242

flDtolano Counties Section.

LIST OF OFFICERS. (1907.) Chairman: J. M, Lores.

Vice-Chairman: W. R. Witsoy.

Committee: T. Aksbll. W. H. Evass. Adbiak J. Bbown, M.Sc, F.I.C., H. L. Hind. F.C.8. R. L. Siau. W.W. Botxbb, F.C.S., F.R.M.S. F.L. Talbot. J. A. Evans.

Hon. Treasurer: W. L. Hodokinson.

Hon. Secretary: Abchibald S. Bbnnbtt, Liverpool Chambers, Cherry Street, Birmingham.

MEETING HELD AT THE GRAND HOTEL, BIRMINGHAM, ON THURSDAY, DECEMBER 13th, 1906.

Mr. J. M. Lones in the Chair.

The following paper was read and discussed :—

Some Injurious to Barley and other Grain when in Store.

By Walter E. Comjnge, M.Sc., F.E.S., Foreign Member of the Association of Economic Entomologists, Washington, U.S.A., and Special Lecturer on Economic Zoology in the University of Birmingham.

Stored grain, and particularly barley, when attacked by insects is generally said to be " weevilled," and although two species of weevil do considerable damage to grain when in store, there are upwards of 30 other insects in this country which are the cause of serious damage and loss. Miss Ormerod (11/A Reportof Observations of Injurious Insects, 1888, p. 75) records some observations from a correspondent who states, " in SOME INSECTS INJURIOUS TO BAULKY AND OTHER GUAIN. 243

the winter of 1884—85 wo lost between £1,000 and £2,000 on a single cargo of Russian wheat" by C'alandra gramria. Kirby and Spence also make frequent reference to individual losses, as do other writers. It may bo pointed out in passing that the number of species and of individuals which are found in stored grain in this country have for some years been steadily increasing, this is partly due, no doubt, to the apathy of certain millowners, maltsters, and others who will not take proper preventive and remedial measures, and also to the higher and more equal temperature maintained in modorn mills. Some account, therefore, of the life-histories of the commoner species met with, the problems encountered in endeavouring to reduce the loss they occasion, and the means now employed for exterminating, wherever possible, may not be without interest.

List of Insects Destructive to Grain, etc., when in Store.

Atropos divinuloria, Fabr The Grain Louse. Tenebriodes maxiritaniciis, L The Cadelle. Silvanus surinamictis, L The Saw-toothed Grain . Minus fur, L The Brown Grain Beetle. Niplus holokucus, Fald. Niplus crenatus, Fabr. affine, Boield. Gibbium scotias, Fabr. molitor, L The Yellow Meal-worm. , L The Dark Meal-worm. Alphiiobius diaperinus, Panz. Alphitobius piceus, 01. Gnafhocerus cornulus, Fabr The Broad-horned . Gnalhocerus maxillosus, Fabr The Slender-horned Flour Beetle. feirugineum, Fabr Tho Rust . Tribolium confusum, Duv The . meiinus, Herbst. Lathdiais oryzce, Wat. Calandra (Silopkilus) granaria, L. The Grain Weevil. Calandra(Sitophilm) oryzm, L. ... The Rice Weevil. Plodia interpundella, Hbn The Indian Meal Moth. Epheslia kuehniclla, Zell Tho Mediterranean Flour Moth. Pyralis farinalis, L The Meal Moth. SUrotroga ccrealella, 01 The Angoumois Grain Moth. Tinea granella,L The Wolf Moth. 244 COLLINGE: SOME INSECTS INJURIOUS TO

Atropos divinatoria, Fabr.—The Grain Louse.

This is a small, wingless, louse-like creature, with well- developed mouth organs, and an omnivorous feeder. During the past fow years it has been forwarded to me in samples of malt, which literally swarmed with these minuto insects. Generally speaking, it seldom occurs in this country in sufficient numbers to constitute a . It is common in most houses, feeding on the starchy piste used by paperhangers and that used by bookbinders.

Tenehriodes maurttaniais, L.—The Caddie.

The name Cadellc was given lo the of this insect many years ago by the French, it was originally described, however, in 1758. It stands by itself amongst grain-feeding insects in that both the larva and beetle attack and destroy any othor grain insects they may meet with. For a long time it was claimed that this beetle was carnivorous, but later observations have shown that it is both herbivorous and pre- daceous. There is only one brood in the year. Kirkup (Trans. Entom. Soc., 1812, 1, 329) records that- one found in a Spanish almond lived in the larval stage for 15 months, and remained alive as a beetle for a year and nine months. They are omnivorous feeders, in the larval condition passing from grain to grain, upon all of which they feed. The larva is a soft, fleshy, almost white grub, with short, scattered hairs, and the head dark brown, and there are two dark patches on the first three segments. Those in the first segment being most con spicuous. Tho last segment terminates in two dark, horny points. The pupa is almost white. The adult beetle is nearly black in colour and about a third of an inch in length.

Silvanus sunnumicus, L.—The Saw-toothed Grain Beetle.

A widely-distributed species, and common wherever grain is stored. Generally speaking, there are four broods in a year, but as in warm climates the whole life-cycle is completed in about 24 days, there may be as many as six or seven. In colder regions tho life-cycle occupies from six to ten weeks. The larva is somowhat flattonod, almost white, with slighter, darker BAULEY AND 0T1IEK CHAIN WHEN IN STOKE. 245

markings on each HOgmont. It has throo well-dovelopcd pairs of legs mid an abdominal prolcg, and is very active. When full fed it forms a covering consisting of small grains, etc., which it joins together by a sticky secretion, within this tho pupa is formed. The adult is about one-tenth of an inch in length, flattened, and of a chocolato-brown colour. Tho thorax is marked by two shallow, longitudinal grooves on the dorsal side, lateral to which are six saw-like teeth on each side.

