The Rosy Rustic. 8i 



POTATO TESTS. 



The Rosy Rustic {Hydrcecia micacea) attacking 



Potatoes. 



Amongst the numerous enemies from wliich the potato crop 

 suffered during 1902 were the larvae of one of the noctuid moths 

 known as the Eosy Rustic {Hydrcecia micacea). This attack was 

 reported to the Board of Agriculture from two localities, namely from 

 "Winton, ]\Ianchester, and from near Wigan, Lancashire, and w^as also 

 observed personally. The two notes sent with these larviie were as 

 follows : — 



(1) Enclosed are grubs that have attacked and are destroying a large 

 patch of potatoes ; \y\\\ you kindly say what they are and what remedy I 

 can take. 



(2) I herewith send two insects that I have found amongst my 

 potatoes. They were looking well to about a week ago. Any information 

 about them will be thankfully received. 



In both cases the caterpillars were found to be working in a 

 similar way, namely, by tunnelling up the stalks of the potatoes, 

 completely hollowing them out and so killing the haulm. Should 

 this pest become very numerous it would be a serious matter, as 

 remedies are quite out of the question save hand-picking the 

 attacked haulm. These caterpillars are recorded as feeding in the 

 stems of equisetums, docks, valerian, but probably attack a variety 

 of other plants. 



The larva when mature varies from an inch and a quarter to an 

 inch and a half in length. The back and sides are dull purplish- 

 brown, paler on the first three segments and where the segments 

 join, the sides and venter are of a dull flesh coloirr, the legs pale and 

 the head yellowish-brown ; on the second segment is a brown semi- 

 circular plate broadly margined in front with blackish-brown and a 

 shiny yellowish-brown patch on the anal segment with a posterior 

 border of small dark warts ; on the segments are small dark-ljrown 

 tubercular warts each with a fine terminal hair ; the spiracles are 

 deep brown and the prolegs pale with black extremities. 



Before pupation the larva becomes a paler dull smoky flesh 

 colour all over, with a dusky median dorsal line. The full-fed stage 

 is reached from the beginning to the end of July. During the whole 

 of its life the larva burrows up the haulm and emits a great quantity 

 of green frass ; a round exit hole is made in the stem, the frass being 



G 



