BULLETIN No, 129. AUGUST, 1904+

ALABA MLA.

Agricultural Experiment Statio

Alabama Polytechnic Institute.

AUB URN.

The lYlexicall Cottoll Boll Weevi

EDWIN MEAD WILCOX, Ph. D. (Harvard).

Plant Physiologist and Pathologist.

MONTGOMERY, ALA..

I SH; BROWN PRINTING CO., PRINTERS AND BINDERS.

1904.

COMMITTEE OF TRUSTEES ON EXPERIMENT STATION.

J. M. CARMICHAEL................................Montgomery.T. D. SkM!FORD..............................................Opelika.

W. C. DAVIS..........................................Jasper.

STATION COUNCIL.

C. C. THACH ........................................ President.

J. F. DUGGAR ........................... Director and Agriculturist.

B. B. Ross...........................Chemist and State Chemist.

C. A. CARY.......................................Veterinarian.

E. M. WILCOX...................Plant Physiologist and Pathologist.

R. }a. MACKINTOSHi............ Horticulturist and State Horticulturist.

J. T. ANDERSON.. Chemist in Charge of Soil and Crop Investigations.

ASSISTANTS.

C. L. HARE....................................First Assistant Chemist.

T. BRAGG................................. Second Assistant Chemist.

C. M. FLOYD................................ Superintendent of Farm.

I. S. MCADORY....................... Assistant in Veterinary Science.

N. C. REW........................ Assistant in Animal Industry.

...................... Assistant in Horticulture.

The Bulletins of this Station will be sent free to any citizen ofthe State on application to the Agricultural Experiment Station,Auburn, Alabama.

*To be filled.

THE MEXICAN COTTON BOLL-WEEVIL,

By EDWIN MEAD WILCOX.

introd uction..

In twenty years the Mexican cotton boll-weevil (An-thonom us grandis Boh.) has developed from a ratherobscure species to one of supreme importance with res-pect to the production of the world's supply of cotton.The infested regions are taking desperate measures todestroy the pest or to adjust and modify the presentmethods of cultivation in such manner that cotton maystill be grown at a fair profit in the infested regions.The recent appropriation of$250,000.00 by the Congressof the L1nited States for the exhaustive study of the boll-weevil problem from all points of view has given to theboll-weevil a. national importance.

It seems desirable to present to Alabama cottongrowers our present information upon this very impor-tant slbject together with the suggested methods ofcontrolling the boll-weevil should it ever becomne estab-lished \within the borders of our State,: This bulletinnmay therefore be said to result from an application ofthe old adage, "forewarned is f orearmed." No claimfor originality is made as to the facts stated, but thereader is referred to the papers mentioned in the Biblio-graphy at the close of the bulletin for the most recentoriginal investigations of this subject. The facts givenin the papers cited have been freely drawn upon in thepreparation of this bulletin.

INTRODUCTION AND PRESENT DISTRIBUTION 01? THE BOLLWEEVIL.

The boll-weevil probably crossed the IRio Grande riverinto Texas about 1.892--at least that is the opin ion of the

0J2

planters in tha reion. Q !S91 it hadl spr)eadt to a half(iozeni coii niie, in >oH i hll Tcx;c, hor)ei) Upon1101 thePio (iranje river mnO the t Tiilf of 1lexico. At this~ timeit was bro Wil to lie attll I i of thle 1LitIedl States De-partmlent of Agricuilt ure; the D ivisioni of I')tol1-

ogy commliened% latie do liiig 189 -1 tlie inveest igationi ofthu weevil and has umo iniIC( this inivestigation to the])leselit timhe. flT I 1(1 l~ir[neW of ti' L ini. of tile

T~exas lEXperiie1t atatio let aislso 1lelieril eflijiuilt

aidl iln the i11\ (si t 01. 'iulB !-(clut ap ))1'IJ1iat ion byCon-rjess 1has UIiId(I it .l1( to (titelh I le u pont the

boll-1w eevil tiro h iIh the fitN of'I a; lame II 11ii1)1 of1 per-sons and thle w til is mm- IW lee' nii IwOe at tenl io01 than

prlobaly anyv ot her inecet pes~t ini the worttld.

I

the boll wcc, il at interv als since its fiast app))?arance in Texas.

93

The map shown as Fig. I presents graphically thepresent known distribution of the weevil as well as theadvance it has made over the area indicated since its firstappearance in 1892. From a study of the insect's meansof reaching new territory it has been estimated thatthe weevil will be at work throughout the entire cottonbelt of the South in 15 to 18 years. In Texas duringthe past ten years the weevil has made an annual ad-vance of about 50 miles.