Minus fin; L.—Tho Brown Grain Beetle.

This species haa frequently been recorded as damaging stored grain, although it is a general foedor upon decaying and vegetable

matter.

Xijrtus hololeucus, Fald.

Like the preceding species, this and X. crenatus, Fabr., are general feeders. Both have frequently been forwarded to mo damaging seeds.

Aiplus crcnatus, Fabr.

This is another beetle often found in old granaries. Although feeding mainly on wood, to which it does great damage, it has been clearly proved that it feeds on flour, which it damages to a large

extent. Mezium ajjine, Boield. Gilibium seolias, Fabr.

Occasionally found in grain.

Tenebrio moliior, L.—The Yellow Meal-worm.

This and the next species, and their larvae, the latter commonly termed " meal-worms," are amongst the largest of the attacking grain. The eggs are white and bean-shaped and about one-twentieth of an inch in length. They are deposited in flour, meal, and bran, particularly in bins. The larva looks not unlike a wire-worm; it is long, slender, and cylindrical, and about 1 inch in length. It is yellow in colour, becoming darker towards each joint, and there are two small anal spines. Tho pupa is pale ochreous. Tho adult beetle is a pitchy black above, ferruginous beneath, and a little over one-half of an inch 246 collinge: some insects injurious to in length. The eggs hatch in about 14 days. The lame appear in May and feed voraciously. They attain approximate growth in about three months and continue to feed until the following spring, when they change into pupae, in which condition they remain for about 14 days. There is a single brood only. The beetles are nocturnal in habit and strong fliers.

Tcnebrio obsairus, L.—The Dark Meal-worm. Very similar in form and habits to the preceding species. The larva, is pale brown and unlike T. moliloi; which prefers damp or damaged flour, meal, etc., this species exhibits a decided preference for dry, sound flour. Alphitobius diaperintts, Panz. Alphitdbhts piceus, 01. Two very small beetles which have probably been introduced into this country with grain.

Gnalhoccrus cormdus, Fabr.—The Broad-horned Flour Beetle. Gnulhocems maxillosius, Fabr.—The Slender-horned Flour Beetle. In prepared grain these two beetles are both very common.

Trihciium fcrrugineum, Fabr.—The Rust Red Flour Beetle. Tribolium confusum, Duv.—The Confused Flour Beetle. Next to the weevils these two insects are perhaps the most injurious we have to stored grain. They prefer prepared cereals, such as flour, oatmeal, malt, nuts, beans, peas, and almost any seeds. They are very similar in form and habits. The eggs, which are small white bodies, are attached to the sides of, or in cracks in, bins, barrels, etc. The larvae hatch out in from 6— 12 days and remain as such for from 24—36 days, they then change- to naked pupae and 6—12 days later the mature insects appear. In a high temperature, the life-cycle has been completed in 36 days and I have frequently seen it gone through in 56 days. There arc usually four broods in a year. Palorus melinus, Herbst. oryza?, Wat. Two very small beetles, measuring about 2i mm. in length. They occur in rice, flour, etc. BARLEY AND OTHER GRAIN WHEN IN STORE. 247

Calandra (Sitophilus) grunaria, L.—The Grain Weevil.

This is, perhaps, the commonest of grain bootlos, and it is annually becoming more and more troublesome. It is a very prolific species and, given suitable conditions, a single pair will produce many thousands of descendants in a year. The female deposits her eggs one in each grain, first puncturing the grain with the long, snout-like proboscis. Most recent authors state that tho grain is punctured by the proboscis of the female, who then deposits an egg and seals up the puncture. Olivier pointed out that the egg was laid on the outer surface. Fitch (Entom., 1879, p. 48) has also confirmed this. He states: " It has been usually supposed that the parent weevil bores with its rostrum into tho grain previous to depositing its egg in the hole made. I do not beliovo this is the case, for a very fine puncture only—such as would be made by a very fine needle—is to be seen on the borders of the germen in these grains which contain the larva." The number of eggs is variable, specimens kept in the laboratory deposited from 92—136 in a week and these hatched out in from 10— 1+ days. The actual time occupied in completing tho life-cycle is subject to great variation, duo to climate, otc, the average period is about 48 days, but I have frequently seen it completed in as few as 36 days. The number of generations in a year is variable, under favourable conditions there may be as many as five or six. The larva is a small, fleshy, legless grub, almost white in colour. The pupa is very similar in colour, but more transparent. The mature insect is a small dark brownish colourod beetle, having the head prolonged into a long snout or proboscis, at the end of which are tho mandibles and more posteriorly a pair of elbowed antennte or foolers. In this species the wings are not developed. In September, 1904, I received from a recently imported cargo of macaroni from Italy, large numbers of tho booties of this species. For the purposes of experiment, six lots were taken and placed in different sized glass jars and kept under varying conditions, which together with the results are briefly given below. Lot 1 consisted of 50 specimens kept on macaroni, they were nob supplied with any moisturo and the temperature varied from 50°— 60° F. At the end 18th day all the specimens wore dead. Lot 2 consisted of 20 specimens kept on barley at a temperature 248 COLLINGE: SOME INSECTS INJURIOUS TO averaging 80° F. They were placed in a tall jar with a damp sponge placed on a gauze plate. At the end of November, over 100 specimens were removed from the jar and a considerably larger numbor remained behind. Lot 3.—Infected barley only was placed in the jar early in October. The conditions were precisely the same as in Lot 2. By the middle of December, the whole life-cycle had been completed und the beetles were puiring. Lot 4.—Here the conditions were the same as in Lots 2 and 3, excepting that considerably less moisture was supplied. Ten beetles were introduced and 10 infected grains of barley amongst others in December, 1904. At the end of January, 1905, there were 19 beetles. It would thus appear that the larviu can hatch out with much less moisture. All the specimens were retained under those conditions until the end of June. No further breeding took place, but three of the specimens died. Lot 5 consisted of 20 specimens kept in maize, wheat, barley, oats, and macaroni. The temperature was about 70° F., and there was a free supply of moisture. Breeding took place freely and, at the end of June, 1905, there were some hundreds of specimens. An examina tion of the grain, etc., showed that there was a decided preference for lmrlcy both as food and for breeding in. Lot 6 consisted of 20 specimens placed in the jar in September, 1905. The temperature varied from 50°—56° F., and thore was u small quantity of moisture supplied. No breeding took placo. Two specimens died in March, three in April, five in May, six early in June, and three later, at the end of June only one remaining alive. Since theso experiments were carried out, Mr. Cole has published (Journ. of Econ. Biology, 1906, 1, 63) the results of n much more complete series of experiments than mine, on this species and the rico weevil, and has shown : 1. The influence of direct moisture at various temperatures. 2. The influence of indirect moisture or water vapour. 3. The effect of direct and indirect moisture on the developmental

