The western grass-stem sawfly (Cephus occidentalis Riley and Marlatt)

Material Information

The western grass-stem sawfly (Cephus occidentalis Riley and Marlatt)
Webster, F. M ( Francis Marion ), 1849-1916
Reeves, Geo. I ( George I. ), b. 1879
Place of Publication:
Washington, D.C.
U.S. G.P.O.
Publication Date:

Record Information

Source Institution:
University of Florida
Rights Management:
This item is a work of the U.S. federal government and not subject to copyright pursuant to 17 U.S.C. §105.
Resource Identifier:
29649029 ( ALEPH )
79356914 ( OCLC )

Full Text

CIRCU N 117. I r1 ': 1
IUnited States I)eartimcnt of Ai(rictilture,
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T he western Vi'ra---'lcii i \ > ,tllv t ,^ /'. i't ~-TiJ,, nf,Q '~.... Hi} -. ,+++
M[ll'littl), \ hi' h i li lia cnti-'ed nniticli :i]ilnrin i "il,, i- n'r .---. tni ll lu_-; r,,. ),,
whleat growers (f Northli I)ii ot~ i (ll t in + lit .~c;>(>ll i)l" lt e(tf). i- li()t v
;illy lle lls ai ew insect l l t;.l.l.- "h_-l tlii- i- it- lirwt ;ilii|)I;ilIiin e i lei

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pes t his cireilar hais eii premIared. IThe account of the habits and
easonal history of' tlhe insect. list of food plants. and ldescriptioni of
l)oll larva and adult represent the work of the imanyv observers men-
tiom in til pa ragrapl on hiiitoryv aindl distrilition. a;is do also lthe (los-
ing -tatemlents- as to natural clwcks- iup)hn it- increase. anld preventive

IThle first- observation o(i lihi- in-ect was made by1)v M Ir. Albert
Kocbele." an agent o, llii- police'. who found thie larv.e birurowiii, inl
'ras -stenm, in ('aililornia in 1SM). and whlo rnared tlie adults. Fronit
these andi others whih haid Ifcli collected in Montana and Nevada the
species was desMcilled by IQilev andl Marlat. whIo said: "' Tli eco-
liolnic importance of 11is species asri-e.- from the fact that it may be
expected at any tini to a)iandon iti natural food plant in favor of
the small, grains. on whith it can doubtless smuccessfullyv develop.
Such changes in thle food habits of our native inset's are constantly
o(*lirriing to tlie great detriment of our ai-ricuidtire. as is illustrated
by lie attack of tlie .Vyiu !.s amnd DoiW"',. species on wheat, these
insects nonirmally afl'ect in' wild grasses.-"
Tle fullltill ent of this proplfite sii,-.'.-(i w ':.s not I-i ,_2' dIelay ved.
In IS',. the late ID)r. James Filetclier."' e1t', ill' ,1,;ist to the I)ominion
of Canada. reported that lie had found the adults, which lie be-
lieved were tiose of ( h /,.. p/ygI/.ii mtu L.. tlie Eurol )ieaIn species, at
Indian HIead. Northwest Territories [Saskatcihewan and that Mr.
Joihni \Wennian. otf 'Sonr'is. l:itolba. hllad sent in wheat straws con-
tainling larvae. Mr. Weinman wXrote that lhe damage resuiltint from
this attack was not appi)reciale. In 1902 D)otor Flet cher" found
thle larvae iiiilumerois iln ra-es in the Nortllwest. il 190). 190(1. and
1907 llte junior almthor oservcd thie work of tlie larva- in grasses
tlrnioughout tlie northwestern I nite(d Stat(es. and in 19Mt; found tieit
damainaiing whea at a I ult. N. I)ak. Iln his report for lthe year 19)S
I)octor F chld ier agaiii referred to this insect, stating thal in thie pre-
vious ailiutm it hladl allppearedI in central \! Iliitoba and the south-
eastern lpart of Sasklatclhewan in nmuth more serious nmnlers tlian at
ally previo-s ti inw. 'I'lie broken straws which resulted' t'rout its attacks
were seen' n in many Hi(hls and ll(easione(d some alarmi." Mr. Normani
('riddle" -a l'armner andt caretful olfs-vi or i) n u .-e'L. ,o A.weme.
AManitola. and the inventory of thle orasshopper p)oisMon which bears
Iis namte reI-cog'lized tlhe insect as 0' /,111 ls 04 I )octor Fletcher at the emt of the s-eason that tlihe species hadl inieised

