MARYLAND.

ovigultural E speriment Station,

oe 7

of the M BULLETIN. No. 2s.

‘ adie:

INJURIOUS INSECTS

OF

MARYLAND.

U / ent Otation/ .

/

COLLEGE “PARK; MD:

December, 1898.

MARYLAND

gricultural seperiment Station,

ADVISORY COMMITTEE OF BOARD OF TRUSTEES.

GOVERNOR FRANK BROWN......... Reise. Annapolis.

THE Hon. MARION DE KALB SmITH.....Chestertown. THE Hon. SPENCER C. JONES..t........... Rockville.

THE Hon. MURRAY VANDIVER...........- Havre de Grace. Tun Hon, DAVID: SEIBERT:...295/.2..---=-- Clear Spring. OLAYTON J. PURNELL ...... Renee oe Ae Snow Hill.

OFFICERS OF THE STATION.

Rospert H. MILLER............ Director.

Harry J. PATTERSON, B.S..Chemzst.

JASS Oe HOBINSONets: -Sc-0 27-3 Horticulturist.

CAVs) RIGENG © iy De cers. 7 o's: Entomologist and Physiologist. MILTON WHITNEY...-..-....... Physicist.

ERNEST H. BRINKLEY......... Assistant Agriculturist. Jos. Re OWENS, MD; -....2.- Treasurer.

P. B. Hassprouck, B. 6.......Stenographer. hLoeated on the B. &O.R.R., 8 miles N. of Washington, D.C.

DA ee |

ad The bulletins of the Station will be mailed free to any citizen of Mary- lan 1 who sends his name and address to the Station for that purpose.

Correspondents will please notify the Director of changes in their post- office address, or of any failure to receive the bulletins.

ADDRESS, MARYLAND AGRICULTURAL EXPERIMENT STATION,

COLLEGE PARK, MARYLAND.

ce,

LETTER OF SUBMITTAL.

MARYLAND AGRICULTURAL EXPERIMENT STATION, DEPARTMENT OF ZOOLOGY AND ECONOMIC ENTOMOLOGY,

COLLEGE PARK, MD.

DECEMBER IsT, 1893. SIR:

In accordance with your wishes, I take pleasure in submitting herewith a bulletin on some of the injurious insects of Maryland, with a treatment of the best methods of counteracting their injuries. It is my intention to follow this up from time to time with other bulletins of like nature, the particular subjects to be dealt with depending somewhat upon the inquiries received in the current correspondence of the Station, and upon the insect peculiarities of any particular year.

Respectfully yours, C. V. RILEY. Robert H. Miller, Esq.,

Director, Maryland Agricultural Experiment Station.

THE MARYLAND

AGRICULTURAL EXPERIMENT STATION.

Bulletin No. 23. December, 1893.

*

SOME INJURIOUS INSECTS OF MARYLAND.

Bs Cove RGH Yer. 2D:

INTRODUCTION.

This is the first of a series of bulletins which I hope to issue from time to time upon the insects of Maryland. In my governmental work it is my object to avoid threshing over old straw and republishing anything that has been published before, as I conceive itto be the chief function of the Department of Agriculture and its various Divisions, to prosecute original research and to investigate those problems which yet remain to be solved. To a certain extent this I hope to do, as an officer of the Station, for the entomology of Maryland; but for the present I feel that it will be more productive of good to devote these bulletins primarily to those insects which are most important to the farmers and fruit growers of the State, by giving summaries of all the more important facts in refer- ence to them, and dwelling more particularly on the methods of counter- acting their injuries. The average farmer has little use for detailed descriptions of the forms of the minute life with which he has to deal, and for their recognition it will be better to depend upon good illustra- tions, with the barest indication of the colors and other salient character- istics. The figures in this bulletin, unless otherwise stated, are from my

own drawings, or else from those made under my supervision.

THE CODLING MOTH.

(Carpocapsa pomonella L.)

LIFE HISTORY.

Wormy apples are fully as abundant in Maryland as in other states of the Union, and this worminess is due almost entirely to the larve of the Codling Meth. A little mass of brown excremental grains about the

valyx end of the apple, or more rarely issuing from a small hole in its

side, indicates the presence of this insect. Upon cutting the apple open these holes are seen to lead to rapidly broadening tunnels reaching to the core, which is often eaten through or surrounded by the nauseous brown cavities.