stages. 4. The oirect of CO2, and 5. That of the deprivation of oxygen. Briefly, his results may be summarised as follows: BARLEY AND 0TI1KK CHAIN WHKN IN STORE. 249

1. That moisture, with the appropriate temperature (80° F.), is very favourable to thu adult insect; that the same temperature without moisture is fatal; and even if the temperaturo is below 80° F., the presence of moisture is capable of materially extending the life of the insects. 2. Here it was demonstrated that a non-ventilated atmosphero at about 80° F., charged with water vapour (no matter how poor in oxygen, and contaminated with carbonic acid gas), provides the most favourable conditions for the life and reproduction of these weevils. 3. Experiments show that direct moisture in the grain is detri mental to the developmental stages. 4. Cole showed that the weevils flourish exceedingly in a non- vontilated atmosphere, and as carbonic acid gas will accumulate in such an atmosphere, being given off both by the weevils themselves and also by the grain, whether germinating or not, it was important to test the weevils with this gas, which would naturally be given off in greater quantities in an incubator. "Ten rice weevils wero placed, at 10.37 A.M., in a glass vessel containing a pure atmosphere of thoroughly dried COj (i.e., no free oxygen). Temperaturo, 72° F. In half a minute all were apparently dead. They were taken out at 11.47 A.M., and although seemingly dead, they soon all rccovored. Returned to the jar at 12.30, and removed again at 4 p.m. By 4.30 fire were crawling about, and the other five were also living, but very quiet. Returned to the jar at 4.35. The next day (temperature, 73° F.) they were removed at 10 A.M., and were all dead. " In another experiment the weevils were placed in an atmosphere of CO2 and water vapour, but no free oxygen. Ten C. oryzw wore put in the mixture at 10.50 A.M., and removed at mid-day. All recovered in a short time. Returned at 12.15, and removed again at 4 p.m. By 4.30 several appeared to be coming to, but without waiting any further they were returned at 4.35 P.M. Removed the next day at 10 A.M., when all wero apparently quite dead. However, at 11 a.m. two recovered, at 11.30 a third, at 11.45 threo more, at 11.50 a seventh, at 12 an eighth, and by 12.45 all had recovered, and were fairly active." In subsequent experiments he "succeeded in keeping weevils alive for several days in a vioht atmosphere containing 80 per cent, of CO:. 250 COLMNGE: SOME INSECTS INJUIUOU8 TO

Whilst, therefore, pure dried CO-> is very fatal, acting, judging from my next series of experiments, either as a poison, or as a desiccator, or both, and not merely as an oxygen barrier, h mixture of the same gas with water vapour (still without free oxygen) is appreciably less fatal, thus adding one more testimony to the importance of moisture to these . Hence, also, almost any accumulation of CO2 in the atmosphere in which the weevils are living may bo disregarded as a preventive agent." 5. " If the weevils can flourish in a non-ventilated atmosphere, it is clearly important to ascertain how they bohavo in vticuo, and to what extent oxygen is necessary to their existence. It was here that I obtained my most remarkable results, as will be seen from the brief records of a few of my experiments below. In these I used a new double-action vacuum pump, fitted with a mercury barometer gauge. (1) "Ten C. oryzep. No moisture under bell-jar. Temperature varied from 67'—74° F. mercury of gauge reduced to 5 inches. On the third day three died, on the fourth day six, and by the seventh day all were dead. No feeding. (2) "An exact repetition of Experiment 1, except that a dish of water, from which all free oxygen in solution had been previously extracted, was placed under the bell-jar with tho crystallising dish containing the weevils, in order to provide a moist atmosphere. Temperature varied from 62°—76° F. Ten G. ory:ie. Mercury reduced to 5 inches. Feeding commenced on the third day, and there was one death then. On the fifth day three died, and an egg had been laid on one of the grains, but nothing came of it. On the 14th day copulation was observed, and on the 17th day there was a further death. The experiment was stopped on tho 23rd dny, when five of the weevils wcro still alive, and quite healthy and active, and five grains had been moro or less eaten. " These two experiments emphasise again the importance of moisture to grain weevils. In the first one it would have been concluded that the weevils died owing to the deprivation of oxygen, but the second experiment proves at once that the deaths were duo rather to the severe desiccation which would naturally be set up in the first case. (3) " Here tho moisture and food were combined in the form of slightly damp bread, of which tho weevils arn very fond, but which is largely forsaken when it dries. Ten C. wyza: Mercury reduced BARLEV AND OTHER GRAIN WHEN IN STORE. 251 to 1 inch! On the fourth day there were three deaths, on the 11th day there was another, and a further one on the 12th day. The experiment was stopped on the 15th day, when five of the weevils were still alive, and at once became very active on being removed from the pump. " The fact that fivo weovils out of 10 lived, fed, and even copulated for 23 days, at 5 inches of mercury, and that a similar number survived for 15 days at 1 inch is highly surprising, and indicates that the weevils, in what is now their state of nature, must often be called upon to live in an atmosphere rare in oxygen, and have thus become acclimatised to such a condition. In the face of these, and my other results, it would .bo absurd to hold either that weevils require a free play of air, or oven that free access to air, when possible, is favourable to their existence."

