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BibliotMqiM
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Dominion of Canada

DEPARTMENT OF AGRICULTURE

ENTOMOLOGICAL BRANCH

f. (ioRDuN Hiwirr, Dominion Kntuiiolouiht.

THE CONTROL OF CUTWORMS

IN THE

PRAIRIE PROVINCES

E. H. STRICKLAND, M.Sc.

Field Officer.

CIRCULAR No. 6

I ubIisNd by direction of Hon. MARTIN BURRELL, Minister o.' Agriculture,

Ottawa, Ont.

89386—1

OTTAWA

GOVERNMENT PRINTING BUREAU

1916

'43t\**

■

NOTE.

All inquirira rclaling to inwet prats, and papkacra (up to It nunrea in wpi(ht) rnntainins specimens
may be mailed "Free" i( addrrsaed to the Dominion Entomologist, Department of Asrirvlture, Ottawa.

In all rases where it is possible, living specimens of the insects should be sent enclosed in a strong
wooden or tin box to prevent damage in transit. Living inserts should Ik( supplied with a liberal quantity
of their food plant, and in all rases they should be rarcfully parked.

The name and address of the sender should be written on the outside of the package, and a letter
giving as full details as possible should in all cases accompany the insects sent in for report.

Fanners in the prairie provinces may communicate with either of the following Field Officers: Mr. E.
H. Strickland, Dominion Entomological Laboratory, Lethbridgc, .\lberta, or Mr. Norman ('riddle,
Dominion Entoii.jlogical Laboratory, Treesbank, Manitoba, regarding insect injuries, particularly in
eases of emergency. Letters and packages to these officers must bear postage and cannot be mailed free.

Ottawa, Dcci'mImt 1, I'.U').

I ■

To the Honourable

The MiniMter of Agriculture,
Ottawa.

Sir,— I have the honour to submit for your approval EntomoloKicul < 'ircular
No. 6, entitled "The Control of Cutworms in the Prairie Provinces," which has
been written by Mr. E. H. Strickland, Field Officer in charxe of the Entomolo-
gical Laboratory at Lethbridge, Alljerta.

Owing to the serioux outbreak of Cutworms in southern Alberta in 1912,
when upwards of 35,000 acres of grain were destroye<l in one district, it was
decided to investigate the species of C'utwornis responsible for the dainuge and
the most satisfactory methcMls of control under western conditions. Mr.
Strickland has been stationed at our Entomological Laboratory at Lethbriilge,
Alta., since 1913 ami during the past three seasons he has niude a careful study
of all the commoner species of Cutwornjs and has carried out extensive experi-
ments on their control. Our thanks are due to Mr. W. H. Fairfield, Superin-
tendent of the Dominion Experimental Station at Lethbridge, where our Lalwra-
tory is situated, for his co-operation and assistance at all times.

In order to make the results of Mr. Strickland's work immediately u- .d con-
veniently accessible to the farmers of the prairie provinces it is considered
preferable to publish a brief circular setting forth the habits and the main
results of the investigations on control measures. It has Ijeen found that
under the drier conditions met with in certain of the prairie districts, particu-
larly in southern Alberta, modifications in the usual poisoned baits are necessary.

It is most important that farmers and market gardeners should keep their

•ips under closer supervision than is usually the custom, with a view to detecting

!. ns of Cutworms or other insect injury in the early stages. Such constant.

'gilance would frequently result in the prevention of serious financial losses by

idering possible the adoption of control measures before the damage ha»l

assumed extensive proportions.

I have the honour to be.
Sir,
Your obedient servant,

C. GORDON HEWITT,

Dominion Entomologist.

THE CONTROL OF CUTWORMS IN THfi
PRAIRIE PROVINCES.

By E. H. Strickland, Field OiBcer for Alberta, Lethbridge, Alberta.

Cutwomw conititute the most deatruotive inaecta with which the farmera
in the Prairie Province have to contend. Two apecioa are apecially important,
namely, The Red>backed Cutworm {Suxmt oehrogatter) and the Pale Western
Cutworm (Porotagrntit orthogonia). A third apeolefl known aa the Army Cut-
worm (ChoriMOfroatit auxiliaru) occura lesa frequently, though in / ' greater
numbers locally. On account of its apvoialiaed habits it calls foi dlfTprent
treatment from that employed for other cutworms and it is not included in this
circular.

Fio. I.— Full grown Red-baekrd Cutworm; twice natural i<i<. . (Original)

Fio. a.— Full grown Pale Weatern Cutworm; twice natural liie. (Original).
OENERAL UrB-H^lTORY OF CUTWORMS.