The perfect insect is, as shown at Fig. 1, a small grayish moth, > which issues from its cocoon about the time the trees are in full bloom,

and soon thereafter lays its eggs in

the forming fruit, choosing the calyx cavity or its immediate vicin- ity for this purpose. The eggs hatch and the young larve gnaw their way through the skin and into the fruit, moving up and down free- ly in their burrows and enlarging the entrance holes to push out their excrement. Inabout a month they become full-grown. By this time the infested apples have begun to fall to the ground; but whether they fall or not, the larve bore to

Fig. 1.—Carpocapsa pomonella; a, apple the sides and issue through a round showing the work of the larva; b, point of hole. If issuing from a fallen apple, moth: h head of larva icacoon. *® they crawl back to the tree trunk and mount it until some convenient crevice or piece of loose bark is found, and here they spin their cocoons and transform to the pupa state. If issuing from an apple which has not fallen, however, they crawl down the branches until they reach the rough bark of the trunk, on which, as in the other case, they spin their cocoons.

A few days after completing the cocoon, the larva in this first or summer generation changes to the chrysalis state, and in about two weeks, on the average, from the time of leaving the apple, issues as a moth. The female soon begins to oviposit, at this season not so uniformly in the calyx end as was the case with the preceding generation in the spring. This summer generation of moths issues quite irregularly, covering a

im)

72 MARYLAND AGRICULTURAL EXPERIMENT STATION.

period of several weeks, and egg-laying thus extends into the late summer, so that larve of different sizes will be found in the apples during the late summer and autumn, and even well into the winter. The cocoons of these late individuals are usually spun in the crevices of the barrels in which the apples are packed for storage.

REMEDIAL MEASURES,

The damage which this insect wrought to the apple crop all over the country down to within the last eight or ten years was very great, and is still very serious in sections where intelligent measures are not taken to prevent it. Anywhere from 50 to 100 per cent. of wormy apples was common ; and the effect of the alternate seasons of heavy and light setting of fruit was intensified to such a degree that in seasons of light setting, the crop was almost entirely destroyed.

In a few localities the old plan of bandaging or encircling the trunks of the trees with paper or rag bandages was systematically carried on, with the result of greatly reducing the proportion of wormy fruit, as the larve are very fond of spinning up in the shelter afforded by such ban- dages, and where these are systematically removed every two weeks and scalded, (or in the case of paper bandages burned) this method of check- ing the injury of the insect is well worth adopting. The efforts of the State Horticultural Societies of Michigan, Illinois and Kansas in the use of these bandages were particularly productive of good results, as there was co-operation. At the present time, however, this method has been almost entirely superseded by one which is, on the whole, better and simpler, viz: spraying with arsenical poisons. The use of arsenical poisons against this insect practically dates from 1878, though they had been employed on apple treesas early as 1872, against Canker Worms. It was in fact, their use against Canker Worms that led to the discovery that they were available as preventives of the Apple Worm. They are now very generally employed among the most advanced apple growers of the North and West, especially where a sufficient number of trees is grown to justify providing the proper machinery. This method is not confined to the United States, but has been introduced with profit into New Zealand, Australia and Tasmania, where the insect prevails as it does with us. Spraying with arsenicals was longer in making its way in Europe, but even in England and in parts of the continent apple growers are beginning to appreciate its value, though prejudiced against the use of poisons. Many of our apple growers, particularly in the South, have so far failed to appreciate its importance, and this is to a large extent true of the State of Maryland.

As some of our orchardists may yet fancy that the time and means required to spray effectively are wasted, let me quote a single instance of the value of spraying from a correspondent in the vicinity who is an ex- tensive grower, and then giye briefly some of the best and latest methods. nae years ago Mr. John 8. Lupton of Winchester, Va., wrote me as ollows:

BULLETIN NUMBER 23, DECEMBER, 1893. 73

“Please allow me to acknowledge my very great obligation to youfor bringing to my attention, through your official publications, the use of arsenical poisons for destroying Codling Moth and other noxious insects.

“T have a fine young apple orchard of fifty acres, all Newtown Pippins, immediately

adjoining which on the north is an older and much neglected orchard belonging toa neighbor.

“The old orchard has been badly infested with worms for many years, and until the present season the north half of my orchard has been practically worthless, the trees shedding most of their fruit in May and early part of June, the little which remained being so wormy as to be largely unfit for market, while the south half has borne fair crops, comparatively free from worms.

“Soil, drainage and other conditions being similar throughout, lam constrained to the belief that the near proximity of the old and worm-infested trees to the north side of my orchard is the cause of the difference above noted.

“Acting upon information obtained from one of your pamphlets, I bought last spring a full spraying outfit, using the Climax preparation of London purple sold by the Nixon Company.

“Soon after the blossoms fell I began spraying on the side nearest the old orchard,the machine working perfectly, the Climax nozzle breaking up the solution into a fine mist which completely enveloped the trees.

“After working a day anda half and applying the poison to about one-third of the trees, I suspended operations on account of the weather becoming so windy as to make the work exceedingly disagreeable, one of the men having been made sick by having the poison blown into his face.