Calandra {SitophUus) oryza, L.—The Rice Weevil.

This species differs from the grain weevil in being dull brown in colour, in having the thorax densely pitted with round punctures, and the wing coses have four more or less distinct red spots. Further, unlike C. granaria, it possesses well-developed wings. Excepting that this species is often found in the field, and in warm climates lays its eggs in standing grain, its life-history does not materially differ from C. granaria.

Plodia interpunclella, Hbn.—The Indian Meal Moth.

Life-cycle occupies about fivo or six weeks, and there may be four, five, or even six generations in a year. The larvae spin large quantities of silken threads, with which they fasten together grain, seeds, etc., and, with this and thoir excrement, they often injure far more seed, grain, etc., than they actually consume.

Ephestia kuehniella, Zell.—The Mediterranean Flour Moth.

The history of this insect i3 of more than passing interest. Until 1877, when this moth was discovered in a flour mill at Halle, Germany, it was practically unknown. It was described by Zeller as a new species in 1879. It seems, however, that it was known to practical millers in France as early as 1840. In 1884 it was observed in Belgium, in 1885 in Holland, and in 1886 in England. Till then it 252 COLLIS'GB: SOME INSECTS INJURIOUS TO was thought to be an importation from America, but nothing was known of the insect until 1889, when it appeared in a mill in Ontario, Canada, later spreading to tho United States. There is fairly reliable evidence to show that the Mediterranean region was "probably its contre of dispersal. The eggs .are laid by night either singly or in chains of 8—10, a single female producing about 200 eggs. Fivo or six days are occupied in egg-laying, after which the female dies in a day or two. The eggs hatch in eight to nine days. At first the larvae are very tiny, 1 mm. in length, but in five to six weeks they become full grown, measuring i an inch. Like those of the preceding species, they spin fine silken threads. The cocoons are formed of silk mixed with flour.

Pyralis farinalis, L.—The Meal Moth.

The life-history of this tiny moth is at present unsatisfactory. The life-cycle is said to cover about eight weeks, and that there are four generations in a year. It prefers moist to dry conditions, and often does great damage to clamp grain, etc.

SUrotroiju cereaklla, 01.—The Angoumois Grain Moth.

The moth of this species deposits its eggs in standing grain as well as indoors in bins, etc. Tho eggs aro laid in clusters of from 20 to 30, and when first laid are perfectly white, soon they turn red, and in from four to seven days tho larva? appear and burrow into the kernels and feed on tho starchy matter. There are u number of generations, tho development being largely influenced by temperature. In the Southern States of America as many as eight generations have boen recorded.

Tinea grunella, L.—The Wolf Moth.

Oviposits in the grain in the field. Infests cereals of all kinds and passes from grain to grain, spinning them together in a web.

Parasites and Natural Enemies.

The increase of the different insects injurious to stored grain is to a small extent limited by certain parasites and natural enemies. Amongst the latter muy be mentioned spiders, mites, and cock- BARLEY AND OTHER GRAIN WHEN IN STOB.E. 253 roaches. Of the former there arc u considerable number of Hymenoptcrous insects.

Preventive anil Remedial Measures.

Any measures that will aid in keeping out the insects, or will lessen the means whereby suitable or favourable conditions for breeding are provided, are of the greatest importance. In this respect cleanliness is most important. In this country insufficient attention has as yet been given to the structure of granaries and other places whore grain, flour, seeds, etc., are stored. The windows that open in all flour mills Bhould be covered with fine wire gauze; by this means such pests as grain moths, and those beetles which fly at night, are effectually kept out. The doors of all rooms, warehouses, etc., should fit tightly, and should be so hung as to close themselves after being opened. Floors, walls, and ceilings should be smooth, and wherever possible concrete or metal work should be used in preference to wood. Thus floors should be of concrete and staircases, handrails, shafting, etc., of metal. In the United States of America, steel tanks are often used for the storage of grain. A temperature of 130°—140° F. is fatal to most insects, although the grain weevils, according to some observers, can withstand a much higher temperature. Of the various suggested remedies, fumigation with bisulphide of carbon seems to be the only really satisfactory one. The use of steam has been recommended. Most of the remedies of a ropellant nature have proved troublesome and ineffective, such, for instance, as salt, sulphur, naphthaline, etc. Fumigating with benzine and naphtha docs not always destroy the insects, and its odour is both offensive and persistent, whilst fumi gating with sulphur damages the machinery, the silk sieves in flour mills, and the grain or flour. Barley, I am informed, is specially injured by the use of sulphur. The only really effective fumigants I know of for the destruction of insect life are bisulphide of carbon and hydrocyanic acid, and the former is preferable wherever food substances are concerned. vot- iv.—3. T 254 SOME INSECTS INJURIOUS TO BARLEY AND OTHElt GRAIX.