I nsect Iife. V il. 1Il p'. 71. P'-90.
"' Ani. I p. I:\xi. l iarm s C;i- il ;lt fI. IS lit; 22I '. 22' .ll. 1")s4T.
I m I I
1 A1 l. Eel,. Exp. I.17l'11 C, 1;ll f. I907 pp. 1!! 192. 1909,
1r i 1 7 1

COn I dIa erab I d ii n i vli la-(II It v> 'a11 or zw aIn I I I;i( I u ne I II i- attlti loll
to eant Andt r'v>. It I lo :It1;iin oi" l'w it o n it it ,_, : ~ra - i11 the
\\ dillanivilt V all+v itl ()I ^' ol,, ( I l I I I itaI,+ I i r. II It. Il % hni I a l,,h,,xv. o,,f
New York ('iA v. ",riti t" lirom S l",rw ool. N. I);i,<.. l. illot it
"o n (blull l ig'.tig front -, it 'YA" I,'r rcin l *if the ,Itt>a( ill liel Ihll+.
in th, S ,ui- \alhrY, and Mr. 1. V\\. Sharlt ofl' Fl r'o. N. I);Ik..
YC+ u'lP, -.i liln ar depred1ationj- Ki t le' +i r \+;ilh .x+ IZr., ,i'
ud Itlths li \' lhavv hty l'foui l 111 Ml;tiitol>;, llt I);kll.|;, -. Ncllrai-kni. I,;tn -a>
( [irol ;l l)l\+t. Sa>-kwldtticwv', ii. .M (,, It ;I. \\'y\>,vo inirit. (K'ol,, l' t ( )t'hetnu.
Neva';d(la, ;And ( 'l ]iforin;a.
II1 \1;1 l 'l> \ 1 I ) l:\', (> + \ \ 1 l l l ^ l +l +l 1