“Influenced to some extent by the skepticism of my neighbors, most of whom regard- ed the experiment as highly dangerous, and confessing to no small lack of faith myself, IT regret to say that I allowed other work on the farm to interfere, and never finished the work of spraying.

“With the mental reservation that should the heretofore barren north side where the poison had been applied do as wellas the south half, I would spray more thoroughly next year, I waited the outcome with an indifference born of unbelief. Please note the result. From the sprayed trees, not quite one-third the whole number, I gathered 1,000 barrels of Al merchantable fruit so entirely free from worms that sorting was almost unnecessary, while the remaining two-thirds of the orchard yielded 883 barrels of good fruit, quite one-fifth of the apples on the unsprayed trees being wormy and unfit for sale. The market price of apples in this section the past season was from 60 to 75 cents per barrel, one or two choice lots of Ben Davis and York Imperial bringing $1 per barrel, while my fruit sold in the orchard nearly a month before picking at $2.55 per barrel.

“T estimate the cost of failure to spray the whole orchard at $2,500, but consider the lesson cheap at the price, as I shall never have it to learn again, and feel confident that with ordinary care no harmful results will follow spraying.”

THE USE OF ARSENICAL SPRAYS.

Substances to be used.—Two arsenical poisons are commonly used in spraying orchard trees for the Codling Moth, namely, Paris green and London purple. Of the two, Paris green still holds the vantage ground by virtue of the fact that it is insoluble in cold water and contains a more constant proportion of arsenic. London purple, on the other hand, is somewhat cheaper, and the slightly purplish hue which it imparts to the treated foliage possesses some value as indicating more clearly the efficacy of the spraying, for it permits us to see whether or not the appli- cation has been uniformly made and has taken a firm and uniform place upon the leaves, which the Paris green does not show to the same extent. The slight solubility of the purple in cold water renders it more apt to

©

74. MARYLAND AGRICULTURAL EXPERIMENT STATION.

burn the foliage, but this difficulty is easily overcome by the addition of a small quantity of lime water to the mixture, thus transforming the sol- uble arsenic into insoluble calcic arsenite,

The use of ordinary white arsenic is not advised because of its in- solubility and its color, which renders it indistinguishable from some harmless substances for which it is apt to be mistaken, so that it is more dangerous to have about the farm in quantities.

Kither London purple or Paris green, then, should be thoroughly mixed with water in the proportion of one pound of the poison to 150 gallons of water, and this mixture should be thrown in a fine spray through the trees, so as to thoroughly moisten all parts of the leaves and fruit. I cannot too strongly urge the advantage of careful spraying which shall cause a uniform fall in the form of a mist, and not drench the tree, and thus cause the concentration of the poison in particular spots. The spray should be forced from the center of the tree and then all around it, in an even mist, which will settle uniformly on all parts.

The first application should be made about a week after the blossoms.

fall and before any of the larvee have hatched or entered the fruit, as the efficacy of the spraying depends upon the larve taking a small quantity of the poison with their first meal in eating through the calyx of the young apple. Unless a heavy fall of rain should follow this first appli- cation, the spraying will not have to be repeated. A small quantity of flour or starch mixed in at the time of stirring the poison in the water will tend to make the spray adhere better and more uniformly, but these sticky substances should not be mixed with London purple as they pre- cipitate the poisoh and rather increase the inequality of its distribution.

One great advantage of such spraying is that in addition to greatly lessening, if not practically checking, the work of the Codling Moth, it also destroys a great number of insects which feed upon the leaves of the apple tree, and in a measure will also serve as a protection against certain fungus diseases. Where orchards are seriously affected with rust or scab, it is desirable even to combine with the arsenical spray a certain amount of Bordeaux mixture, and a good formula for this last is, 7 poumes of unslaked lime, 6 pounds of copper sulphate (or blue stone), 3 pound of London purple, and 75 gallons of water.

Apparatus for Spraying. —For orchard use, the knapsack pumps or bucket pumps are practically unavailable, however useful for a few trees by means of ladders. I shall therefore not consider them in this connec- tion, but refer to a few of the more important tank or barrel pumps and state the requisites of a good orchard spraying apparatus.

The following firms manufacture Spray pumps of several styles*and are always glad to send circulars to fruit growers:

Nixon Nozzle & Machine Co., Day ton, Ohio.

Field Force Pump Co., Loc ‘kport, N. Y.

Deming Manufacturing Co., Salem, Ohio.

W. & B. Douglass, Middletown, Conn.

The Gould’s s Company, Seneca Falls, N. Y.

BULLETIN NUMBER 23, DECEMBER, 1893. 75

A good, strong double-acting force pump should be purchased and mounted on a large stout barrel with the supply tube reaching well down to the bottom. It has become the custom to mount the pump in the end of the barrel, but except in the case of the Nixon Tripod, it will be al- most as easy to mount it on the side of the barrel, which is easily held in place by a skid near either end, and is then more compact and stable than when standing on the end, while the handle of the pump comes lower and is more easily worked.