Having this danger in mind and to prevent the ac-cidental or intentional introduction of the pest into theState the last Legislature passed the following law,which is here quoted in full:

An act to prevent and prohibit the importation ofseed from cotton affected with Texas boll weevil.

SECTION 1.-Be it enacted by the Legislature of Ala-bama, That no person shall import or bring into theState of Alabama any seed from any cotton affected withwhat is known as the Texas boll weevil, nor the seedfrom any place where the cotton has been affected withsaid boll weevil.

SEC. 2.-Any person who violates the provisions ofSection 1 of this act shall be guilty of a misdemeanor,and, on conviction, shall be fined not less than ten dol-lars ($10.00) and not more than five hundred dollars($500.00). [H. 877. No. 559. Approved Oct. 6, 1903.]

Legislation can, after all, however, do nothing more inthis case than build up public sentiment and arouse inter-terest in the weevil problem and if cotton planters permitthe weevil to become established in this State it will bethe result of their own neglect. Planters and others willconfer a great benefit upon themselves and upon theState by promptly reporting and sending specimens ofany suspected boll-weevil to the Alabama ExperimentStation. All such insects should be killed with chloro-form or other means before being forwarded throughthe mails and then be enclosed in tin or wooden boxes.

94

AMOUNT OF DAMAGE DUE TO BOLL-WEEVIL.

There is frequently a tendency to greatly exaggeratecrop losses, but a very conservative estimate shows thatthe damage done by boll-weevil in Texas amounts an-nually to about $15,000,000. The loss in the weevil-in-fested counties of Texas is certainly fully one-half of thecrop. If we assume that the total cotton crop of theUnited States has a value of $500,000,000 it will be seenthat when the boll-weevil is found throughout the wholecotton belt the annual loss will be at least $250,000,000annually. All these estimates are based upon the fail-ure of t he planters to adopt any measures to check thespread of the pest or particularly to reduce the extentof its damage. We shall see that there is much hopethat cotton may be grown at a profit in the infested re-gions if the planters will adopt the modern methods ofplanting and cultivation suggested and urged by theBureau of Entomology of the Department of Agricul-ture.

LIFE HISTORY OF INSECT.

EGG.

The female weevil deposits the egg in a holemade by eating into either the square or boll. Thesecavities are made usually between the middle and thetip in the case of squares, but seem to occur at randomin the case of bolls. The length of the egg stage in thevast majority of cases varies from 2 to .5 days. It hasbeen observed that but a single egg is usually depositedin a boll if the female is able to find b6lls not punctur-ed. This habit of selecting a fresh boll for the ovi-position of each egg accounts for the large number ofbolls injured by a single female. It is probable that asingle female may deposit as high as 200 eggs duringthe season.

,114 . 1 1IL ) him414 1 .... n inch IuI :144 I 4 1 11141 xil444 I S' .

P ' . L ~ I 1 I f i! i t 44)4114 1'41 I I14'

14l('14 i.1411! IN4 Is 4111' 1 4';! I ' I 44 il\\ I. 44' I the

;Il!: '. 111444~ii Il:8 4154 tl4 1141141 11! t~ l:l tlu i

til . 1'l) i 141 m 1 1L11, 114 114 r1111( 11481 1 41 (V II 4./i 1:it.14.V

Iu I1 1444 I N 4'rntl44'1' 1114 ' 1111'4 8I111l~ 4 1 4(4484 ItrnlrILl'.

444:I 144I lIt 414 I 44441 ill 1144'sI IliX I1 I l 41, 4 1441115. I 144411 G tlI44V1441 t in 44)141 14114 ' It e 11(] L I I II l rtt is 1f cII se t)

v el rtt ltnu h ill 144 I4 I114 Lllv. in t I Lnl 14 !d ~ii1444141 :111441 t1144' (4'1114'14(4 44 1 171 14 81.

96

In the bolls the larval stage last probably muchlonger and here 6 to 7 weeks is near the length of thelarval period.

As the boll reaches maturity the mature larva, now 1-4to 1-3 of an inch long, ceases feeding and be-comes surrounded by a sort of cell composed oflarval excrement mixed with the lint, etc. With-in this cell the pupation and formation of the adultoccurs. The cells are shorter and thicker than cottonseeds, with which they are at times confused.

PUPA.