Fumigation with Bisulphide of Carbon. ■

Wherever grain or any article used for purposes of food is attacked by insects, the simplest, most offoctivo, and inexpensive remedy is fumigation with bisulphide of carbon. It neither injures the edible or germinative qualities of grain or seed, unless left in the vapour for moro than 3G hours. It vaporises at ordinary temperatures, and is a most powerful poison. There are various ways of employing it, thus :— It may bo evaporated in vessels, or bo placed with grain in air-tight bins. Where small masses of material are infested, 1 oz. should be allowed for 100 lb. of material; for larger quantities, in the pro portion of 24 ozs. to the ton of grain. In buildings, 1 lb. to every 1,000 cubic feet of space should bo allowed. It is very important to remember that the fumes of this chemical, in addition to being deadly poison to all animal life, are also highly inflammable. No light—such, for instance, as a lighted cigar or pipe —should bo brought near it, nor should it bo used where there are electric wires or hot water pipes, unless theso have first been attended to. In the hands of a competent operator it is most effective, but highly dangerous in any other hands. Before commencing to fumigate, it is important that the room or building bo made us airtight as possible, and that one or more windows are left to open from the outside. Strips of paper, well sized, may be placed over the crevices of all doors and windows. Care should be taken to soo that no ono remains outsido the door of a room being treated, as in a passage, as some of the fumes may escape. Needless to say, no such animals as cats should be left in a mill, store, etc. After fumigating, which may last from five to 10 hours, the place treated should be well ventilated; also the fumigated goods. In conclusion, let me say that I shall at any time be pleased to receive examples of any insocts, in any stage, injurious to grain and other stored goods. Such material should bo sent in a tin box, with no holes in, and addressed to the University Department of Economic Zoology, 55, Nowhall Street, Birmingham. DISCUSSION. 255

Discussion.

Tho Chairman said ho was expressing tho feelings of ovoryone there in saying they had listened with a great deal of interest and pleasure to Mr. Collinge's paper. Possibly it did not furnish very many debatable points on which to raise a discussion, because the lecturer had confined himself in a great measure to the life history and habits of tho weevil and other injurious pests. Still, there must bo many members who could rolato experiences of their efforts to combat these injurious insects, which were capablo of doing an amount of damage altogether out of proportion to their size. He hoped they would not hesitate to unburden their minds. They could not be expected to look upon the weovil with tho benevolent eye of an ento mologist. They bought barley for commercial purposes, and were therefore more concerned in tho extermination of these pests than in their propagation. That portion of the paper wherein Mr. Collinge dealt with the means for recognising the presence of and the methods referred to for destroying them appealed strongly to the members. Several had boon mentioned. Screening, they know, was not entirely effectual. Tho burning of sulphur was effectual up to a certain point, particularly so, perhaps, when clearing empty malt bins; but a better and cleaner way of applying SO* was by means of cylinders of the liquefied gas, which was certainly effectual and easy to control and to handle. Carbon-bisulphide wus a dangerous to use in makings and grain stores on account of its extreme inflammability, and the odour it imparted was not a desirable ono to bring into contact with a material like malt, although Mr. Collingo had assured them that it was easily dissipated. He was led to understand that certain ports well known to grain merchants were seriously overrun with weevils. If that woro true, such ports must be a constant sourco of infection to grain passing through them, and it occurred to him during the reading of the paper tlmtour barley merchants might do themselves and the trade generally a good service if they would insist—as strongly as they well knew how to—upon the port authorities making some determined efforts to rid their warehouses of these troublesome and destructive insects. Ho threw this out as a suggestion, and should like to have an expression of opinion from the barley merchants present. Mr. F. II. Aulton said ho had listened to Mr. Collingo's very T 2 256 DISCUSSION. in tores ting papor with groat pleasure. There was no doubt it was one of the most serious questions the barley merchants and maltsters had to deal with, though most of the merchants present appeared to have been so extremely lucky as to have escaped being pestered with either weevil or moth. He quite agreed with Mr. Lones as to the necessity of dealing with the stores where barley was kept in the ports, but would also like to add stores at the railway stations and "hired sack depots." Some four years back ho (tho speaker) had been to a great deal of trouble in getting rid of weevil in some large barley stores, and then noticed the very first consignment of barley that camo in by rail was contaminated by weevil. As it was new Norfolk barley he was at a loss to understand how it could be so, until on going up to the station he found some 50 or 60 sacks of very badly infested maize stacked by the side of his barley. Ho immediately informed the railway company that if anything of tho sort occurred again he would refuse to accept delivery. Ho also considered that a quantity of weevil was spread about the country through hirod sacks. With regard to carbon bisulphide he would like to know how that could be got through a bin containing 800 or 1,000 qrs. of barley; would it go right through to tho bottom? With roforenco to the mills, Mr. Collinge had said he had seen 10 tons of infested matter removed from a small mill; was all that infested matter caused by the moths; would not some of it be ordinary mill dust? Ho had unfortunately had rather more experience in the habits of weevil than he cared for, and had tried various methods of exterminating them. He had put some in con centrated sulphuric and carbolic acid; they had lived for over five minutes in the acids. He had tried an advertised specific called weevil soap; some wero in this for half an half, others for two hours, and still wore able to walk away. The most effective destroyer ho ound was a 15-per-cent. solution of chloros, sprayed with a limowash sprayer. An ordinary whitewash brush did not get into the cracks. The spraying seemed very effective, and wherever there was a possible chance of getting behind the boards he had managed to get rid of them. Professor A. J. Brown said that the very interesting experiments described by Mr. Collingo, which showed that moisture favoured the development of the weevil, appeared to be very important from a discussion. 257 practical point of view. According to his own experience, however, he thought the amount of moisture required in some cases must he small, for he had observed propagation of weevils in samples of light foreign barley in his own laboratory which did not contain more than 12 per cent, of moisture. At one time he was under tho impression that the weevil was able to live in dry malt, and he had made experiments with malt which was quite dry, as woll as with malt containing the normal amount of 2 per cent, of moisturo ; apparently, however, the weevil could not live under these conditions. One occasionally did find them living in slack malt containing 8 per cent, or so of moisture. Even under these conditions tho amount of moisture seemed very small to support life, and it always appeared surprising to him how tho weevil could provide onough water for its needs. The larval form must contain 80 per cent, or so of water, and it seemed a puzzle how so much was obtained from the com paratively dry material on which it fed. One could see a possible indirect means of tho insect obtaining water, since, during the time it was feeding on tlio contents of tho grain, oxidation of part of the food supply to water as well as to carbonic acid took place. He should like to ask whether there was any reason to suppose that the insect was able to make use of this supply of water 1 Mr. Collinoe said that it had been demonstrated that it was able to do so. Professor Brown, continuing, said that with regard to tho method of egg-laying by tho weevil he gathered that the beetle commenced by eating a small hole in the corn, and, subsequently, after laying an egg in the hole sealed it up with some viscous material. He had looked for the eggs in grain, which he had reason to bolievo contained them, but could not find them. Mr. Collinge, ho know, possessed some special information with regard to this, and perhaps he would be good enough to tell them something about it. Ho would like to know also whether the adult insect actually ate tho grain ; he had always been under the impression that the adult insoct was not a feeder. Mr. Collinge said that it fed on grain. Professor Bkown inquired whether it attacked fresh grain. Mr. Collinoe roplied that it would attack fresh grain, and actually bore holes in it. 258 DISCUSSION.