It will be well to buy the pump without attachments. About 25 feet of + inch cloth insertion rubber tubing is attached to the discharge orifice, or to each of the orifices in case there are two. To the end of the tube is fitted one of the modifications of the Cyclone or Riley nozzle and the outer 8 or 10 feet are clamped or wired to a light pole or bamboo fishing rod for convenience in elevating the nozzle into the larger trees, The tank or barrel is mounted on a cart or sled and driven between the tree rows, one man driving and pumping and the other holding and directing the extension pole and nozzle.

T have mentioned the cyclone nozzle for the reason that, all things

ah vinaszett HH } ‘ i} Wt Mil

ured and sold by the Nixon Nozzle & Machine Co. is also a good nozzle, but it is rather “large and clumsy, its spray hardly so fine, and it will not answer for fungicides contain- ing lime, since it clogs easily. The Vermorel modifi¢ation of the Cyclone nozzle (Fig. 2) pos-

B ‘ eae ome Are, Modification of uhe Cy- sesses a little attachment which clone Nozzle—natural size (Original).

A, entire; B, in section; c, removable cap; d, end quickly unclo Se sule orifice of cleaning rod; e, rubber casket to prevent back- when once stopped up, and is ward escape of liquid; f, cap to hold liquid when ,; ft ; cian : ; cleaning rod is pushed forward. therefore preferable. More- over, neither the Cyclone nor the Vermorel modification is patented, which, other things being equal, is in their favor. Both are manufact- ured by Thomas Somerville & Sons, Washington, D. C., and Robert Leitch & Sons, also of Washington, or may be made by any brass and iron worker from the descriptions in my official reports* or from the accom- panying figures.

NATURAL ENEMIES,

While ordinarily little can be done to encourage the natural enemies of the Codling Moth, there are nevertheless a few which it is well worth while for the orchardist to become familiar with. Those of its own class which he will most often meet with in sheltered situations, about the trees or under the bandages used to trap the worms are the followin g:

“INSECT LIFE, Vol. I. p 243-244: Fifth Report U. 8. Entomological Commission, p 45.

76 MARYLAND AGRICULTURAL EXPERIMENT STATION.

THE PENNSYLVANIA SOLDIER BEETLE.—(Chaultognathus pennsyl- vanicus De Geer.) This is a little yellowish beetle (Fig. 3, 2) with ‘. £ inore or less black upon its ~‘y’,; Wing-covers and upon the thorax, ~ mm abundanton almost all pollen-bear-

7- ing flowers; but while the beetle is Pe ~ pollinivorous, the larva is carnivor-

6 ous and devours the apple worm

. / ¢ ™ either within the apple or while it Fig 3—Chauliognathus pennsylranicus: a,is getting ready to spin up. The larva, natural size: P, Read and Sst seement -companying figure (3) shows this

leg: 7, left maxilla: g. antenna: h, left man-jynzp ; = a ng insect in the larva state at @ and

the adult at ¢, the other figures indicating details of the larval structure.

i «

es yO

ae

hae

rg)

COREL ET)

‘

THE TWO-LINED SOLDIER BEETLE.--This is an allied species belonging —

x to another genus and known entomologi- — cally as TZelephorus bilineatus Say. Here alsoitis the larva which preys upon the apple worm. Figure 4, shows it in natural = size at a, its head and two thoracic segments -® at 4, enlarged, and the beetle natural size

Fig. 4.—Telephorus bilineatus. a.at c. The larva, like the preceding, is of a - anlareed image OF S8™€ rich, velvety-brown and black color, the beetle having brown and black wing covers and reddish-yellow thorax, the latter having two short black longitudinal marks, from which the insect takes its name.

In the Fourth Report on the Insects of Missouri, 1871, I called at- tention to the fact that the principal bird enemies of the Codling Moth are the Creepers, Black-capped Titmouse, the Downy Woodpecker, the Blue Bird and the Crow Black Bird. In the Fifth Report of the same series I described and figured two true parasites. The Ring- legged Pimpla (Pimpla annu- Ziges, Br.) and the Delicate Long Sting, ( Macrocentrus deli- catus Cress.,) and there men- — tioned the fact that a species of Hair-snake or Hair-worm, - (Mermis acuminata), also in- fests the larva. All of these an =. insects are found in Matyland. - Fig. 5.—Tenebrioides corticalis: a. larva; ¢, its man- I have also found a peculiar =

dible: d. antenna: ¢é. under side of head: 7, the two-

horned anal plate: b. the beetle: h, its antenna: i. larva of another Beetle, ( Zene- mandible; g. labium and its palpi: j. one of the - - - ee = maxilla and its palpus. i orioides corticahs, Fig D)s prey-s ing upon the larve, while Dr. LeBaron, (Fourth Report as Illinois State __ Entomologist, p. 64), records the same habit of the same species and Mr. _ C. D. Zimmermann records a similar habit, on the part of the larva of LT. laticollis, (Canadian Entomologist, 1878, p- 60). In Europe three