When the insects enters this stage it has muchthe. form of the adult, but its color is purewhite or cream. (See Fig. 3.) The pupa stagelasts in squares on the average three to fourdays in warm weather, but may reach a maximum of 15days in cold weather. The pupal stage is certainly long-er in bolls than in squares, but no definite data are athand on this point.

Fig. 3. Larva, to the left, and pupa, to the right. x6. (Farmers'Bull. 189, U. S. Dept. Agr.)

The final molt of the pupa requires about a half hour.

ADULT.

About 2 or 3 days are required for the adult to assumethe color typical of the species and to acquire sufficientstrength to enable it to walk. The weevils may varymuch in size dependent largely upon the question of

97

available food supply . With the proboscis extendedthey vary from1 -8 to 1-3 of an inch in length and in theminiddle of the body are from 1-25 to 1-8 of an inch broad.(See Fig. 4.)

t v,

Fig. 4. Mexican cotton boll weevil (Anthonomus grandis). x3(Bull. 45, Div. Ent., U. S. Dept. Agr.)

The color of the boll weevil varies with the size-thesmaller weevils being darker brown and the larger wee-vils being light yellowish brown. The average color be-tween these two extremes is a gray brown or dark yel-low brown. The yellowish color of the larger specimensis due to the presence of numerous yellowish scales thatare more conspicuously formed in large than small wee-vils. These scales, however, often become rubbed off,leaving the dark brown color of the chitin. The sexes,however, cannot be distinguished as is often supposedby any question of either size or color.

The average length of life of the adult weevils onsquares is about 10 weeks for males and 9 weeks for fe-males. On the bolls it is nearly 3 weeks for males, butonly about 2 weeks for females.

FEEDING HABITS.

Until the females begin to oviposit the feeding habitsof both sexes are alike. Bolls and leaves are seldom fed

98

upon so long as squares are available. The puncturefrom the outside is only large enough to admit the pro-boscis, to the tip of which the mouth parts are attached.The principal part of the square eaten consists of theanthers and pollen sacs. When these are reached thecavity is broadened out to give to the whole cavity muchthe shape of a flask.

The males are known to make on an average about 3feeding punctures per day, though during the first fewdays of adult feeding existence they may make as highas 6 to 9 punctures per day. They average, however,about 3 punctures to a square, and hence really do verylittle damage. The males, unlike the females, more fre-quently chose to puncture the square very near the top.

After the females begin to oviposit they eat less on onesquare or from a single puncture than before. Since aswe have said that as a rule a female oviposits but onceon a square and since most of her eating is done in con-nection with oviposition, it becomes clear that theamount of damage done by the females is much greaterthan that due to the males.

It has been demonstrated by experiment that theAnmerican upland cottons are much less subject to attackby the weevils than any others, and that the Egyptian(Mit Afififi) cotton is more subject to attacks than anyother variety. It is now known also that the boll weevilhas no food plant, native or cultivated, other than thevarious species and varieties of cotton.

NUMBER OF GENERATIONS.

No hard and fast line can be drawn betwveen the dif-ferent broods of the weevil-not even between thehibernated weevils and those of the first spring genera-tion.

It is probable that in the southern part of Texas fivebroods occur between 1 May and 1 December-this ison the assumption that the average life cycle of a genera-tion from egg to egg is about 42 days. In northernTexas and probably also in this region not more than4 broods would occur.

99

HIBERNATION.

Even after the cotton has been entirely killed by frostadult weevils may be seen moving about in the fields.In southern Texas the weevil may hibernate as eitherlarva, pupa or adult, but they most commonly hibernatein the adult condition. The majority of weevils thatsuccessfully hibernate over winter are those developedlatest in the fall-whose vitality was consequently notexhausted by oviposition or otherwise before the ap-proach of winter.

The average hibernation period is from 1 December to1 April, or about 4 months. Given a dry sheltered placeand as high as 1-6 of the weevils will live through thewinter.

DISSEMINATION.

The search for food or new squares is the principalagency leading to the migration of the weevils from oneplace to another. Prevailing winds may assist if theseoccur when the weevils are naturally most active, as doesoccur in Texas.

Artificial dissemination will take place most common-ly along railways and water courses. The shipment ofcotton baled or for ginning is nearly certain to meanshipment of the boll weevil. And the same is true ofshipments of seed for planting and other purposes. OurState law already quoted (page 93) should receive thesupport of every person living in the State and havingthe slightest concern for the welfare of the State. Inregard to pests of this and all other types legislative en-actment may develop public sentiment, but certainly cannever replace it.

METHODS OF CONTROL.

