The potato tuber worm

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Title:
The potato tuber worm
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Book
Creator:
United States -- Bureau of Entomology and Plant Quarantine. -- Division of Truck Crop and Garden Insect Investigations
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U.S. Department of Agriculture, Bureau of Entomology and Plant Quarantine ( Washington, D.C )
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aleph - 030285433
oclc - 779489551
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Full Text





E-554 '9 1


THE POTATO TUBER WORM


Prepared by the Division of Truck Crop aid Carc
Insect Investigations



The information on the potato tuber worm (moth)
operculella (Zell.)) presented here includes a descrioti ai
stages, its life history, and the plant injury that it causes to 'r
notes on other insects, or their injuries, found on the sa-e hcat

Host Plants

Hosts of the potato tuber worm include potato, tobi j ) ioe
(Datura stramonium L.). eggplant, horsenettle (Solanum o n .
tomato, pepper, and nightshade (S, xantii Gray). Larvae o t pfi
worm feed as leaf miners in all these hosts and a!,so )k at ptCt
tubers and tomato fruits. On tobacco this insect is c>d 1 ',ra

Character of Injury

Injury on potato by the potato tuber worm is of t%-- (J' i
mines the leaves, petioles, and stems of the growing p e-d_
tunnels into the tubers, either in the field or in s '>
may injure one-half to two-thirds of a leaflet in mining, t h o
petioles and stem when partly grown (fig. 1) The part bey( d t fl ii o
feeding in stems or petioles usually die. Tuber-feeding 1nrv III 1 thrg
the potatoes, so filling these tunnels with excrement, o n:.hi 010r
that the potatoes are unsightly and of little food value (fi j va
usually enters the tuber near an eye, covering the sho-l1 enrxi hi~e wt1
a web and excrement, so these holes are inconspicuous A p-I- oo t
developing in the flesh surrounding the entrance and ddito, 1
make the presence of the larvae more evident within a Lo, day. ( e
from 1 to 3 inches in length may be cut by a single 'ac fi t be-
neath the skin or deep in the flesh.


E-554






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I5i'r on tomato foliage is -irilar to that described on potato
foliae, nd the tomato fruits are also attacked. The varieties of tomato
with ji2 solid flesh and growing on pie with sparse, open foliage appear
to beo readily attacked. The lra usually enter the tomato fruits at
the stem end, although occasionally entry is made at other points.

~r'v Co tobacco cCsts prii pally of leaf mining, although the
tuber s a e af. Ordinarily oni h o-ler tobacco leaves are affActed,
unless the infestation is very severe. in these older leaves the leaf mines
take the form of grayish, irregular blotches, which later turn brown and
become 'ragile, so the affected leaves are unfit for use.

Comparison of Potato Tub, i and Tobacco Splitworm


Exper its perfor0med by Mu .rga
staus f te::potato Lue w'orm and

the haitualpotLato-feeding t p. ou
tuber 15 d o lthe foliage or tobacco,

Larve~ o I the obacco splio.u, o
ree i o maturity on Lh sae
potat-ein type, (2) Afml o
with :al of the pow w-fe ing K j
duced ia n that reachedi matriy upon
is 1age ihan the lara fou tobacco,
mesot>) metathurax, vihiie h
gene. 1ole AitL a deep maroon thsa


d Crumbs to determine the specific
1e tobacco splitworm discos the
L e of the potato tibr worm, of
be reared to maturity on potato
eggplant, horsenettle, jisorve V,
ock nightshade (Solanum niru L.)
biual tobacco-feeding type were
plats mentioned for the habitual
htobacco-feeding type, wahen uted
eared from isolated pupae pro-
Cocco. (3) The larva from potto
ray in general color, with pink
Stual tobacco feeder is ree in
,, Lix and metathorax. By reversing


the t a plants Lhelar me t approach each other in color-
atioan ven after 6io g~nei o tobacco the habitual potato feede
i e < and has the 0 thorns di nc paler than the habitual to acco
feeder; o, I,,q~n rearwrd u ~ol par ato t s, the coloration of the latter
fIn e opinion I '' In iators this rather peristent
coloi o in Lh o l i not of sufficient importance
to cilic se-aratio Ao the potato tuber 'orm ree
from po <, < t bers, tobacco, hors jiaesoweed, and ground chr.r, and
jdult i < tobacco spl tw. raard romI tobacco, potato tu s and
ground o' y vure submittd to Augu [ Dsk, of this Bureau, who rpte
thai he could lind no specific die