BULLETIN NUMBER 23, DECEMBER, 1893. TT

Ichneumon flies prey upon the Codling Moth. These are Phygadeuon brevis, Pachymerus vulnerator and Campoplex pomorum Rtz. On the Pacific Coast the Ring-legged Pimpla, (Pimpla annulipes Br.,) is an im- portant parasite of the Codling Moth, as ascertained by Mr. Albert Koe- bele who has also found several new enemies of this insect there. Two

Dermestic beetles also feed upon the pupa in California. These are Trogoderma tarsale and Perimegatoma variegatum as shown in my Annual Report as U. 8. Entomologist, for 1887. Mr. Koebele has also found a species of the Chalcidid genus Trichogramma, which infests the eggs of the Codling Moth and has further observed that the larva of a species of the very peculiar Neuropterous genus Rhaphidia runs up and down the ree trunks, searching for Codling Moth larve and pup (see Bulletin 22, Division of Entomology, Wigs: Department of Agriculture, pp. 90-92).

Mr. Koebele has also reared a parasite of the genus Pteromalus, but this may be a secondary parasite on the Pimpla above mentioned or upon one of two other primary parasites of the genera Cryptus and Phygadeuon which he has also reared from Codling Moth cocoons.

Some of these California insects were sent by me through Mr. Koebele to New Zealand and Australia, for the purpose of introducing them into the apple orchards of those countries, and they as well as the European parasites, are mentioned in this connection, as it may be desirable in special cases to introduce them into apple orchards in the eastern United States.

THE GREEN JUNE. BEETLE.

(Allorhina nitida L.)

This is an insect which has become more and more noticeable during recent years and has at times proved exceedingly destructive, especially to lawns in the vicinity of Washington. It is very common in Maryland, where it is known ordinarily as the June Beetle or the June Bug, a term which has, however, been very loosely applied to several insects and par- ticularly to the common May Beetle (Lachnosterna fusca). These May Beetles, or June Bugs as they are called in the northern states, of the genus Lachnosterna, are brown beetles which begin to fly in the month of May, though they continue into June and even later, in the latitude of W ashington. Under the circumstances it will be w ell to designate the insect Iam now treating by the name indicated in the title. The larve of this insect and those of the May Beetles, havea similar general appearance and are known popularly among farmers by the rather comprehensive name of White Grubs. The ‘leprae of the true May Beetles are, as a rule, smooth and naked in appearance, though when examined under a strong lens, minute stiff hairs or bristles may be found on different portions of the body. But the larva of our Green June Beetle is clothed with min- ute yellowish hairs in sufficient numbers to make them easily observable with the naked eye. The two kinds of White Grubs may be further dis- tinguished by the fact that when the larva of Allorhina is placed on a smooth surface it will immediately turn over on its back and rapidly move away by the alternate expansion and contraction of the body seg-

78 MARYLAND AGRICULTURAL EXPERIMENT STATION.

ments, while the White Grubs proper, the larve of Lachnosterna, will lie in a half-coil on their sides, or make awkward efforts to use their feet, being essentially burrowers. It is for these reasons that I have figured the larva of Allorhina on its back, as shown in the accompanying illustra~ tion, (Figure 6).

Fig. 6.—Allorhina nitida; a, larva; 5, pupa, ¢, imago: d,g, mouthparts of larva; d, man- dible;e, antenna; f, maxillary palpus; y, maxilla.

The larve of the Green June Beetle attract more attention than the others, partly because they are somewhat larger in size, and partly because they occur abundantly every year and are more easily brought by disturb- ances and by irrigation to the surface of the ground. The parent beet- les begin to fly the latter part of June, increase somewhat in numbers during July and August, and disappear in September. Like the other species of its sub-family this Green June Bug does not devour the leaves, like the true May Beetles, but feeds upon over-ripe fruit and vegetables. It is fond of clustering in numbers upon anything that is over-ripe or half decayed, especially half decayed melons, and does in this way more or less damage to ripe peaches hanging on the tree. It will swarm around the flowing sap of fruit trees or even of young oaks and maples, wherever there is a braise inducing such flow, and I have noticed that they are particularly fond of feeding at the moisture that frequently re- sults from the attacks of borers. <A closely allied species, Auryomda me/- ancholica is commonly known as the Fig-eater from its similar habit of attacking fully ripe or over-ripe figs. Nevertheless the damage which the parent beetle does is slight compared with the injury which the species often does in the larva state.

