The Pea And Bean Beetles. Bruchus pisi. Linn. Bruchus granarius. Linn.

Fig. XVII.

1, Bruchus granarius, nat. size; 2, mag.; 9, Bruchus pisi, nat. size; 10, mag.; 4 and 5, larvæ;, nat. size, and mag; 6 and 7, pupa, nat. size and mag.; 11, pea with Bruchus pisi escaping; 3 and 8, beans attacked by Bruchus granarius.

In very many samples of peas and beans of all kinds there are some of the pulse which have tiny holes in them, with dark edges. If these pulse are split open with a knife it will be seen that the insides are more or less eaten away, scooped out as it were. In some cases, although there may be no holes in them, the pulse look unhealthy and not of a proper colour.

Upon opening these a maggot will be found which is evidently feeding upon the contents of the pulse. The best sorts of peas for podding grown by market gardeners, and for seeds-men by farmers, are frequently much injured in this way, and it has been noticed that the large and broad bean known as the Mazagan is often seriously affected. Winter beans are more page 58 liable to be attacked than those spring sown. Foreign peas and beans are worse as a rule than those grown in this country.

Though the embryos of the pulse are most generally left intact by the larvæ or maggots within them, the vitality of the seeds must be greatly impaired, and the plants from them, if indeed they are able to produce these, will be weakly, inasmuch as the supply of starch stored within the cotyledons for the support of the embryo and the young plant is diminished, and the other essential functions of the cotyledon are materially impaired.

Samples of peas and beans have been observed in which from twenty-five to thirty per cent, of the pulse had holes in them, showing their former occupation by the larvae of these beetles. Obviously there would be a serious loss of plants if these seeds were sown, and a serious diminution in food value if they were consumed by animals. These insects are very destructive in America and Canada, so that in some parts of the latter country peas and beans cannot be cultivated. Harris states that the Pea beetle is supposed to be a native of the United States, and that it may have been introduced from there into England.^*

Life History.

The perfect Pea beetle, Bruchus pisi (Nos. 9 and 10), is about two lines, or the sixth of an inch in length. It is of a dark colour, nearly black, with light coloured spots upon the elytra. Its wings are fairly large. The elytra do not cover the abdomen. The Bean beetle, Bruchus granarius (Nos. 1 and 2), is rather smaller than the Pea beetle and slightly different in colour, being of a more shiny black and without spots, or at least spots so pronounced, upon the elytra, which cover the abdomen more completely than those of the Bruchus pisi. The female beetles appear first in May, and deposit eggs in the blossoms of peas and beans as soon as they are formed. From these eggs small larvæ are hatched in a few days. These are without legs, of a dirty white colour, with black heads. They bore into the young peas and beans as they are developed, and live upon their substance. The larvæ change to pupae in the autumn, and remain within the peas and beans until the next spring, when they come forth as beetles.

In mild weather and in some circumstances they come forth much earlier.

Prevention.

Peas and beans intended for seed should be most carefully examined, and rejected if the samples contain any holes in them. page 59 In cases where it is suspected that pulse for seed is affected, it might be kiln dried, at a temperature not high enough to injure the germinating power.

Peas and beans, concerning which there are suspicions that they contain larvæ, though there may not at present be any holes in them, should be well winnowed or cleaned with special screens, so that the light insect-affected pulse may be taken out as much as possible.

Farmers and market gardeners should be especially careful to examine peas and beans and, indeed, seeds of all kinds before they sow them. Much direct disappointment and great losses are caused by sowing seeds injured by insect agency.

The Pea And Bean Weevils. Sitona crinita. Oliv. Sitono, lineata. Linn.

Fig. XVIII.

1 and 2, Sitona crinita nat. size and mag.; 3 and 4, Sitona lineata nat. size and mag.

These are two species of weevils very destructive to pulse crops. Farmers and gardeners have constantly noticed that the leaves of pea and bean plants are full of holes and notches, and so much so as to affect their growth most materially in some seasons. These weevils cause this and are most dangerous when the plants are young, commencing their depredations in March, or as soon as the weather becomes spring like, they work until the end of July.

It is said that they do not attack the common pea that is grown principally for pigs and sheep, but this is not correct, for complaints have been made from several parts showing that these have not by any means escaped. From observation it is clear that they eat all kinds of peas readily, in field and garden, as well as Mazagan, tick, and broad beans. In some seasons, and when the seed is sown late, they fairly prevent the plants from starting, eating off the leaves directly they appear from the cotyledons. A large grower of peas for seed reported that in 1883 he sustained considerable losses by the onslaughts of the pea weevils, especially upon the Early Sunrise sort.