Desrip i of Stages

Ej Thu egg is tpproximatel ] O, iumi. long (1/50 of an inch)
When !shldeposited it i oque ad i y vhite in color, chaning tO a
yeilowis color as it becomes ohe


e ist of literature consulted






-3-


Larva The larva n 10lI-grown ranges /.'8 o 1/2 .
length and m -y be pink, green. white cr pale iI >
and protioracic shield 3 d ussed in a pr c cd' o,
cular, the species of' food plant eaten by the laL.d i ly La.
upon its color, although ihe achial color of the
sarily influence the color of the larva.

_Pu_: The pupa is approximately 1/3 inc, leagnh nd p P
shaped. It is usually found within a white silken o Then first in" ed
the pupa is white and bears green -,arkings, but i o n'es to i
pale or dark-brown color. The cocoon containing te pup is ua 11 y -
spicuous unless concealed or discolored by dust or dir

Adult: The adult is a small moth, approxiiaIely / o I/. ch
length and with a wing expanse of approximately 1/2 1 a Th e 11 et:,
slightly larger than the iales. The adult has a siP a-. olored (I rd
bears minute black spots on the gray, fringed forev.ia.

Life History and Habits

The adults are weak fliers and when di+tu'"%. :o ield Uin
the day they dart from plant to plant. They are i uch Core ctive heeer,
during the prevalence of the dim light of evening o rca tl.:' morning -h-n dur-
ing periods of bright sunlight Each female deposits f' o 150 to 200 egs
on an average. These eggs are usually deposited oc o.me rough surfe,
cucji as on the lower surface of the leaves of the ho plant adjacent to a
large vein or other rough tissue, or in the eyes o< potato tubers .eft
exposed in the field. During the storage period the egs may b- dep tA iled
on the potato tubers and on the covers of the barrels containing the tues
Whew. the larva reache.- full growth it usually deserts its host-plan

leaf or tuber in preparation for pupation. Tn the i e11d nost of tie r .:re
pupate in 'he soil. In storage they pupate, within O
situations as in and around the eyes of potato tubs ii crevce o -
rels or storage bins, or on builap sacks or barrel coverin.

A generation of the potato tuber worm may be Co e r, ithtn a d
of 13 days in midsulmmer brI hay require as long 2s pi -tely 7 .. 1.
during the cooler period of the year.
_rfestations of tuber ,,ras may build up in z-' 1re cull pc a -

are allowed to remain in the field following the ha g of the priag
crop. Volunteer potato plants and solanaceous ed I serve 's soutoe
of infestation for an outbreak of this insect, espe hialy if a second rep
of potatoes is grown on or near the same field.

The tuber worms gain entrance to the tubers eu h aurlace of In
ground by entering crack in the soil. Tubers cered with at least I
inch of soil are not subject to infestation. Vhen the fubers are exposed
at harvest time they may become infested by la-,iae or egg-laying adults



UBRARY

STATE PLANT BOARD





-4-


tops Th lr>ae ,cDly from the yn: rotato plant
>~cw oeda oe to Lhe tube s


..o i oE 7

%1 o s71rin8 and may even d
77at perod, diependi~n8 upon th


cs uily in potaocs a are not sub-
;n< enily may develop in some areas
? celars, which see as sn ource of
e plants or aie l! planted crop.
(nd market potatoes el in storage
oe b:rough one or -o geerat ions dur-
te:jperature.