Although so common, the readers of this bulletin will be surprised to learn that there is a great deal yet to learn in reference to it, and that its full life-history has not been traced. This is largely due to the fact that the larva works under ground and out of sight, and to the further fact that it is somewhat difficult to rear in confinement. I received two spec- imens of this larva in November; 1868, from Mr. G. D. Baker, of South Pass, Ills., who found them in his strawberry beds in company with one of the May Beetle larve, and it was at once noticeable that this Green June Bug differed from all I had up to that time studied in its peculiar habit of crawling on its back, traveling with the same motion and quite as yvapidly as an ordinary caterpillar, and invariably turning on its back to move or to burrow. ‘I'hese larvee remained alive in-doors, feeding greed-

BULLETIN NUMBER 23, DECEMBER, 1893. 79

ily on roots of wheat which I grew for them. In April, 1869, they formed tough, hard cells of earth, and by the middle of May had changed to pupae (Fi igure 6, 4), the adult beetles i issuing in June.

Around Washington these larvee are observed almost every autumn, and are not infrequently brought to me by persons who find them crawl- ing in large numbers on the eround, This is particularly the case on the sidewalks” adjoining the lawns of the Capitol grounds, where they are sometimes so numerous that bushels of them may be swept together.

The beetles lay their eggs, unquestionably, underground, and though the egg has not yet been observed or described, there is no question in my own mind that the beetles are attracted to any soil which is heavily mulched and where there is manure or decomposing vegetation. I have seen them swarming and buzzing lazily over the ground on the New Jer- sey coast wherever the sand was covered with sea-weed or marsh grass, settling down ever y once ina while to enter the ground or get beneath the mulching. There is every reason to believe from the size of the larve and the habits of the beetles, that the eggs are laid during any of the summer months, and even during September. The early life- -history of the larva has not been studied, but it is well-known that as it attains full growth it injures the roots of vegetation. Yet my own impression is that during most of their growth these larve are comparatively harmless, feeding largely on vegetable humus and deriving the greater part of their nourishment in this way. The contents of ‘the very large alimen- tary canal in color and consistence, would indicate this habit.

The exact length of the insect’s life in the larva state is also not accu- rately known, and this is one of the points which is now being investi- gated at the Station. In late autumn two distinct sizes are noticeable, though larve of almost every size may be found. The prevalence of these two sizes would indicate that the larva requires perhaps two years for full development, yet I am more inclined to attribute the difference in size to differences in the period of egg-laying and hatching and to believe that the insect may go through all its transformations in a single year.

It will thus be seen that there are many points yet to be ascert tained in the life-history of this insect, common as it is, and that some of these, when ascertained, may give us a clue to a better management of it.

REMEDIES AND PREVENTIVES.

Undoubtedly one of the best available remedies which we have, and one which is by no means extravagant in cost in a strawberry bed where plenty of water is convenient, is the application of a dilute kerosene emul- sion. ‘The experiments which I had tried a few years ago on the lawn in front of the east wing of the Capitol at Washington, (see Insect Life, Vol. IL, No. 2, pages 48-50, Aug., 1888), showed that one part of the standard kerosene emulsion diluted with fifteen parts of water, and subsequently well washed down into the soil by copious applications of water, will kill all the grubs which it touches, and at the same time will penetrate suffi- ciently “deep into the ground to reach those grubs which are furthest down, Moreover it is found that even at a strength of one part of the emulsion to eight parts of water, the grass is not injured. In addition to

80 MARYLAND AGRICULTURAL EXPERIMENT STATION.

this it was found that heavy watering will cause these grubs torise to the surface of the ground. We have, then, simply to pour an abundance of water upon the affected soil and when the grubs begin to appear upon the surface of the ground, to treat them thoroughly with the emulsion at one part to fifteen of water. Then, after say “bw enty-four hours, pour on more water to carry the insecticide further down into the soil. The economy of this plan may be shown by the following facts: One barrel of kerosene cos sting $4. 50, and a sufficient quantity of : soap to make half a barrel of strong soapsuds, co sting, say, twenty-five cents, will make a bar- rel and a-half of standard emulsion or twenty-two and-a-half barrels of the dilute emulsion. This will be amply sufficient to treat an acre of strawberries and even more upon a porous soil. Upon large field crops this process would prove too expensive, but as a matter of fact, this insect is always most abundant upon small, choice, heavily manured or mulched crops, and there is seldom any occasion for treating field crops.

