17-i Journal oi-' the Uefaktaiem oy Xi^ eil i lti rk.—Xvo . , 195^. 



cocotins arc fiequeiitl y t'ouncl in the eyes of in)tatoes, because ihese 

 torm convenient depressions. Crates, boxes, bins, and l)ags may also 

 l)e plastered \\itli cocoons. In tiie field the pupae are often found just 

 at the surface of the soil. Attei- about ten to twelve days the adult 

 moths leave the j)upal sheatlis. Tin; peiiod if<|uired from the egg" 

 to the adult is commonly fiom U-(S weeks, and iliere aie several genera- 

 tions in a year, the numl)er varying- \\ ith the temperature. 



/loir iiiheis become Infested in the Soil.—'i'he female moths will 

 o\iposit on any exposed potatoes which they may find in a field. They 

 may occasionally reach tubers thiough cracks in the soil, and may 

 ])ossibly reach tubers that are only slightly coA'ered. This, however, 

 accounts for only part of the infestation. It has also been suggested 

 that the larvae l)ore down thro\igh the steins of th(^ plants into the 

 tubers, Imt this has beew shown to be incorre^-t. Most of the infetsta- 

 tion is due to the hid that the larvae lea^e tlie to])s to bnrrow into the 

 soil and thus enter the tulnTs. That the ^\ilting and dying of tlie toi)s 

 cause the larvae to migrate to the soil is shown by the fact that in 

 summer very few larvae do so \intil the tops begin to die. Cold 

 weather also induces the laivae to migrate from the tops before they 

 have begun to wilt. 



Control : Natural Enenties. — ^lany larvae an> attacked by small 

 wasl)-like parasites {Omor()us phthorimaca Cnslinian) which hat(di out 

 fi(UM the cocoons of the moth. 



Confrol: Artlficuil Method-'^. — (1) The larvae do most oi their 

 feeding within the leaf or stem, and <>an therefore be caught with 

 sprays only M'hen they l)ore their way into the leaf or stem. Experi- 

 ment shows that sj)iaying is of little use in the control of the m<»th. 



(2) ^J'he most important control measure is compact hilling, i.e.. 

 keeping the potatoes well ridged ami covered with soil after the 

 blossoming period. ]\\ thus increasing the depth ot soil through 

 which the lar\ae must burrow to get at the potatoes, many fail to 

 accomplish their object. The correct time for hilling is just after the 

 blossoming period, or in the case of late potatoes before the weather 

 becomes very cold. 



(o) Badly infested i)otatoes should not be used as seed, but should 

 be destroyed or fed to i»igs or sheej). 



(4) Prepare the soil well before i)lunting, antl plant the potatoes 

 fairly deep, at least four inches. 



(5) Do not leave dug potatoes exposed in the held overnight. If 

 they cannot be bagged innnediately cover them well with a sailcloth. 

 Unmarketable potatoes (small and badly infested ones) should all be 

 gathered up and fed to pigs or sheep. 



(G) Sort out infested tubers, and store the remainder in a cool 

 room which is well ventilated and screened, ii possible, so that moths 

 hom outside sources are unable to gain access to the uninfested 

 potatoes. 



Literature.— "The Potato Tuber Moth," by AV. F. Schlupp, 

 Ikdl. 4, 1917, Fnion T)ei)artment of Agriculture;'" The Potato Tulier 

 Moth and its Control," l>v W. ^looie. Union Journal of Aoriculture, 

 March 1912. 



