241 



ivaids throujih the skin. Tlieytlicu spin a cofooii cither within the lioh' tliiis toniied 

 jr, more jj^enerally, on the surface of the tnher adjacent to it, or, as is often the ease, 

 )n the sides of the receptacle containinjj; this amongst the other oiitkts, and then 

 immediately transform into the chrysalis phase. Two or three chrysalids may be 

 plated side l)y side. They are always completely covered by particles of " frass" or 

 arth. The fully matured insect, the moth, emerges from the chrysalis shortly after 

 two weeks have elapsed. The union of the sexes ahuost imnu'diately takes i)lace 

 iind another generation of jxttato-dcstroyers arises. The moth is quite a night-tlyiug 

 insect and only lives a tew days. 



The number of cateri>illars which a single ])otat(» may support is very large, and 

 limited only by the anu)unt of food which it yields. Meyrick mentions that (me 

 tuber must have contained quite forty larva-, and we have bred fifty-eight from eight 

 potatoes. "Their voracity, however, is so great au<l their diligence in their vocation 

 so untiring, that a couple of individuals will thoroughly riddle and destroy a i)otato 

 of fair size during their brief but mischievous career." (Berthon.) They continue to 

 feed in the tuber when even this becomes completely rotten, and iu couliuemeut 

 " deposit their eggs on potatoes when these have become not only piitrid but exter- 

 nally shrivelled-u]> lumi)s, whence fresh larvie are ctmstautly being hatched." 

 {Tcppcr.) 



When potatoes are attacked they soon manifest little heaps of earthy substance on 

 their surface, which conceal the chrysalids of the insects or the entrances to the 

 galleries, which section of the tubers discovers. This penetrating their substance 

 causes potatoes alfected to rot and become worthless. We do not know how soon 

 the potatoes are first attacked, but if prior to the culms Ijeing dry, as is highly prob- 

 able, those, too, will no doubt evidence well marked symptoms. 



EXTENT OF RAVAGES OF MOTH. 



According- to Boisduval, as quoted by Meyrick, iu certaiu districts of 

 Algiers duriug" a single season three-fourths of the potato crop was de- 

 stroyed hy this ])est. Otto Tepper thus relates his Adelaide experi- 

 ences : 



As far as my continued observation goes the insect causes now (i. c, iu 1S81), in 

 its immature form of the caterpillar or grub, the destruction of hundreds of tons of 

 potatoes every year by boring them, and thereby inducing putridity. During late 

 years I have scarcely ever Iteen able to get half a dozen ])ounds without finding a 

 considerable percentage nu)re or less affected in this way. 



Again, 



That these nmths occur in otlier situations less confined than the entomologist's 

 hatching case was gleaned latterly from the information a farmer gave me when speak- 

 ing about the subject. He said that he had several bags of ]»otatoes of his own pro- 

 duction, and ([uite healthy when dug, jdaced in his storeroom, where they were left 

 undisturbed for a considerable time. When he at last came to open a bag for use, lo ! 

 quite a swarm of little moths greeted the event, and to his surprise he found the 

 tubers spoiled by the grubs to a great extent. 



APPEARANCE OF THE INSECT IN A:\rERICA. 



The first week in November, 1891, we received from Mr. W. A. Web- 

 ster, of Bakersfleld, Kern County, Cal., two potatoes infested by the larvae 

 of what is without doubt tliis insect. The larva? were working just 

 under the skin of the potato, forming long and narroAv mines and large 

 irregidar blotches, giving tlie tubers a scabby appearance. Tlie larvae 