A most interesting case was reported ‘to me the present season by Col. Wright Rives, of Rives Station, Md., near the College. An acre of choice celery y upon his place was found to be fairly teeming with these grubs. They did not seem to injure the celery by attacking the roots, but dam- aged it by carrying dirt into the heart’ and inducing rot by contact with ‘ici acid excrement. U pon investigation I felt quite certain that the heavy mulching and large masses of rotting straw which had been accu- mulated in the neighborhood, had served to attract the parent beetles, and thus induce their concentration upon the celery beds. The experi- ments which Mr. Lull has recently made upon Col. Rives’ place prove that the application of the standard kerosene emulsion, as above recom- mended, or at the rate of one part to fifteen of water, does not injure the celery in the slightest, while it kills the larva when they are at or near the surface of the ground. Experience this autumn with these larve shows that in addition to the food-habits already indicated, they are, on occasions, quite inclined to be carnivorous, so that when several are placed together in a breeding-cage or jar they invariably feed to some ex- tent upon each other.

As this larva has not yet been fully described, I close this article with a technical description, which will have some ‘entomological value, though descriptions of these Lamellicorn larve are necessarily unsatis- factory except by comparison with other allied forms.

Allorhina nitida.—Full grown larva.—Length, 40 millimetres, somewhat largest posteriorly, “sub- cylindrical, broader at thorax and eighth and ninth abdominal segments, which are materially swollen. More flattened ventrally, with a ‘distinct swollen lateral ridge just below the stigmata, which rather increases the flattened aspect of the venter. General color, glassy yellowish white, inclining to green or blue towards the extremity. Head, rather small, flattened, well inserted into the prothoracic segment, chestnut brown in color. Dorsal surface of the body strongly transy ersely corrugate or wrinkled, each of the chief seg- ments having three distinct ridges, the whole body studded with short, thick yellowish bristles, which are most dense on the dorsal ridges and

BULLETIN NUMBER 23, DECEMBER, 1893. 81

more sparse, but longer,on the ventral and anal segments. Dorsally these stiff hairs are directed posteriorly and materially assist in the dorsal locomotion. ‘The legs are honey yellow, covered with similar stiff bristles without definite tarsal claw. ‘They are short, compared with the larve of Lachnosterna, generally. Prothoracic segment with a honey yellow horny plate in front of the spiracle, which, as usual, is rather larger than the abdominal spiracles. Mandibles short, stout, dark brown, with the left (looking from the dorsum), 4-dentate and the right, 3—dentate. Antenne short, 4-jointed, joints sub-equal in length, diminishing in width, from 1 to 4, maxillary palpi, 3—jointed, joints sub-equal in length, terminal narrowest at tip. Labial palpi, 2—jointed, joint 1 longest, somewhat swollen at tip and bearing a short poiuted joint 2, on the inner side of its tip. Labium covered with short stout bristles. Maxille with long, stiff bristles on the inner surface and with two long, sharp, black teeth near the tip. The half-grown larva does not differ in structure or coloration. CABBAGE WORMS. Six different species of caterpillars or worms, affect the Cabbage very commonly, in the state of Maryland. All feed upon the outer leaves, fr) often boring well into the head. They are known by the following names: The Imported Cabbage-worm (larva of Pieris rape L.), the Cabbage Plusia, ( Péusza brassice Riley), the Cabbage Mamestra, (JZamestra trifolii Rott.), the Zebra Caterpillar, (larva of MJamestra picta Harvr.), the Cabbage Evergestis, (Zvergestes rimosalts Gn.), and the Cabbage Plutella or Diamond-back Moth, (Plutella cructferarum \.). All of the insects will be found treated at some length in my annual report, as Entomologist to the U. S. Department of Agriculture, for 1883, to which I would refer those who care to go into the details of the subject. For the purpose of ae Peer suis bulletin, it is my desire to dwell principally on

pw: d,larva:b,chry- the facts of practical value. salis,

THe ImporTED CABBAGE WorM (Pieris rape), is a pale green vaterpillar, about 32mm. (one and a quarter inch) long when full-grown, (Fig. 7, a). It is very finely dotted with black, has a faint yellowish line down its back and a row of. yellow dots along each side. It

Fig. 8.—Picris rape, male Fig. 9.—Pieris rape, female:

52 MARYLAND AGRICULTURAL EXPERIMENT STATION.

hatches from a minute yellowish, ribbed egg and transforms to a pale green cbrysalis, covered with small black k dots, Giee ye d). The adult butterfly is the common white or yellowish white species, with black spots, as at Figures 8 and 9, seen flying about cabbage patches.

THE CABBAGE PLUSIA (Plu-

sta brassicé) is also a green caterpillar but is larger “than

the preceding and lighter in color. It is marked with lighter longitudinal — stripes and is very soft bodied and tender. It measures 2 inches in length when full-grown, (Fig. 10, a.)