TTP I .c 11parety does I ld up to large :trb
~ I~ff( 7 ~1 O~ potato topF, 7
nelop tn 7bers, o. fO is abundant an. ,I
fav orable


2)5s wI*,e it is
greatest popu-
LaIO Lres are


Other Insects
n o _: wo (ifer ] ?iCPI 1oeT0r is) s:y ee countered
tO f Huoer VOFWi 01 h'mOO,[) 1" ae a aoui l/ g, and, at a gace, are a grayish
d thn the largerF r:. colored larvae oX th potato tuber


worm.


;so< Tb __ 1 tue~ 11or nos (0 ..

eg- ~ ,, ,< t iay be ':in!:i g i
-{! i : iirt. e

oa ar, orFs 1 f r ii s 1

m. Ve bhic is not lined with sulS.


I ./a -ytl


o .: < Ib r ,. '12 a }



. . ... . . r- 71 y

T( I ivu .....
t i1 : ]i ) i
- ~vig a papery e~ie1 is .0


I i.I ,

/ I.y .iIt i'


9cwlfl L1ochinella Zell.) nmay be con-
c"-':curs 171 leves of h:ore etle and
'd y tihe chaucoer o1 ijs rine The
: r1 et the o g of the leaf
{ '-a v larvae ay ocr 'in 0n a ine,
'1>ube The po 8I tu rf or lrv
:saly only eie Iarn o 'vs i: ech


* 'Lste eind 0 of tca~ :''i1s o" through
: moy be C'isii g Vis~b ro. Ihe
<>v ~e i Cl c p.,lp and
o. c~nish stripes.

0 o' ihA sides of

]d with coW t ue de to ac-


injured b scb r posts.
'ip fi.ledi with %: j0 ] Le.s of excre-


s~ ki. ',' I 1 L i jur by1 1 1 A s is
1 7o V l'e i.] ii






-5-

Flea beetle larvae feed on the surface or penetrate I/4 inch into the
potato, leaving roughened, pimply scars

Literature consulted

(1) Anderson, L, D. and Walker, H. G 1936 Co W,, (i the potato flea-
beetle, Epitrix cucumeris Harris. Va Truc, Expt Sta. Bull. 92

(2) Essig, E, 0. and Michelbacher. A. E, 1936 liiportnl tomato insects
of California. Calif. Agr. Ext. Service Cir, 99

(3) Graf, J. E 1917. The potato tuber moth. U S. DepL, Agr. Bull. 427.

(4) MacLeod, G. F., and Rawlins, W. A, 1933, Iisect ad other injuries
to potato tubers. Cornell Univ. Agr. Expt, Sta. Bull 569.

(5) Morgan, A. C., and Crumb, S. F, 1914. The tobacco .splitworm- U. S,
Dept. Agr. Bull. 59.

(6) Poos, F W., and Peters, H. S, 1927 The potato tuber worm. Va
Truck Expt. Sta. Bull. 61.

(7) Spencer, H and Strong, W. 0. 1925 The potato tuber worm. Va.
Truck Expt. Sta. Bull. 53.

(8) Underhill, G. W. 1926. Studies on the potato tuber moth during the
winter of 1925-26. Va. Agr. Expt. Sta. Bull, 251,































Figure l.-Typical injury by the potato tuber worm to potato plants,
showing mines in leaves, petioles, and stem. The potato tuber
worm larva begins its mine near the midrib of the leaf, and
usually only one larva occurs in each mine. This mine is not
lined with silk. In contrast, the eggplant leaf miner usually
begins its mine at the outer margin of the leaf and works toward
the midrib. From 1 to 5 eggplant leaf miners may occur in one
mine, and each larva forms a firm, silk-lined tube.


Figure 2.-Potato tuber cut open to show typical injury by the
potato tuber worm. The tunnels made by the larva in the
tuber are filled with excrement. The larva usually enters
the tuber near an eye, covering the small entrance hole with
a web and excrement, so these holes are inconspicuous.





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