380 The Diamond-hack Moth. By George Bolam. 



being abundant in many parts of Europe, and injurious even in Cape 

 Colony,* and perhaps also in New Zealand and Tasmania.t StaintouX says 

 fb is " always common and sometimes very abundant among cabbages and 

 other cruciferous plants, the perfect insect appearing in May and August, 

 and the larvaj in June, July, and September." While Curtis§ tells us that 

 according to M. Duponchel (Godart's Lepidopteres de France, vol. viii., p. 

 214) it " is spiead all over Europe, and has two generations in a year; the 

 one appears in June, and the other at the end of September," and he adds 

 that "in this country there seems to be a succcession of broods from mid- 

 summer till the approach of winter, for I have taken specimens in the 

 gardens near London in the end of June, at Dover in July, Scotland in 

 August, and frequently amongst turnips, in September and October, in 

 Suffolk and Essex." 



Why Plutella cruciferarum should in some seasons increase in the extra- 

 ordinary way in which it did last year, or whence come the inordinate 

 numbers of the moths which suddenly appear amongst us, is a subject 

 which has been much speculated upon by Entomologists, but 

 regarding which no satisfactory solution seems to have been arrived at. A 

 review of the previous visitations, so far as they effected agriculturists, is 

 given by Miss Ormerod in the paper already referred to, and much in- 

 teresting information upon the whole subject will therein be foand. 

 Curtis alludes at length to a bad attack upon turnips, in August 1837, at 

 Petersfield, in Hants, remarking that he had little doubt that it was the 

 same caterpillar which did hai'm to the crops of Mr Dalgavings, of Forfar- 

 shire, in 1826, and this would appear to be the first regularly recorded 

 appearance of the Insect in numbers sufficient to cause serious damage. 

 Staintun, writing of the moth, says : " In the year 1851 it was excessively 

 abundant throughout the country, and from Southend in Essex, to Belfast, 

 the same enormous multiplication of the species was observed ; the turnip 

 growers thought some new blight had fallen upon their crops, but for- 

 tunately subsequent years have not shown a continuance of the inordinate 

 numbers of this species, which was probably checked by a timely increase 

 of its parasitic foes." In 1863, and again in 1882, the caterpillars are 

 noticed as being abundant in our district and doing some harm ;|| and Miss 

 Ormerod mentions that in 1883 and 1884 she had reports that they were 

 unduly numerous in Yorkshire and some of the Eastern counties. 



The theory that the moths, which caused the damage last year, had 

 immigrated to our shores, seemed to receive some support from a statement 

 published in the Newcastle Daily Journal, and quoted far and wide, to the 



* Miss Ormerod's report in "Journal of Royal Agricultural Society," 

 third series, vol. ii., part iii., p. 599. 



t J. Arkle — " Entomologist," for November 1891, vol. xxiv., p. 256, et seq. 

 X "Insecta Britannica," I.e., p. 68. 

 § " Farm Insects," p. 86. 

 II MS. Notes of Dr Hardy. 