Ifar ll .M tii ;I. frolntii the I v'oiLll lc. hill' ,rthe-' ;o lat ido -i ii Jv
l':y t inr)- I' ii +., h *iw ll ( t i, .{tt ,1 t. t> \ ) :\\ i trin ' i ri-{+ >l i r \,\t'. ,li>+ .l iil'
""i lht, ]oiI+i ,t l i' h Ia +liclw cfii l.I t,'I *J +l l ; ind tin' trcoii \\,(', cl. i ifh .Inly.
- Ile- Iiarva, O ig". 1, (it }-ooli hakrl and l<' tril Io eat ([(\\] mllide III(,
-tini, Iriiallv yachIi]ni, the' '- oiit d lo\\ard ilir .il ,d' A\ lmi-u, 1oA
whicl i n tin ih(,\,l i atilr,." T'li tha nt ( a111 A hIrizonttal ring, 11 tl
interim- of thvt c near thei < t -tll'frp (da "f t16n 'iind m)o aI iai'- h' to
evetr it. after ,lhii'll the", <'l\ c tls t Il a, itY I, ,low .- "ootl ',v All *,a [>ligii
of' ca: tillng-s :tll a lld Ai thinn. -illvken. v.,dli drical 'o,, mn lbcl<>\\ tll, |)l,
(lit.'. 1. +IIT e e (('i u tally l-to" Ial.v-E (o10' n a1tlv al 1l11 ,1 WI 1v\141 riliA4
dlirii .. i lthte :1i1tilnil lhIIt Inlav 1'1' iiiH Il it pl .-itiln ut i il \w inte "r 11"I
l)o s.ilyl\' I my_. 1. ". III th('> r'e t rm -." l0o, I i)otc t ag 'ain fro m (M r rid
div. "(li, ] m,+ larva- tlw (I +vinit+t tr ial a d '. tii it An ; 'li\k v mo< dlith t
ill(ia +nicd Intil M a+ \ oI' ll l oll, n', iuj year. whenl I II"\ tl, rn to pup,'.
alm! (eniv rgv' a+ per i f t -nwlkis toward tlie ciid olI .1 inn,. tl I' dl;U(' \ ar
ing" -)ncwhat witlh tlec -<>a";)ii." T inp adults ,,, lw-.n Iy l)War In- ( r
li]tctlir.'' -lidv A. oi tl {e fhn r> t esof tiuml)lini a i ui tard,.
Tlhe injiired el tnl A|)p ar), di-color-' d clhvct,, Ila, li< -t And third
joints and tllihe t l ",a mia\" Ile seat) tliirni l the' I nuo-liircnt v, all ol" tlh,
>I, lo di\ Irin H i> wt'attAi tell innest. In (lte 'c's (of ",Ili'at. lh<' -liln rtcNvt
l) dn at tlil, |oiit. An i +ll or tw", 11 l lo ;I Jo)iint r d11vu Wlinii :;d w)o\'
a-, in llc,-ia i fly ityiii "r\. aNd tlic lKc id fall- I" ile Ui'roiind -AIIo l\'*v
lheft .l, lia 'v ct, I)r. ,J. II. ( nr l 'o tol k' i 'onn, tliat tllir l'thatiii,,l0+ ("'H.11
-a' ulov. an anwllied ,-lo v'i K uidl ;, l1'cct Alime A.i/,c n lric tih o wi (d the,+
kIe'riu+1-. lu t it ik W ll known tlhat ,irra"--.. lia t\ lW lrad- 0 2l 111itl I \
("IF -lecif-. And : 1oI'o ...-o.'r P lc IAll,, "Write- tllat tln, Ihe';ad- 44' N\\lirat
;,i'l( 'lirilitl ll (m in a I t ( N, dtlaioi o,'f fi d -ap Atl tl6 .ln ti l tiUHi ,. If" l>n U,'NiNic Nll\ irli'. tlhc daineir' Io ldlr' h (Tp) i~- ItnilHT '' at t lmu
las lIm,+ *'>tin,11 dt'10 l'oiii tlic m lir ol' V';dl "* .\ i+ IS l,. l"'. | +nwt l'n r n i ;& I |y+ I+ vT C',. Q 4| 4 1q, 19 1 Ito. lot i .
"A+nn. l51v+1+ 1 K '.+, l ":+n + Amotk:,I r+ '. ; 1 ++ I n Vol O ,+ M T1
IW L 11 O u,'nf ,ir l 'ni,..\LtI. l+:xi ,. Sin.n N mi+,iiiliil r.+ + -, .
1 ir 1 7

:tale- tlhi inII a field o(, wheat at AwemIne. nI:,itoba. 7.5 per c(ent of the
in fes ed t elins collaplsedl before larvhvta but wve olbs:erved a field at
ililni. N. I)ak.. to liave )Ily ,i ; per cenlt of the injured strl ws 1)roken.
'I'le Inative a'1:s*ie do lot collalpse wheln attacked lY t1ihi insect and it
is p)Os.-ile that .-ome -ti f-stellimmted wXhieats may stand tIII) better tlhan
o'ltuer vzrlietie. iTh is a1 n 1 :a1 a t oe t ho(e L Ifarller iII prevention
total os of tite a:'fected heiadsi but a (lisalvant tagoe if it prevents
linn1 I1'oil de1(t1ectilln, the ca sell4 anId extelit o(f ; serious s:-lrilka"'e of
the. keres.
The' dbiaate las beei confineid iretvl44'f tor t ,mldordel by Ira-. land4s or roadsides. IwMr. riddlele" states that 50
1pr cent of thw stalled in ifeste- for a dtistallce of 100 feet in11to the
fields. and that tlhe dAm:aJeM i- a:ppvlalent to a les-er extent throul'lhol'
lthe crop. lie a]-o( s:lte's that the ill-ect seeks wheat onlv when it
fails to lil el(l oIlouh t1wveril slt'- o1 gLasses(d in which to deposit
its ( .',-. Recent reptlm'l- t'rom1 Noth I)Dakotla indicated that the inIjrIy.
imaX, be more general tha taihewretofove and s ptobaihlv halapted it- h1a:lit-, to con'om4i 1(i to w farme methods of thai
reFgliol so that it io hlo er dl depelds lpn 111m lati\e ,,.i-- buit l)br'ed-
tlimro-hioIll thle fields, at o1ce dislVilbtin hlie d1ma,11e more evenly
:nhd inlc'easin" its c( for hliarm. A pest which can lake adval-
ta:1e 4 wXild food pilalnts and vet 1be ihdep[lilenlit of tllm is far more
dianilerous than o(11e which call feed ohnly upon wheat or one whiich
requires both wheat and a nativXe gra a.
Fo()D P1 LA NTS.
This sawtfly is a nat ive insect which hlias, learned to attack wheat and,
according to Mlr. (Criddle. rye also. since tlhiese ohave taken thlie p)hlce
of its native food planits--quack grass and whieat -rass ( Agrop)yronI,
bron)e 2,-- (Broimus). rye rass (Elym vnils) and tinothyv (Phllehin).
It was es-pecially avbundant in At'rolyron :11oii, railroad embank-
ments in North Dakota in 190W.'111ad 19)0. so that in many 1clumps
of this grass one-hialf of thle leads were p)rematurecly whitened.