Clover is much destroyed by these weevils, as well as by a closely allied and almost identical species, known as Sitona puncticollis. The weevils eat the leaves, and the grubs or larvæ devour the roots of the clover. In 1883 there were many complaints made of clover dying in patches in various parts of England in October. It was thought at first this was due to clover sickness, or to a fungus. Upon close examination small maggots were page 61 found at the roots, which were living upon the juicy succulent parts. Again, in the early spring following, the mischief was continued. Trifolium incarnatum is also attacked frequently. Plant is lost quickly and mysteriously. It is said that the "worm" is in it. In Kent, in 1882, this happened in a large piece of trifolium sown upon wheat stubble without ploughing. After the plants had nearly all disappeared the cause of the loss was traced to the larvæ of the Sitonæ.

Life History.

The perfect insect—Sitona lineata (Nos. 3 and 4)—is about four lines, or the third of an inch in length, rather narrow in shape. It is of an earthy colour, with light stripes or lines down its back. The head is dark coloured. The wings are large. Sitona crinita (Nos. 3 and 4) is hardly so large as the Sitona lineata, and is of a somewhat lighter colour, and without any stripes or lines, but has hairs or bristles on its body.

When disturbed these insects get on to the ground, either by falling or jumping, and remain perfectly still. Being similar in colour to the earth it is difficult to detect them. The eggs are white and numerous. The larvæ are found at the roots of clover plants from October until March, and of peas towards the end of May, and change to pupæ in the ground during June. The larvæ are nearly a quarter of an inch long, white, without legs, and having strong jaws.

Prevention.

After an attack the land should be cleaned from all rubbish and deeply ploughed at once, as the larvæ remain in the soil during the winter. A dressing of lime would be most advantageous in serious cases. Care should be taken not to sow another leguminous crop after an attack.

Clover fields literally swarm with these insects in some seasons. It would be highly dangerous to put peas, or beans, or tares in after clover in these circumstances, but this is an unusual course of cropping. As the weevils have been found in wheat stubbles after harvest, in land sown with wheat after clover, it is desirable not to put trifolium in after wheat without cultivation, as is often done. Trifolium crops have been materially injured by these Sitonæ.

Miss Ormerod recommends putting coal ashes saturated with soluble phenyle, diluted in the proportion of two table spoonfuls to ten gallons of water, into the drills or rows when peas and beans are sown. Ashes, sawdust, or earth saturated with paraffin would answer the same purpose, and might be used upon a large scale.

Remedies.

A dressing of two and a half cwts. of guano per acre has been found to help peas and beans suffering from the attacks of the Sitonæ. If put on early when the dew is on the plants, or after a slight shower, this manure sticks to the leaves, and renders them distasteful to the weevils, and helps the plants along at the same time. In market gardens, and in gardens, it is very efficacious to send men and boys to walk with a foot on either side of each row of plants, to press the earth tightly and firmly close to the plants in order to prevent the beetle from moving again easily. Many are killed by this process. This might be extended to larger cultivation, as a gang of men would get over a good deal of ground in a day. Horse hoeing cannot be done too often, and side hoeing will be found very useful.

The Pea Moth. Grapholitlia pisana. Curtis.

Fig. XIX.

1, larva on pea; 2, larva mag.; 3, moth nat. size; 4, moth mag.

It is very usual to find many of the peas in the pods at harvest time, and even while still green, half eaten, and surrounded with little particles of dust and dirt. In some instances as many as twenty per cent, are thus affected, to the great loss of weight and injury to the appearance of the samples. Much loss is sustained very frequently from this by seed-pea growers. Crops of valuable seed peas, worth from 10s. to 15s. per bushel, have been much injured by this pest in recent seasons in the pea fields in Kent, Essex, Surrey, Bedfordshire, and Lancashire, as well as in market garden farms, and in market gardens, and their value greatly reduced. The peas that are attacked cannot all be cleaned from the bulk, and buyers naturally think that the plants were unhealthy, and that it is dangerous to sow the seed. Sometimes the work of this moth is attributed to weevils and beetles, the Sitonæ and Bruchidæ. It is, however, entirely of a different character from this and is done at another period. This, insect is well known in France and Germany.

Life History.

