Mr. Wetherell said: Crows are greedy devourers of the white worm, which sometimes destroys acres of grass. As a grub eater, the crow deserves much praise. The crow is the scavenger of the bird family, eating anything and everything, whether it is sweet or carrion. The only quarrel I have with the crow is because it destroys the eggs and young birds.

Mr. Lockwood described the experience of a neighbor who planted corn after tarring it. This seemed to prevent the ravages of the crows until the second hoeing, when the corn was up some eighteen inches, at which time the crows came in and pulled nearly an acre clean.

Crows, said Dr. Riggs, have no crop, like a great many carnivorous birds. The passage leading from the mouth goes directly to the gizzard, something like the duck. The duck has no crop, yet the passage leading from the mouth to the gizzard in the duck becomes considerably enlarged. In the crow there is no enlargement of this passage, and everything passes directly into the gizzard, where it is digested.

Dr. Riggs had raised corn and watched the operations of the crows. Going upon the field in less than a minute after the crows had left it, he found they had pulled the corn, hill after hill, marching from one hill to the other. Not until the corn had become softened and had come up would they molest it. In the fall they would come in droves on to a field of corn, where it is in stacks, pick out the corn from the husks, and put it into their gizzards. They raid robbins' nests and swallows' nests, devouring eggs and young birds. Yet crows are great scavengers. In the spring they get a great many insects and moths from the ground, and do good work in picking up those large white grubs with red heads that work such destruction in some of our mowing fields.

Mr. Pratt stated that he had used coal tar on his seed corn for five or six years, and had never a spear pulled by the crows. Dr. Riggs never had known a crow to touch corn after it got to the second tier of leaves. Mr. Lockwood said crows would sample a whole field of corn to find corn not tarred. Mr. Pratt recommended to pour boiling water on the corn before applying the tar. A large tablespoonful of tar will color a pail of water.

According to Dr. Riggs, the hot mixture with the corn must be stirred continually; if not, the life of the corn will be killed and germination prevented. It may be poured on very hot, if the stirring is kept up and too much tar is not used. If the water is hot it will dissolve the tar, and as it is poured on it will coat every kernel of corn. If the water is allowed to stand upon the corn any great length of time, the chit of the corn will be damaged. The liquid should be poured off and the corn allowed to cool immediately after a good stirring.

Mr. Gold had known of crows pulling corn after the second hoeing, when the scare-crows had been removed from the field. The corn thus pulled had reached pretty good size. This pulling must have been done from sheer malice on the part of the crows.

Mr. Ayer was inclined to befriend the crow. For five years he had planted from eight to twelve acres of corn each year and had not lost twenty hills by crows. He does not use tar, but does not allow himself to go out of a newly-planted cornfield without first stretching a string around it on high poles and also providing a wind-mill with a little rattle box on it to make a noise. With him this practice keeps the crows away.

Mr. Goodwin thought crows were scavengers of the forests and did good service in destroying the worms, grubs, and insects that preyed upon our trees. He had raised some forty crops of corn, and whenever he had thoroughly twined it at the time of planting, crows did not pull it up. In damp spots, during the wet time and after his twine was down, he had known crows to pull up corn that was seven or eight inches high.

Respecting crows as insect eaters, Prof. Stearns admitted that they did devour insects; he had seen them eat insects on pear trees. Tame crows at his home had been watched while eating insects, yet a crow will eat corn a great deal quicker than he will eat insects.—Boston Cultivator.

* * * * *



THE PRAYING MANTIS AND ITS ALLIES.

On examining the strange forms shown in the accompanying engraving, many persons would suppose they were looking at exotic insects. Although this is true for many species of this group, which are indigenous to warm countries, and reach at the most only the southern temperate zone, yet there are certain of these insects that are beginning to be found in France, to the south of the Loire, and that are always too rare, since, being exclusively feeders on living prey, they prove useful aids to us.

These insects belong among the orthoptera—an order including species whose transformations are less complete than in other groups, and whose larval and pupal forms are very active, and closely resemble the imago. Two pairs of large wings characterize the adult state, the first pair of which are somewhat thickened to protect the broad, net-veined hinder pair, which fold up like a fan upon the abdomen. The hind legs are large and adapted for leaping.

The raptorial group called Mantid, which forms the subject of this article, includes species that maybe easily recognized by their large size, their enormous, spinous fore legs, which are adapted for seizing other insects, and from their devotional attitude when watching their prey.

These insects exhibit in general the phenomenon of mimicry, or adaptation for protection, through their color and form, some being green, like the plants upon which they live, others yellowish or grayish, and others brownish like dead leaves.

In the best known species, Mantis religiosa, the head is triangular, the eyes large, the prothorax very long, and the body narrowed and lengthened; the anterior feet are armed with hooks and spines, and the shanks are capable of being doubled up on the under side of the thighs. When at rest it sits upon the four posterior legs, with the head and prothorax nearly erect, and the anterior feet folded backward. The female insect attains a length of 54 millimeters, and the male only 40.

