58 



A small quantity of potatoes (about i cwt.) liaving been 

 purchased on October 10, 1880, apparently of that year's 

 growth, and healthy looking, it was noticed on close scrutiny 

 that several tubers presented to the touch and sight the minute 

 ominous roughness and blackish spots. In a week or two a 

 large proportion was found to be full of small grubs, and the 

 last few had to be thrown away as utterly unfit for food. On 

 the 27th November four small tubers were taken at random 

 from this refuse — all affected tubers having been carefully 

 removed from the stock as soon as noticed — and enclosed in a 

 box with a glass lid, allowing free circulation of air, yet pre- 

 venting escape of any but very small insects indeed. They 

 were inspected at least twice daily, and on the morning of 

 December 4 the first caterpillars were noticed to have attained 

 maturity, thus requiring a minimum period of about forty-five 

 to forty-eight days for their development. The caterpillar is 

 then about half an inch in length — rather more than less — and 

 not one-tenth inch diameter in its thickest part, viz., near the 

 middle, whence it tapers both ways. The posterior extremity 

 ends in a point, and the whole body presents eleven isegments. 

 The head is dusky, with strong, black mandibles ; the re- 

 mainder is of a dirty greenish-grey above. Most, or all, of the 

 segments are marked with a very faint narrow pink transverse 

 bar ; the underside is faint pinkish-grey. Having quitted their 

 galleries, they spun themselves immediately a kind of cocoon 

 formed in the angles of the box. The dirty-grey silk forms a 

 slanting roof over the chrysalis, is very closely and firmly woven, 

 and about half an inch long by one-eighth wide. Each one 

 forms a separate cover, but many may join like the links of a 

 chain endwise. The chrysalis is very small, and scarcely differs, 

 if at all, from that of other Tinea dee. 



On the 22nd December the first imago presented itself, and 

 next day five more appeared ; thus about sixteen to seventeen 

 days are required for this stage. In the meantime fresh cocoons 

 continued to be found almost daily, and since the first appear- 

 ance of the moths, their production continued with such 

 frequency that at the end of January, 1881, several scores had 

 been obtained. This may be explained by the fact that those 

 left in the box paired and deposited their eggs in the now 

 putrid externally shrivelled and dry lumps, whence fresh larva> 

 are constantly being hatched; and this, it seems, continues 

 as long as they find the least moisture within. This fact proves 

 that the insect thrives not only in fresh, but also in putrid 

 tubers, and that therefere any refuse heaps of them, left unde- 

 stroyed, act as a hotbed of propagation. 



The moth is very insignificant in size, and a strict nightflyer. 

 Although great numbers must exist, to judge by the ravages 



