142 TfJRNIP. 



from Lambouni, near Swindon, Wilts, as samples of an infestation 

 which had not been observed before in the neighbourhood. 



After this date no further reports of this infestation were sent me, 

 which gives the time over which presence of Diamond-backs in some 

 one or other of their different stages extended in 1892, as being from 

 the 17th of May to the 29th of July, and, so far as can be judged by 

 reports sent to myself, the attack was far less prevalent than in 1891. 

 The localities from which it was reported were very much fewer, the 

 attacks mostly were much less severe, and whilst in 1891 the damage 

 continued to be a serious matter during much of July, and even in 

 some cases up to the middle of August, it is satisfactory to note that 

 in 1892 I had no reports of serious mischief after the 11th of July. 



The methods of prevention and remedy require no further comment, 

 as these were entered on fully in my preceding report, and in the past 

 season it has again been noticed that any treatment to keep up the 

 strength of the crop under attack is especially desirable. 



The Diamond-back Moths are only about two-thirds of an inch 

 across in the spread of the fore wings, and as usually seen in a some- 

 what rubbed condition look like brownish grey moths, paler or darker 

 according to the amount to which the powdery plumage forming the 

 pattern on the wings has been rubbed away. When in perfect order 

 they are easily recognisable by the diamond- shaped pattern formed as 

 figured at p. 138 by the light marking down the edges of the fore 

 wings as they lie together when at rest. The caterpillars are usually 

 of a delicate green ; sometimes in young state yellowish or greyish, 

 with black head. When near full growth the head is usually grey or 

 yellowish, and the next ring is without the two black patches often 

 found in caterpillars of this nature. The segments have some black 

 dots, and the caterpillar tapers slightly towards each end, and at full 

 growth is about half an inch long. 



When full fed the caterpillars spin cocoons in any convenient spot 

 on or near their food plants. These may be a mere open net- work of 

 threads, or thicker, and of a sort of boat-shape, and within these the 

 caterpillar changes to a chrysalis, which, when mature, is (character- 

 istically) whitish, with some black streaks. In their early stage they 

 may be grey or brownish. 



The above note is only given as a general guide to the appearance 

 of the infestation, the details of this and other points of the attack 

 having been so very fully entered on in my ' Eeport of Observations of 

 Injurious Insects for 1891,' pp. 105 to 164. 