Professor Brown asked whether, when carbon bisulphide was used, its vapour would penetrate a heap of barley lying on the floor some 2 or 3 feet deep. Mr. Collinge said that it would go through it in 24 hours ; in that time it would go through 6 or 7 feet deep. Professor Brown inquired if there was any possibility of using it in bins. Mr. Collinge replied in the affirmative. Professor Brown, continuing, said mention had been made of a small beetle, Tribolium. He remembered bringing Mr. Collinge a small beetle abounding in a local brewery some time ago, and he thought that it must be the species just referred to. Did it also lay its eggs in a similar way to the weevil 1 Mr. Collinge: "Not on the grain." Professor Brown : " Then it does not consume the whole of the contents of the grain like the weevil t" Mr. Collinge: "It feeds on the grain externally." Mr. H. C. A. Vine said he would like to ask a purely entomological question, viz., was anything of the nature of a " resting stage " to be found in the life history of the corn weevil 1 Such a stage was no doubt less likely to occur in the corn weevil than in some other species of the genus for, as far as we know, thore is no room in its life history for such an interval. But those who had to do with grain and malt knew that the beetle survived over periods of considerable duration, when no sustenance of any kind was available, and when the surround ings and atmospheric conditions were distinctly most unfavourable to its survival. When a store had apparently been completely freed from weevils and loft empty for months (during which weeks of exceedingly low winter temperature occurred) on tho introduction of perfectly clean malt fresh from kiln the beetle again made its appearance. Was it possible that its persistence was due to a "resting stage" such as was found in many insect cycles—the " American blight" (Schizoneura lanigera) on apple trees, for instance. He would also like to know whether the corn weevil was subject to tho attack of any internal parasite similar in nature to the attacks of the minute Ichneumonidoe upon the various species of aphides. Such parasitic attacks had continually saved crops from entire destruction by aphides, and he had himself observed instances whero over 50 per DISCUSSION. 259