The methods of control may roughly be divided intotwo classes (a) natural, and (b) artificial.

100

Among the first group we mention in the first place cli-matic control. The factors of highest importance in de-termining the development, distribution and destructive-ness of the boll weevil are temperature, preci-pitation and food supply. We have stated that the wee-vil has but a single food plant-the cotton-and it isremarkable how thoroughly adjusted to the conditionof the food plant the weevil has become. Conditionsfavoring the growth of the cotton plant are also favor-able to the development of the weevil.

High temperatures and abundant rainfall are the twoclimatic factors distinctly favorable to weevil develop-ment, and hence it is that at such times their injury ismost noticeable. Rains tend to increase formation ofsquares by the cotton plant and the squares, we haveseen, are the feeding places and oviposition structuresfor the weevils. Rains also indirectly favor weevil de-velopment by the injury they do to the natural enemiesof the weevil.

Too heavy rains'during the winter are very apt to killmany of the hibernating weevils and hence following acomparatively dry winter one would expect to see alarger brood of hibernated adult weevils appear i- thespring than following a rainy winter.

Experiments have shown that overflows will not in-jure enough weevils to be of any great service. Even thelarvae and pupae in equares that have been under waterfor some time were found to be uninjured. Adult weevils may float several days in the water and yet not beinjured. It is very probable that the floating of adultand infested squares by means of high water will proveone of the most important natural agencies for widelydistributing the pest.

PARASITES, PREDATORY INSECTS, AND DISEASES.

The very recent announcement by an officer of theUnited States Department of Agriculture of the dia v-ery in Guatemala of an ant that preys upon the bollweevil has called forth renewed interest in this subjectof parasites or rather predatory insects. However,

101

it seems certain that the ant discovery has al-ready been overworked and its importance much ex-aggerated. Hunter & Hinds, 1904, say: "There is atpresent, therefore, no promise of any considerable as-sistance in the control of the weevil by any parasite nowknown. * * * Even should one be found which couldattack the weevil in some stage, it would probably stillfail to be an efficient means of control. * * * "

Certain predatory insects other than the Guatemalanant may serve to check the weevil, but the work of allsuch insects combined is comparatively of little import-ance when compared with the cultural methods mention-ed below.

And there seems to be but little hope of securing afungus parasite that will be of any service in killingweevils. A study of the history and outcome of the useof the "chinch bug" fungus and later the grasshopperfungus shows how utterly impracticable any such meth-od is certain to be.

In connection with the appearance of such an import-ant pest as the boll weevil there is certain to be a host ofuseless remedial and preventive measures suggested. Itwould be a waste of space to even mention all theseschemes here. Considerable attention has been devotedto devising some method of spraying the cotton plants inhopes of killing the weevils. We may for the present dis-miss any spraying scheme with a quotation from Hunter& Hinds, 1904, who say: "Spraying of a field crop hasnever been a success, and, unless entirely new methodsare eventually perfected, never will be of any practicalimportance."

Of course the suggestion made from time to time thatsome substance may be mixed with the fertilizer whichwill be distasteful to the weevil when absorbed by theplant is absurd.

It has proven impossible to devise a machine that willenable one to collect from the ground the fallen squares.

And it is even more absurd to hope to find any sort ofcotton that the boll weevil will not care to eat. There isa limit to the profitable variation in the cotton plant tobe induced by breeding and selection and there is cer-

102

tainly no hope of securing a strain of upland cotton thatwill prove resistant to the boll weevil, or to any other in-sect.

CULTURAL METHODS.

It has been demonstrated that improved methods ofcultivation will enable one and does enable many Texasplanters now to grow cotton at a fair profit in weevilinfested areas. If the weevil can force cotton plantersthroughout the cotton belt to adopt more civilized andmodern methods of cultivation we may be forced to lookupon the weevil as a "blessing in disguise."

It is impossible better to present the desirability andcertainty of iesults from the cultivation methods recom-mended by the Division of Entomology, UnitedStates Department of Agriculture, than to quote therecommendations given by W. D. Hunter, the officialagent in charge of the cotton boll weevil investigation.

"1. Plant early. If possible plant seed of the va-rieties known to mature early, or at least obtain seedfrom as far north as possible. It is much better to runthe risk of replanting, which is not an expensive ope-ration, than to have the crop delayed. The practice ofsome planters of making two plantings to avoid havingall the work of chopping thrown into a short period isa very bad policy from the weevil standpoint.

