84 POTATO. [1900 



two very sJwrt stout spines " (vol. ii. of 'British Butterflies and Moths,' 

 Ray Society, 188G. p. 108). 



The common food of the caterpillar is Potato leaves, but sometimes 

 it eats leafage of the jasmine, and also (although I have not myself 

 observed this) it is said at times to feed on the small-flowered shrub 

 sometimes found in cottage gardens, scientifically Lijcium barbarum. 



Prevention and Remedies. — With regard to this species remedial 

 measures lie very conveniently for us in our common field or garden 

 operations in raising the Potato crop, ot the same time so disturbing 

 the operations of the caterpillar in burying itself, or, later on, throwing 

 out the great chrysalis from its hollowedout pupal cell, more than 

 half a foot deep beneath the surface of the ground, that thus develop- 

 ment to moth state of a large proportion of the infestation is prevented. 

 If the caterpillar is disturbed when it is losing power to make its 

 requisite shelter, or the chrysalis is thrown out on the surface, the 

 requisite conditions to development cannot be carried out, and I believe 

 that it is to this simple point of the thorough disturbance of Potato 

 land which takes place in raising the crop that we owe being usually 

 free from anything but a slight amount of presence of this infestation. 



The caterpillar feeds in the evening or at night, and in case any 

 damage worth attending to is found to be occurring to the leafage, it 

 would be well to have examination made at difterent times to find 

 exactly when these grubs are out at feed, and also whether they are 

 buried in the day-time, where they can be got at, just below the surface 

 of the ground. From their great size they are very noticeable, and in 

 twilight or moonlight they might be fairly easily got rid of by hand- 

 picking. 



Gamma or Silver Y-Moth. Plusia (/ammo, Linn. 



For figure of Silver Y-Moth in different stages, and account of 

 attack to Potato leafage near Holbeach, Lincolnshire, see pp. 53-58. 

 Observations of the outbreak of the caterpillar on Potato, and also on 

 Mustard, along the shore of the Humber, were sent me so precisely at 

 the same time, and with so much co-incident in the circumstances, 

 that it seemed best to notice them together, with references in each 

 case to the other entry. 