«ent. of aphides had been destroyed by tho larvto of some parasite. In the corn weevil it seemed scarcely possiblo that the larvre could be get at by any insects that would, like thu Ichneumon or Ghalcid, pierce the skin with its ovipositor and lay an egg beneath, inasmuch as the weevil grub was protected by being within the grain, but never theless the opening by which tho weevil introduced its own egg might conceivably serve for the passage of the exceedingly minute ovipositor of a parasitic insect. If such an instance of parasitism were observed its close study and the development of the attacking insect might prove of the greatest value in the future. Mr. F. L. Talbot said that Professor Brown had made a remark that appealed to him very much when ho said that with the ordinary weevil it was impossible to see the corn in which tho larvae was deposited. But, especially in Mediterranean barley, there wore corns in which it was possible to get at the bottom and find a worm there. Those, he took it, wcro infected rather with tho Mediterranean moth than with the weevil. Mr. Collixge : " Oh, no! I think that is the weevil." Mr. Talbot, continuing, said he had frequently found corn in which it was possible to find at the bottom worms which could bo put under the microscope, and could be clearly seen, but they did get Mediterranean corn infected with the Mediterranean moth. Mr. Collinge : " I have never seen any. Whenever I have found infection it has been tho weevil." Mr. Talbot remarked that it was an almost certain fact in his experience that if they got a little crack in the walls where tho malt was stored against tho crack so that a littlo particle of the rain was driven through from outside in that part of the malt bin they found weevils. It was the same way with barley, if they got barley in juxtaposition to which thoro was moisture, the moisture would not damage tho corn to any considerable extont, but they would get weevil, and the barley would be therefore spoilt. Mr. B. Clifford said that with regard to the Tribolium or the Cadelle, he had found a sprinkling of these where there was an immense quantity of the other kind of weevils. Mr. Collinge : " I have frequently found it where there wore no other insects present." Mr. Clifford said ho had found tho Tribolium where there were 260 DISCUSSION. quantities of corn weevil, and lesser quantities of the saw-toothed grain beetle. Another beetle ho mentioned as having found was commonly known as the sugar beetle, the scientific name of which ha had for the moment forgotten. He had occasionally found that in barley on malting floors and on enclosing specimens in tins with good barloy found it damaged the barley. Ho would like to know if the floury matter, known in somo districts by the name of " Mother," found in odd spaces of malt-mills, and elevators, which, though it was of a very woolly nature, yet had no insect life in it, was due to the former presence of moth or weevil in the- grain ? Mr. Collinge: "It is probably composed of portions of tho silk and old cocoons of moths, most likely duo to Mediterranean floar moth." Mr. Clifford, continuing, said that everybody admitted that tho common corn weevil was generally found in foreign-brewing barleys, and seldom, if ever, did a parcel of English-grown barley introduce the weevil into a store. Moreover, this weevil, under ordinary cleanly conditions of store, did not increase, but rather slowly disappeared, apparently because our climate did not suit it. He thereforo con- sidorcd that the "infection" of a store by weevil was not so serious a mishap as was often supposed, by far tho greatest damage occurring to the parcel which originally contained the weevil. Like previous speakers, he had tried scores of times to find where the egg entered but had never succeeded. Mr. A. E. Buti.EK said he would like to ask Mr. Collinge if he had found any case whore barley had become infected by weevil in the vessels. He believed a considerable quantity of barloy was practically clean on the other side of the water, but when it got here it was " weevilled." Was this due to contamination in the vessel ? Ho would like to know further what temperature was fatal to the weevil, because he had noticed in kilns which were up to a temperature of 180° to 200° weevils in a state of activity. Mr. R. L. Siau said that carbon bisulphide had been most strongly recommended. Personally he should like to use it, but he saw one objection : it was so inllammable and explosive when mixed with air, and if their makings were to blow up in consequence of its use, would that be considered accidental, and would the insurance companies pay 1 Ho was afraid they would not, because they would hold its use was not DISCUSSION. 261 covered by the ordinary risk of a maltster. Perhaps Mr. Collingo might consult one or two of the insurance companies on tho point. Mr. Aui/roN wished to know whether Mr. Collingo said the weevils lived excluded from air ? Mr. Aui.ton, continuing, said he bad put some weevils in a largo, stoppered, glass bottlo, which was air-tight, and after a few days they appeared to be dead, but on taking out the stopper for a second or two, in a fow hours they appeared as lively as ever. Ho did that overy day for a month, and unless he let them have air they died. Mr. W. H. Evans said he should like to confirm what Mr. Talbot had said with roference to barleys from the Mediterranean districts which were commonly referred to as "fly-blown." Ho had seen samples whore there was an entire absence of weevil in which many corns were hollow. Ho was led to understand the egg was deposited in tho growing grain. He had understood that it was a kind of blight, but now he gathered that it was caused by weevils. It was strango that there should be no trace of weevil in tho grain. Ho would also like to know how long weevils could go without food 1 He noticed that when they came out of tho grain they did not last long. Thoy disappeared if there was no food about. Tho remedy for weovil was cloanlinoss. If thoir storage bins were properly constructed away from tho walls, thoy would have very little trouble from weevil. Wherever thoro was trouble they should look for defects, such as damp from cracks in tho wall. Another important point was to have sufficient air space between the bins. Nor did they propagate much when tho grain was stored in sacks and there was a proper circulation of air, they then developed very slowly. "When they had the misfortune to deal with weevil grain for some of their friends, they screened them out and cremated them immediately. He had seen weevils alive and kicking after having been submitted to a heat of 230° on tho kiln. Dry heat did not kill them. Mr. Aulton said ho had found thorn drop down on tho kiln at 150°. Mr. Evans : " But are thoy dead 1 I have found that after tho kiln had cooled down the weevil still alive in the morning." Mr. Aulton : " Thoy never go up again." Mr. Evans, continuing, said that Mr. Collinge had dealt only with a certain class of weevils, but he had noticed years ago a much larger 262 DISCUSSION. weevil, which affected beans, especially Egyptian beans. He had not had much experience of them of late years, but many j'ears ago his firm used to run a provender mill, and from time to time this weevil was met with in those beans; it was a much larger insect than the one found in barley, and was like a small woodlouse, and very horny. Mr. K. P. Taylor asked whether the weevil larva? could exhibit any life action after passing through the malting process. He said that he had found calcic bisulphite effective in killing the weevil. Immediately after its application the insects fell from wall or woodwork and wero proved dead. Carbolic acid solution also acted well, and might be used for painting oither walls or woodwork, but after allowing to thoroughly dry, a thick coat of whitewash should follow. He agreed with Mr. Evans that it was very much safer to storo grain in sack than in heap. Mr. Collinge replied, remarking that there was a somewhat for midable list of questions. With regard to the infection of the ports, that was a very important matter, and he thought those concerned in the buying of grain should be fully alive to that importance, and should take some measures to see that these places were properly inspected. As regarded the power of carbon-bisulphide, it had a great capacity for penetration, and would pass through fine flour to a considerable depth in 24 hours. A very suitable material for the propagation of insects was the fine dust which was likely to collect in spouts, boxes, etc. Professor Brown had raised the question as to barley and what happened to it after leaving the hold of the ship. Some doubt was expressed as to whether reproduction took place while on board. His own idea was that it actually took place in the hold of the ship. After leaving the ship there was considerable evaporation of water in the barley which dried in store, and in the hold there was every con dition in favour of reproduction, inasmuch as there was a certain amount of water in a stagnant atmosphere. It had been conclusively proved that a number of insects had the power of obtaining a certain amount of water by the splitting up of ccllulos and other substances. As to the method of egg laying, the weevils in nearly all cases adopted the plan of penetrating the grain by the mandibles at the end of the snout. The hole was driven by the proboscis; then the insect turned round and deposited the egg in the grain and, turning round again, sealed over the cavity. In Calandra the puncture is only slight, and DISCUSSION. 263 "

