DIAMOND-BACK MOTfi. l39 



Eeplies to inquiries in circular (see p. 110), August lltli : — 



(1). "Evidences of the ravages of the caterpillar may be seen at 

 least six miles inland, and I should estimate that from a third to a 

 half of the crop has been destroyed. Eesowing has been attempted in 

 many cases, but it is yet too soon to say what the result may be. On 

 Saturday I observed a second brood of the moth, but in numbers not 

 nearly so numerous as on the first occasion. 



(2). " Soot and nitrate of soda have both been freely used (near 

 St. Andrews, Fifeshire) in this district, but I am doubtful if either 

 had much effect upon the caterpillar. The remedy was attempted too 

 late ; in fact, just at the time the caterpillar was spinning its cocoon. 

 It was beneficial, however, in a secondary manner, as it would push 

 the plant into more vigorous growth. In other cases scufilers with 

 boughs were sent through the fields. 



(3). " We were certainly fortunate at the time the attack was worst 

 in having heavy rains, or otherwise I believe the result would have 

 been even more disastrous. 



(4). "In some cases whole fields were destroyed; in other cases 

 portions of a field seemed to escape with comparatively little damage. 



" On inquiry into the reason of this, it was at once apparent that 

 it depended to a large extent on the nature and condition of the soil, 

 and the state of plant-growth at which the attack had commenced. 



" Early-sown Turnips in good soil, both as regards mechanical and 

 manurial condition, survived the attack and continued to grow, while 

 on hard clay soils, and on back lying soils trending to the north, and 

 where the attack had commenced shortly after or during thinning, the 

 plants were entii'ely eaten up. 



" There is no doubt that the best preventive is to have the land in 

 high-class condition. In a field, for example, which was well done to, 

 a portion which got an extra dressing, from the more vigorous growth 

 of the plant, seemed almost to have escaped. 



(5 and 6). " So far as I have observed, there was nothing excep- 

 tional in the weather during the autumn to account for the visitation ; 

 nor have I heard of any particular weed unusually noticeable. It 

 ought, however, to be noted that the attack has been found to extend 

 to all members of the Crucifer^ (excepting Cress),* including Brussel 

 Sprouts, CauHflower, Eaddish, Wallflower, Charlock, &c., so that there 

 is ample opportunity for the perpetuation of the species during the 

 winter. 



(7). " I have no doubt but that the Starling and the Sparrow have 



* Cress also is liable to infestation. I had specimens of Cress plants, which 

 had been left for seed, sent to me from near Kelvedon, Essex, with cocoons on them 

 then containing spun-up caterpillars or chrysalids of the Diamond-backs, from 

 which the moths presently developed. 