This moth is a pretty little insect belonging to the family Tortricidæ. It is dusky grey in colour, with wings slightly tipped with white. It flies in the evening, and may often be seen in large numbers upon tares and sainfoin, though it has not been ascertained actually that it attacks these plants in the same way as peas. It places two or three eggs upon the young page 64 pods before the calices have fallen. From these pale green, rather inclining to yellow, caterpillars come and pierce their way into the pods, and then bore into the tender peas. They are about four lines long, or a little over a quarter of an inch, when full grown, having several pairs of legs. When the peas get hard the caterpillars fall to the ground, and getting below the surface enwrap themselves in silken cocoons, in which they remain until they change to pupæ in the spring. Some of the caterpillars remain in the pods and haulm and are carried with the peas.

Prevention.

Peas should not follow peas in the course of cropping on farms, or in market gardens and gardens, after an attack of this moth. After the peas have been carried in infested fields a horserake should collect the pieces of haulm left upon the ground, which should at once be burnt. The land must be deeply ploughed. When the peas are thrashed out at once it would be well to burn the "cavings" and rubbish; this should by no means be carried out to sheep in folds. In farms and market gardens where peas are picked green for market, it is important that infested haulm should be got off directly the peas are picked, and carted away or burnt. A good dressing of lime or lime ashes is a good means of prevention.

The Bean Aphis, Or Black Dolphin. Aphis Fabæ. Kirby and Spence. A. Rumicis. Linn.

Fig. XX.

1. Part of bean plant with aphides in situ; 2, male, mag.; 3, length and wing-breadth; 4, wingless female, mag.

Bean plants are often noticed to be swarming at their tops with black insects some time before they come into flower. Frequently these are so numerous as to prevent the plants from developing flowers, and if the flowers do struggle forth they produce but few beans, and these of a small stunted description. If the heads of the bean plants in fields badly attacked are examined they will be found covered with black aphides, whose beaks are thrust into the tissues of the stalks and leaves, from which they are sucking out the juice. The leaves and stems below them are covered with a viscous fluid. After a time this becomes black from the admixture of the excretions of the numerous insects. This filthy composition hinders, or absolutely checks, the respiration of the plants. With their sap exhausted by the myriad suckers, and their leaf and stem tissues choked up, the plants soon languish and die.

In the last season—1885—the crop in many bean fields was almost ruined by these aphides. The beans were few and small, and the haulm short and almost useless. A sickly odour went up from the infested plants, such as is smelt oftentimes in badly blighted hop gardens. It may be remarked here that almost every species of aphis was plentiful and unusually destructive in 1885. Plants of corn, fruit, hop, and vegetables, flowers, and page 66 shrubs, trees, and weeds were all more or less attacked and injured by their peculiar aphis pests. The circumstances of the winter and spring seasons appeared to suit their hibernation and propagation; while the weather of the spring with its more than usual variation of temperature rendered their plant food particularly pleasant to their tastes.

From the quantity of saccharine matter in the honey dew, or secretions of the aphides, it seems that a large or abnormal quantity of sugar in the composition of the sap of plants is necessary to encourage and sustain their attack. Alternations of temperature tend to increase the amount of sugar in the juices of plants. The more delicate and susceptible plants are more quickly, and in a greater degree, affected in this respect, and become infested with aphides whose progenitors have migrated from less attractive quarters. Thus the bean aphis, which is common to the dock (from whose Latin term Rumex it takes its name) as well as to the broom and furze, forsakes these plants and flies to the bean plant, and if the bean plant is in a suitable condition it remains and multiplies upon it.

Life History.

The perfect insect, the winged viviparous female, is quite black, of a somewhat shiny appearance. The male, which has wings, is also black.

Both larvæ—wingless viviparous females—and pupæ are at first of a lighter colour, but they soon become black.

At the end of the summer, or when the food supply has ceased, the generations of aphides are produced with wings and fly away to their winter retreats. Here they deposit wingless females, which lay eggs upon the leaves and in the axils of the leaves of the dock, broom, furze, thistle, borage, and other common plants, to be hatched out in the spring. From these eggs larvæ are hatched. These produce living larvæ endued with the power of reproducing living scions for several generations without coition. This parthenogenetic reproduction is continued for several generations. But when food fails, or is not appreciated, generations intervene having wings to carry them to fresh and more congenial plants. It appears that bean plants afford especially grateful food for these aphides, because in favourable circumstances they increase upon them with marvellous rapidity and soon ruin the crop; whereas upon their normal hosts—docks, thistles, broom, furze, and others—their ravages are seldom appreciable.

Prevention.

Docks and thistles must be religiously excluded from fields and hedge-rows bounding fields.

Remedies.