The egg from which it hatches is pale greenish yel- low in color, convex in shape and two-hundredths of an inch in diameter. In trans- forming to pupa the caterpil-

Fig. 10 —Plusia brassicw; a, caterpillar; b, chry- lar spins a delicate semi-trans- Salis in cocoon; ¢, moth, male. parent web usually partly or entirely wrapping itself in a leaf, (Fig. 10, .) The adult insect is a dark gray moth with a wing spread of about 14 inches and marked with a bright silvery dot and V-shaped mark near the center of each front wing, (Fig. 10, c.)

THE CABBAGE MAMESTRA (Mam- estra trifolit) is a variable caterpil- lar in color, some being bright green above and some nearly brow n, but all are marked by a rather broad pink stripe down each side, (Fig. 11, 4 c.) It transforms to pupa in an oval cavity about two inches below the surface of the ground. The parent moth is some- what variable in size and color, ranging from a pale yellowish-gray to a dark brownish-gray but mottled as in the figure, (Fig. 11, 2. dP ae is readily “distinguished from the moth of the Plusia by lacking the silvery spot on the front wing. This insect is more common in Maryland iMag cabbage-fields than I have known it * Fig. 11.—Mamestra trifolii; a, b, larvee: ¢, elsewhere.

pupa; d, moth; e, wing Or same (enlarged): f, anal segment of pupa. \

.

ne oe a ee, ee Premera

BULLETIN NUMBER 23, DECEMBER, 1893. 83

THE ZEBRA CATERPILLAR (larva of Mamestra picta) is a very easily distinguished in- sect. When first hatched it is almost black but soon becomes pale and green. When full- grown it is 2 inches long, velvety black, with tawny red head, ‘legs and belly and two narrow yellow lines along the side between which are many white irregular zebra-like finer lines. The pupa is found, like that of the preceding species, S—~ beneath the surface of the \. ground. The front wings of the adult moth are rich pur- ple-brown and the hind wings

; are white, faintly edged w ith Fig. 12.—Mamestra picta; a, caterpillar; b, moth. brown, (Fig. 12).

THE ee EVERGESTIS OR CABBAGE PRONE as it used to be called (Z£vergestis rimosalis) is a small purplish-brown or bluish- brown worm w ait a greenish-yellow head and green venter. When full- grown it is a little over half an inch in length and transforms to pupa at the surface of the ground i in a slight oval cocoou covered with earth. The moth % is pale ochre-vellow in color, the front wings dark- ening towards the tip, with the hind wings semi- transparent near base, (Pigal3;. 2). has a wing Fig. 13.—Evergestis rim- Spread of about 1 conve This caterpillar is rather ei Py nee pupa: ¢ fond of boring into the cabbage heads w hich ren- (enlarged). ders it more destructive and harder to treat than if it confined itself to the outside leaves.

THE CABBAGE PLUTELLA (Pluitella cruciferarum) 18 a little, active pale green worm, something over a quarter of an inch in Jength. It pupates within a delicate gauze-like cocoon resembling lace. The parent moth has narrow wings —expanding five-eighths of an inch, and is of an ash- gray color, usually with an undnlate pale streak along

e Fig. 14.—Plutellacruciferarum; a, larva (enlarged); the inner border of the front »,dorsum of a single /oint (greatly enlarged); a eee aie ae =. er side view of same; d, pupa (enlarged); e, aeons Wwilgs, (Fig. 14.: f. &); W hich (enlarged); f, moth (enlarged); g, Wing of derk va- o1ves a ser 1es of cdiamond- riety (enlarg ged); h,moth at rest (enlarged);i, cre- © ri Q master of pupa (greatly eularged). shaped marks when the wings

84 MARYLAND AGRICULTURAL EXPERIMENT STATION.

are closed. This worm feeds only on the outer leaves of the cabbage. REMEDIES FOR CABBAGE WORMS.

All of the above-mentioned cabbage worms are amenable to “about the same treatment. In my 1883 Report, already referred to, I recom- mend hot water (ata temper ature of about 130° F. apy ethrum powder, 200 grains to 2 gallons of water, and kerosene emulsion. I also mentioned the fact ‘that dr y applications of lime, salt, pepper, bran, buckwheat flour, road-dust, soot, or of any other fine pow “der are efficacious against the young worms and quoted Mr. P.'T, Quinn’s remedy of sawdust, im- pregnated with carbolic acid as wellas an anonymous remedy from the N.Y. Tribune of 20 parts superphosphate of lime, 3 parts shell or fresh air-slaked lime and 1 part of carbolic powder. I also mentioned the fact of the efficacy of the arsenical poisons, but stated that few persons would use them for fear of their poisonous effects.

Since that time little has been suggested that is new, but many ex- periments have been made with the remedies mentioned above. Prof. Lawrence Bruner of Nebraska claims that corn meal dusted on the cab- bages causes the worms to fall off and protects the crop until washed off by rain. It should be applied in the morning while the dew is on.