the larva oats its way into the grain. He had frequently taken the egg out and put the larvro under the microscope. The hole made was about .is large as a pin's point. If they took the grain and held it up to a strong light with a lens, although they would not see the actual larvie, they could see which was infected and which was not. There was something about the touch and the look of the grain where it was weovilled which differed from sound grain. With regard to the eating of the grain, the adult weevil certainly did cat a consider able quantity. He had no weevils at present, but he should be glad to have some, and the matter could easily be tested by putting 10 weevils with an ounce of grain, and seeing what quantity they •would eat in a given number of days. The beetle Tribolium also fed upon grain, and its habit was not to lay in the grain, but in tho cracks of tho bins and on the walls—in fact, almost anywhere. A further question related to tho resting stage in the life-history of the weovil. There was seldom such stage in the sense of a hiber nating period known to other insects, but if the temperature was lower than suited them, they would lie dormant for a considerable period. He hod kept some in macaroni for a year and five months. There was very littlo feeding, but they would creep out and go back. There was no breeding, v. A considerable number died, but quite half of them were alive at the end of the year and five months. The larvto of the corn weevil was not attacked by any large number of parasites. Probably some of the Hymenoptera described were well-known species under new names. America hod done a good deal in the study of parasites of insects, and it was still a fertile field for investigation. The corn with a grub at the bottom, he thought, was weovilled corn. Where he had found the larvra eating was where there was no sealing at all. It simply walked out by enlarging the actual puncture made by the female. Mills with insufficiently plastered walls, or where the plaster was allowed to fall away, although well whitewashed, were always more plentiful in yielding insects than mills with smooth walls. There was an indestructible paint which left a smooth surface, and did not allow insects to get on the walls. With regard to the Caddie, what he wished them to understand was that where he had found the Cadelle he had seldom found many other grain insects. In tho lost case he tried he got a fair number of Cadolles, but there were only a few specimens of 264 DISCUSSION.

Tribolium: The- sugar bootlo referred to ho did not know—at all ovents by that name. Ho would be glad to see it and to havo its scientific name. There were a large number of beetles affecting stored goods, but he had only mentioned those affecting corn, grain, and seeds. Thero was a ham and bacon beetle, a date beetle, a cigar beetle, etc., which they occasionally found on grain. One material mentioned, ho believed, was the silk, which was found with fine flour. Thoy could get it in considerable quantities, and it had the appearance of cotton wool. Experience differed, and while in some cases thoy might find not a single larva, in others thoy might find a great mass of thorn. With reference to the propagation, tomperature and moisture wore everything, and if thoy got the right temperature of 80° F., and supplied moisture, they had ideal conditions for propaga tion. As to whether contamination took place in the ship, it was certain that in very many cases it did. He had made many enquiries, and consulted people importing grain, and they told him that grain sent off in the ordinary way, which seemed to be in good condition, or, in which there might be a slight amount of weevil, was afterwards found in a bad state. It could not be altogether the conditions provided in the ship, having regard to the state in which the grain arrived, but thoro was no doubt that the ports, like the ships, were in a bad condition, and there again the grain should be treated with bisulphide of carbon. With regard to the questions arising with the insurunco companies, in connection with the use of bisulphide, he was not sufficiently acquainted, from the practical point of view, with malt to speak confidently, but it did not seem to him that there was the slightest difficulty if they kept the temperature down in administering bisulphido any more than in administering an antcs- thetic. He had never heard of a single case in which anything had gone wrong. He had corresponded with people who employed those fumigations, and apparently they had had no trouble. Professor Brown : " Is that in this country ?" Mr. Collinoe: "No, in Ireland and the United States." Con tinuing, ho said that thore were a large number of fumigations carried out there, and its use was very common. With regard to flies, thero were one or two injurious to grain, which got into the stem of the wheat, and other cereals. In tho United States they had discarded the practice of heaping grain, and were now DISCUSSION. 265 putting it all in large sacks. The practice was found to have a very beneficial effect. There were other species of weevil, but they generally spoke of the grain and the rice weevil, in connection with grain; most of the other weevils did not attack grain. With reference to the question raised by Mr. Talbot and other speakers as to the temperature at which the weevil would die, he had carried out some experiments, and he found that if the temperature were raised to 160° F. in nearly all cases the weevils died. A temperature of 135° F. was sufficient for the majority. The larvto certainly were all killed at 135°, and he made experiments with large quantities. It was in trying those experiments that he lost nearly all his weevils except the few already mentioned, which he kept for 17 months. He should be very glad to have any insects injurious to grain or stored products of any kind, such as household goods or packed goods, semolina, macaroni, or things of that character. Such insects wero very common in semolina, and he had samples in which quite 50 per oent. of the material consisted of the faeces of the larvso of the Indian meal moth. It was possible to separate the two quite distinctly, but that was purchased in quite an ordinary way in a grocer's shop. In some cases there were eggs, but there was no doubt about the existence of the actual insect, as the larvre had been reared from such material. The Chairman, in moving a vote of thanks to the lecturer, expressed the hope that the new Department of Economic Biology at the University would meet with the success it deserved. It was destined to have far-reaching and beneficial results to agriculture and kindred industries. From the manner in which Mr. Collingo had dealt with the subject, they must feel he was eminontly fitted to carry on the work of the department. Professor Brown seconded, and the resolution was carried. The compliment was briefly acknowledged by the lecturer.