Thle larva (fig. 1. a) is ahout throee-fifths of an inchli lon and one-
('ei-hth as wide, slightly larger near tlhe lead. and taperia,_, toward
Ithlie ail. Which ends in a small. 11l. upturned. Ir)1.)wn tulbercle. The
o(ldy is Yelowmisl while: lthe lead. a spot on tlhe bac(k of the neck.
rins o (lithe palpi, tlie tips of( thle paired cerci, ;1. ad the setae oil the
last sei 1mel. are pale fellow: the margin of lithe(, cheeks and of the
aiteleial se-'nelsi, a tfaint streak 4on each cheek tliro'hi the eye, the
m11:n11 )11h-, lthe ti-L1-int 1:. : (lihe mIe(lialn a11,I tutbercle, are iih,,'_.i, v

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wh('!l larell ;, W h- Ni' MI H h4ttN Whi11 SPlOll!l l l a' lI IMS T dinf~lid I \h Vill : o t'n'11

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It lti \ llN l 'i t s 21t lti. lIli a l in p Ii< ; I tLYi ti l I a ina tlils;1\. Anlil liI ]
lll;1 .ill tIl t hl r lh i l. lil'l t tll I''ltlllililt in lll'l S l 'I l Nl l A :ti rtW W h "Ii i i
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Ain. ('idleo found that iianv ofi tIl broken ste i- of illnfeted
x hadl h eilt ill iuch a w; a sv I to crus-h ;and kill the larva which wa-
wIkiini 1"t tiltle i)intl where the steloill collapsed. Since the sten'll of
_ 'IsSC-e-h do iot hr'eak luielv it.' attack. tlti is a danger which'I thie il-
-UN. lhas incur'd Iy chanigliin' to al new food planihtt. Tlii> 'oril of
:a (idenlt matlltr'iall\ redu es the t ltlil elr of indlivitduals \\hli li ianv
'l'acli mat111it11itv :ti and deosit eg',-s ill thle wlhat. -since' fromil C to 70 l|
(elit of the ilnfested steins b'eaik ear tile loint wheeli tie laiva is
\wokinLi'. shoitl Y helloe thle larva r: leteat toward tlie roots to i'e-
parei' for hierliatlion.
Iarasite's werve retired 1 by tilhe junior aluthlor lfrow la oll- e lhted at
Miiot. N. D)ak.. helonl1'inl ) to all uhide'i'-ribed >pecie-' of tlhe 'ialcidid
trilie ':intedoniilli.

ir. ('riddlel tijed huriiliil tlie still>lIie i l e ai tuitlul vith thle aild
of straV scattetel o veri it, hibut foull that thi l:arv \\ve tnot iiuiht
dam|111agred thereby. 'k remedy which u"g'r'ests itself and hias beenl
praltiedt to some CAWxtt is tlhe plowilni down of all stubldeh either in
allltu1mn or before .Jiiine Ii), at which tiiie the adults ilay he expectedl
to eImlee anl d dl po-it eg'-s. (Grans giroi\ i1 ear lthe Alp,' of elidl-
suldt he im toweil early ill vIiv. htile the li a\'e le -mall. to) prevent
helm from lliat 1111r12 and thie crop olf lie ifollow\il12 .Year.

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