda, and 1 cwt. ammonia, mixed well, 

 and sown broadcast by hand, whilst the dew was on the leaves, at the 

 rate of 1 cwt. per acre. 