It is a frequent practice to top bean plants before they come into flower in order to make them throw out flowers low down the stems, and increase their fruitfulness. This should be done when aphides appear, but the leaves and tops thus cut off should be taken away. If they are left on the ground the larvæ will crawl up the stems. Horse hoeing would bury and destroy the greater part of them if the plants are set wide enough apart to permit this operation at so late a stage. Or the leaves and tops might be raked together with garden rakes, or picked up in baskets, and carried away.

In market gardens bean plants attacked by aphides may be washed with quassia, soft soap, and water in the proportion of four lbs. of soap, four lbs. of quassia to one hundred gallons of water, put on by means of hand syringes fitted in pails. This operation would be efficacious equally in large bean fields, but the difficulties and expense of application would be great.

The Pea Aphis. Aphis Pisi. Siphonophora Pisi. Buckton.

This is commonly called the "green dolphin," and frequently sadly injures pea plants. Like the black dolphin it is fostered upon common plants and weeds, as the Shepherd's purse, Capsella bursa pastoris, the common Nettle, and others. Its life history is the same as that of the bean aphis, and the sole means of prevention is the eradication of weeds from cultivated land and its neighbourhood as much as possible. Unfortunately there appear to be no remedies against this insect, or, at least, where peas are produced upon a large scale. In market gardens and ordinary gardens washing the affected plants with decoctions of quassia and soft soap, as recommended in the case of the bean aphis, might advantageously be adopted.

The Clover Weevil. Apion Apricans. Herbst.

Fig. XXI.

1, Weevil mag.; 2, nat. size; 5, larva mag.; 6, nat. size; 3, pupa mag.; 4, nat. size.

This weevil belongs to the genus Curculionidæ, called Apion because of its pear-like shape, and is included in this report as being very destructive to clover, one of the most important farm crops.

There are two or three different species of Apions all injurious to clover of various kinds, but their economy is practically the same, and the modes of attack and the treatment to be adopted are the same, so that it is only necessary to describe the typical species, viz., the Apion Apricans.

The modus operandi of this insect is to bore into the seeds of clover and eat their contents. Heads of clover may often be seen decaying, looking rusty, and losing the flowers prematurely. Upon investigation they will be found quite devoid of seeds, and small punctures will be found in the calices which contain or have contained the larvæ.

Not only does this Apion do harm in this manner in its larval form, it also eats the leaves of the clover plant in its perfect or weevil shape. Complaints of the clover leaves being eaten by "little black bugs" have been rife in parts of Kent as well as in other counties. Examination was duly made, and it was plain that the sources of the evil were indeed little dark coloured "bugs," Apion weevils. In the same fields they had eaten the clover to a serious extent in patches. It was the second cut, the first cut having been carried for seed. Upon looking at the heads of the seed clover it was found that many of these had not properly page 69 flowered, and showed clear signs of having been pierced by the larvæ of the Apions.

Life History.

The weevil is hardly more than the eighth of an inch long. In colour it is a very dark blue, with the upper parts of its legs a yellowish red colour. Its beak, as will be seen in the illustration, is very long indeed and slightly curved; it is terminated by strong jaws made for boring and biting. The weevils pair just before the clover blossoms, and the female lays her eggs within the blossoms, one at each place it is believed. Larvæ very small and of a dirty white hue are soon hatched from these, and bore into that part of the calyx which is close to the ovary, and consume the embryonic seeds. They lie curled up in the form shown at No. 5. They turn to pupæ and from this state at once become weevils, at least during the summer. At the end of the summer when the clover heads have vanished breeding ceases; then the weevils go to the ground and feed upon the leaves of the plants until the cold weather drives them to hiding places in the earth. They may be found on the outsides of clover stacks, and round these, having been carried thither with the flower stalks. It is supposed that it is only those that are on the outsides or a little way in the stalk that survive the heating process that takes place ordinarily in clover made into hay. In the case of clover cut for seed there is of course hardly any heat, and many weevils may be preserved in this manner.

Prevention.

Badly affected clover intended for hay should be put into a silo, where the fermentation would effectually settle the larvæ. Both first and second cuts should both be treated thus. Where seed clover is thrashed out all the refuse and flower heads knocked off should be burnt.

Remedies.

There appears to be no remedy against these weevils when at work in clover heads. When they are discovered eating the clover plants in the autumn, feeding and folding sheep upon the leys would check them.

The Dutch Clover Weevil. Apion flavipes. Kirby.

Another species of Apion—A. flavipes—injures Dutch clover. Another—A. livescerum, or A. Onobrychis-sainfoin; and yet another tares or vetches. The whole group of Papilionaceæ, indeed, are very liable to injuries from this family of insects.

C. W.