Under identical conditions early cotton if improvedvarieties has invariably yielded from two to three timesas much as native cotton under the same conditions,and in many cases much more. Planted at the same timethe early varieties begin to bloom from twelve to eight-een days sooner than native cotton.

Early planted fields of either native or improved va-rieties have almost invariably yielded twice as much aslate planted ones.

The early varieties in general, having a small stalkand a short tap root, are adapted only for rich soil. Theyalso fail to grow well in the very light sandy loams ofmany of the river valleys of Texas which, in long sea-sons before the advent of the boll-weevil, often producedthe largest yields. In these situations early varieties

103

will yield but little more than native cotton.2. Cultivate the fields thoroughly. The principal

benefit in this comes from the influence that such apractice has upon the constant growth and consequentearly maturity of the crop. Very few weevils are killedby cultivation. Much of the benefit of early plantingis lost unless it is followed by thorough cultivation. Incase of unavoidably delayed planting, the best coursefor the planter to pursue is to cultivate the fields in themost thorough manner possible. Three choppings andfive plowings constitute as thorough a system of culti-vation as is necessary in cases where the land has pre-viously been kept reasonably clear.

3. Plant the rows as far apart as experience withthe land indicates is feasible, and thin out the plants inthe rows thoroughly. On land which in normal seasonswill produce from 35 to 40 bushels of corn the rowsshould be 5 feet apart. Even on poor soil it is doubtfulif the distance should ever be less than 4 feet.

4. 1 estroy, by plowing up, windrowing, and burn-ing, all the cotton stalks in the fields as soon as the wee-vils become so numerous that practically all the fruitis being punctured. This will generally not be laterthan the first week in October. Merely cutting off thestalks by means of the triangular implement used forthat purpose throughout the south is by no means as ef-fective as plowing, because the stumps remaining giverise to sprouts which furnish food until late in the sea-son to many weevils that would otherwise starve. Theplowing, moreover, serves to place the ground in bettercondition for early planting the following spring. Insome cases turning cattle into the fields is advisable.Aside from amounting to a practical destruction of theplants, grazing of the cotton fields furnishes consider-able forage at a time when it is generally much in de-mand. Nevertheless, cattle should never be turned intocotton fields in which Johnson grass has become started.

5. It is known that at present fertilizers are notused to any considerable extent in cotton producing inTexas. There is, nevertheless, no doubt that theyshould be; not that the land is poor, but that earlier

104

crops may be procured. At present it is sufficient to callattention to the fact that it has been the uniform ex-perience of experiment stations and planters in theeastern part of the belt that certain fertilizers, especial-ly those involving a large percentage of phosphoric acid,have a strong tendency towards hastening the maturityof the plants."

BIBLIOGRAPHY.Mally, F. W.

1901. The Mexican Cotton-boll Weevil. Farmers'Bulletin, U. S. Dept. Agr. 130: 30 pp. fig. 1-4.

Hunter, W. D.1903. Methods of Controlling the Boll Weevil (ad-

vice based on the work of 1902). Farmers' Bulle-tin, Ti. S. Dept. Agr. 163: 16 pp. fig. 1-2.

Sanderson, E. D.1903. The Mexican Boll-Weevil. Texas Exp. Stat.,Ent. D)ept. Circ. 1: 8 pp. 4 figures.

Sanderson,. E. D.1903. How to Combat the Mexicon Cotton-boll Wee-

vil in Summer and Fall. Texas Exp. Stat. Ent.Dept. Circ. 4: 4pp.

Morgan, H. A.1903. The Mexican Cotton-boll Weevil. La. Exp.

Station, Circ. 1: 10 pp. fig. 1-3. 1 map.Cook, 0. F.

1904. Report on the habits of the kelep, or Guatemal-an cotton' boll weevil ant. Bull. Bureau Entom., U.S. Dept. Agr. 49:15 pp.

ilerrick, G1. W.1904. The Mexican Cotton boll weevil. Miss. Exp.-

Stat. Circ. 17: 7 pp. 2 figures.Hunter, W. D.

1904. In formation Concerning the Mexican CottonBoll Weevil. Farmers' Bulletin, U.. S. Dept. Agr.189: :31 pp. 8 -figs.

Hunter, W. D.1904. The Status of the Mexican Cotton Boll Weevil

in the United States in 1903. Yearbook, I.S.Dept. Agr. 1903: 205-214. pl. 17-21.

Hunter, WV. D., and Hinds, W. E.1904. The Mexican Cotton Boll Weevil. Bull. Div..

Entom., U. S. Dept. Agr. 45: 116 pp. 16 pl. 6 figs.