The eggs from which cutworms hatch are laid by a moth, or, as it is
commonly called, a "miller," in August and September. TLtse of the prairie
inhabiting species have been found in or on the soil. Most of them remain
unhatched through the winter though a few hatch before the ground freezes up,
and the young caterpillars begin to feed in the fall. These remain inactive under-
ground through the winter and resume feeding as soon as the frost is out of the
soil in the sprint;. The majority of eggs, however, do not hatch until the middle
of April, by which date much of the spring sown crop is above ground. From

Fut. 3.— Cutworm moths: a. Red-backed; 6, Pale Weatern; natural aiie. (After Gibson).

then on to the middle of June the cutworms feed extensively upon all classes of
crops, a nd many weeds. By the latter date, in normal seasons, all are mature
and have formed small oval cells in the earth within which they remain for a
period ranging from a few days to about a month before turning to a brown
pupa from which, at the end of another month the moth hatches. These
moths fl y almost exclusively at night time and must not be confused with the
small moths which occasionally swarm on the prairie by day.

I

«i

HASira or CUTWORMM.

Both of the injurious true Cutworm* of the Prairie Province* remain iwlow
ground during the (ii>y, coming near or to the aurface at night in order to
•earch for fo<xl. They rarolv feed while on the aurface, but !)urrow into the aoil
near a plant to bite through the Ktem below ground, tiometimes thoy continue
to feed on the plant and draw it down for a comiiderable distance into the xoil.
When the Moil i» v»Ty tlry, liowever, they more frequently aimply bite through
the Htem Ih-Iow ground and paw 'm to the next plant, whioh is similarly <lnstroyed.
This habit accounts largely for the fact that cutworm* dn mor« damai., • in dry
than in wet years. In wet soil the cutworms are able to movi- less freely lielow
ground ami come to ,ho surface more extensively. At such times they feed
more freely aliove grou;.d. Since, however, the prairie is very dry as a rule
during the cutworm period, they feed upon the surface to a very much less
extent than they do m regions where the rainfall is greater. For this reason

Fia. 4.— Fall wheat, after rammer fallow, deatroyed by Pale Western Cutworm, ihowinc cliaractcriitia
damage to a ulightly elevated spot. (Original).

control measures practical elsewhere are largely a failure vhen applied to prairie
conditions, and the modifications given below are necessary for successful control
with poisoned baits.

Cutworms avoid moist or hard sc.il when possible and are found in the
largest numbers in the driest and most dusty or sandy parts of a field, where they
can move freely -ust below the surface. For this reason they are usually most
numerous early i the season upon the higher parts of a field where the soil
dries out more rapidly in the spring. Later, they become much more scattered
and may be present in sr vll nurabers throughout the entire field.

None of the usual p.airie crops is immune from cutworm attaclc, for they
feed freely upon grain, flax, roots and alfalfa, as well as upon all kinds of vege-
table crops. The presence of cutworms in a field is not due to the crop that is
being grown, but to the treatment of the field during the previous year.

HABin or THB MOTH*.

The motha fly from th« mlddla of July to the middle of September.
Throuflioiit Auguet «ad tUI »bout the aoth of Heptember th<>y «re Uyins the
*r I from whieh will hateh the next eeMon'i eutwomw. The looktiona eeiee^fd
for eg|>l«yiiig are almoet exdurively tM«fy tummtr fnUowa, p»rtioul«rly thnee
with • rough lurfMe. The moths hide under the elods by day, but umially
will not lay their en in, or on, the soil at a distance from grp«n growth; ao
that even a rough faJTow field on whioh there ie no green growth whatever during
August and 8^>tember is fairly safe from cutworm attarks in the following
year. Clean stubble land is rarely ohoaen by the moths for egg-laying and when
cutworms appear in such fields the fdlowing year they have usually migrated
in from a nMghbouring field where weeds were allowed to grow. A field of whieh
the surface is not broken and therefore does not offer shelter for moths, even

Fio. S.— Flai loilowiBC ■ummer fallow dcitroyed by Red-baoked ('utworm, ihowing mbwqimit
■rowth <)( weed* which attract moth* lor eaf-layioK. (Original).

though it be very weedy, is in lees danger than is a rouch summer fallow upon
which a small growth of wePkis "■ -I volunteer grain has been allowed to remain
during the egg-laying period.

CONTROL MEASURES.

Attention to fallow land. — Crops following summer fallow are always most
liabL to cutworm attacks. The reasons for this are given above, and a consid-
eration of them will at once suggest measures which will render fallow land less
attractive to cutworm moths for egg-laying.

Summer fallow must be kept absoltUely free from all green growth between
August Ist and September 20th and should be worked as finely as is consistent
with good cultural practices.

Dote of towina fa'J wktat.—^net fkll whrat U attr»etiv» to the moihti for
cgg-Uying U •hould not be sown earlier than the iieeond week in September in
order that It will not be above ground before the moth* itiiiappear.

FM ploughiHg.—lMttA which ha* )>*^n allowint t« grow up to wmU, and
weedy atubbie land, vhould lie ploughc' ' in deeply a* ptwnible in the fall, fur on
■ueh land numeroua eggs are depoaitid, and if well ploughed thetw eggs ar«
buried ao deeply that many of the cutwomu hatching from them die fn>ni Ntar-
vaUon before thev reach the Murface. Thia method of deiitructiiin in not, however,
very certain, though if the field be harrowed or packed aft«>r ploughing iu
eflloaoy ii incrr Met!.

PoiaoNiNo WITH BAITB.— For field flontrol under prairie conditions, it »
■eldom practical to spread poiaoned bi i over large areas on accnunt of the
expense of such an operation. Poisoning is, however, always a valuable and
profitable method of controlling cutworms in market gardens and when properly
emplityml c«n be used successfully in grain fields.

It has l)een stated that cutworms are most destructive to crops follow i^
summer fallow, iind that it is from spots, which for some reason, such a ' t
being higher than the ground-level of the field, are drier than the ret. ».. t
general infection spreatk. Much places should be watched from time to .. .a
the spring. If during the latter part of April or in May any signs of cutworm
damage are seen o them they should be treated immediately with the bait
described below, i.i .der that the young caterpillar may l)e killed »)efore they
have become scattered throughout the whole field. In this way the damage to
many acres may Ik? considerably lessened by treating a comparatively small area.
Famers who delay treatment until these centres of infestation are nearly or

Siite stripped may find that the infestation has become too general to warrant
e expense of poisoning.

The poiaoned bait.—\» a result of numerous experiments that we have
carried out it has l)een found that the most reliable poisoned bait mixture for
prairie conditions is the following: —

Shorts 50 lbs-
Paris green I lb.

Mola88<« 1 gallon.

Water IH gallons.

Shorts are preferable to bran for dry farminj^ eonditjons, because no bait can be
kept moist when applied to the soil, anu ci!*« orras will eat dry shorts when they
refuse dry bran. In damp localities and ^«»asonp when the soil is moist the
shorts can be replaced with ar ii, :al weigh* ..f biaa in which case three gallons
of water should be used instep ' ' \\i gallo;:8. In all cases, however, shorts
give somewhat better results than bran. Crude beet molasaes* give the best
results. It is suggested that arrangements be made with a storekeeper at each
town in infested districts to keep a barrel ot this extremely cheap and valuable
material on hand.

Preparahon.— Thoroughly mix the shorts and Paris green while dry. Care
must be taken not to allow more of the Paris green Hust to b.- breathed than is
absolutely unavoidable, when making this mixture, for it is a violent poison. A
handkerchief tied over the mouth will lessen any danger from this source.

Stir the molasses into the water and add the solution slowly to the shorts
and Paris green, thoroughly mixing with the hands all the time to prevent lumps
forming.

AppWcotion.— Apply to infested areas and for a few feet beyond at the rate
of 50 pounds of shorts per acre, preferably 'n the late afternoon.

Thii material can be obtained Irom beet wear miUi wch as the Raymond 8u«ar Milla, Raymond,
AlberU.

8

When the soil is very dry it is essential that the ground be lightly harrowed
after the bait has been applied, for, as pointed out earlier, the cutworms feed
almost exclusively below ground under these conditions, and a surface applica-
tion of poisoned bait is nearly all wasted.

Harrowing is not necessary when the soil is moist.

Reaomng fielda after cutworm devastation. —iio definite date can be given as
to when it is safe to re-sow a field which has been destroyed by cutworms on
account of the annual variations in season. During the past three years the
date has varied from June 18th to June 28th, but farmers who desire to re-sow
fields and wish for advice upon the subject are advised to send specimens of
the average sized cutworms to either of the Dominion Entomological Labora-
tones at Treesbank, Manitoba, or at Lethbridge, Alberta, in order that they
may receive information as to the approximate date when re-sowfaig will be safe
in their district.

-«»■'

CONTROL MEASURES NOT SUITABLE TO OUR PRAIRIE CONDITIONS.

Farmers are sometimes confused by the variety of methods recommended
for the control of cutworms. While a ceertain measure mav be effectual iu one
region it may fail completely in another. In the course of our investigations we
expenmentel with all kinds of methods of control, including baits, and in order
that farmers may avoid unnecessary expense and disappointment we will
indicate a number of control measures which are sometimes advocated but which
we cannot recommend.

Light traps in the field.— A method of control, which has been occasionally
recommended for cutworms consists of placing light traps in the field in order to
catch the moths. Experiments with various light traps carried out by Mr.
Norman Griddle in Manitoba and by the writer in Alberta have shown that
such lanterns attract the moths of destructive cutworms in extremely small
numbers and are absolutely valueless under prairie conditions as a means of
control.

Lime and Salt.— The applications of these substances to fields for the destruc-
tion of cutworms has not been found to have any beneficial results.

Fruit juice added to baits.— Though this is apparently a valuable material
when added to grasshopper baits, it has not proved to be of appreciable value
when utilized for the control of prairie inhabiting cutworms.

Sugar and Salt added to baits. — Both of these substances are inferior to
molaases as attractive agents and their use cannot be recommended in poisoned
bait for application to dry soil when molasses are available.

Stubble burning in the FaH.— Cutworm eggs are rarely found in clean stubble
land, whereas when a cropped field is ?o weedy that cutworm moths are attracted
for egg-laymg it is difficult to obtain a good burn. It is not advisable to burn
over clean stubble land in the fall if the stubble will be of value for catching
snow during the winter.