The color is of a handsome green, sometimes yellow, or of a yellowish red. The insects are slow in their motions, waiting on the branches of trees and shrubs for some other insect to pass within their reach, when they seize and hold it with the anterior feet, and tear it to pieces. They are very voracious, and sometimes prey upon each other. Their eggs are deposited in two long rows, protected by a parchment-like envelope, and attached to the stalk of a plant. The nymph is as voracious as the perfect insect, from which it differs principally in the less developed wings.

The devotional attitude of these insects when watching for their prey—their fore legs being elevated and joined in a supplicating manner—has given them in English the popular names of "soothsayer," "prophet," and "praying mantis," in French, "prie-Dieu," in Portuguese, "louva-Deos," etc. According to Sparmann, the Nubians and Hottentots regard mantides as tutelary divinities, and worship them as such. A monkish legend tells us that Saint Francis Xavier, having perceived a mantis holding its legs toward heaven, ordered it to sing the praises of God, when immediately the insect struck up one of the most exemplary of canticles! Pison, in his "Natural History of the East Indies," makes use of the word Vates (divine) to designate these insects, and speaks of that superstition, common to both Christians and heathens, that assigns to them the gifts of prophecy and divination. The habit that the mantis has of first stretching out one fore leg, and then the other, and of preserving such a position for some little time, has also led to the belief among the illiterate that it is in the act, in such cases, of pointing out the road to the passer by.



The old naturalist, Moufet, in his Theatrum Insectorum (London, 1634), says of the praying mantis (M. religiosa) that it is reported so divine that if a child asks his way of it, it will show him the right road by stretching out its leg, and that it will rarely or never deceive him.

This group of insects is most abundant in the tropical regions of Africa, South America, and India, but some species are found in the warmer parts of North America, Europe, and Australia. The American species is the "race-horse" (M. carolina), and occurs in the Southern and Western States. Burmeister says that M. argentina, of Buenos Ayres, seizes and eats small birds.

The genera allied to Mantis—Vates, Empusa, Harpax, and Schizocephala—occur in the tropics. The genus Eremophila inhabits the deserts of Northern Africa, where it resembles the sand in color.

The species shown in the engraving (which we borrow from La Nature) inhabit France.

* * * * *



MAY-FLIES.

There are usually found in the month of June, especially near water, certain insects that are called Ephemera, and which long ago acquired true celebrity, and furnished material for comparison to poets and philosophers. Indeed, in the adult state they live but one day, a fact that has given them their name. They appear for a few hours, fluttering about in the rays of a sun whose setting they are not to see, as they live during the space of a single twilight only. These insects have very short antenn, an imperfect mouth incapable of taking food, and delicate, gauze like wings, the posterior ones of which are always small, or even rudimentary or wanting. Their legs are very delicate—the anterior ones very long—and their abdomen terminates in two or three long articulated filaments. One character, which is unique among insects, is peculiar to Ephemerids; the adults issuing from the pupal envelope undergo still another moult in divesting themselves of a thin pellicle that covers the body, wings, and other appendages. This is what is called the subimago, and precedes the imago or perfect state of the insect. The short life of adult May-flies is, with most of them, passed in a continual state of agitation. They are seen rising vertically in a straight line, their long fore-legs stretched out like antenn, and serving to balance the posterior part of the body and the filaments of the abdomen during flight. On reaching a certain height they allow themselves to descend, stretching out while doing so their long wings and tail, which then serve as a parachute. Then a rapid working of these organs suddenly changes the direction of the motion, and they begin to ascend again. Coupling takes place during these aerial dances. Soon afterward the females approach the surface of the water and lay therein their eggs, spreading them out the while with the caudal filaments, or else depositing them all together in one mass that falls to the bottom.

These insects seek the light, and are attracted by an artificial one, describing concentric circles around it and finally falling into it and being burnt up. Their bodies on falling into the water constitute a food which is eagerly sought by fishes, and which is made use of by fishermen as a bait.

But the above is not the only state of Ephemerids, for their entire existence really lasts a year. Linnus has thus summed up the total life of these little creatures: "The larv swim in water; and, in becoming winged insects, have only the shortest kind of joy, for they often celebrate in a single day their wedding, parturition, and funeral obsequies." The eggs, in fact, give birth to more or less elongated larv, which are always provided with three filaments at the end of the abdomen, and which breathe the oxygen dissolved in the water by tracheo-branchi along the sides of the body. They are carnivorous, and live on small animal prey. The most recent authors who have studied them are Mr. Eaton, in England, and Mr. Vayssiere, of the Faculte des Sciences, at Marseilles.

A propos of the larv of Ephemera or May-flies, we must speak of one of the entomological rarities of France, the nature and zoological place of which it has taken more than a century to demonstrate. Geoffroy, the old historian of the insects of the vicinity of Paris, was the first to find in the waters of the Seine a small animal resembling one of the Daphnids. This animal has six short and slender thoracic legs, which terminate in a hook and are borne on the under side of the cephalic shield. This latter is provided above with two slender six-jointed antenn, two very large faceted eyes at the side, and three ocelli forming a triangle. The large thoraceo-abdominal shield is hollowed out behind into two movable valves which cover the first five segments of the abdomen (Fig. 1). The last four segments, of decreasing breadth, are retractile beneath the carapax, as is also the broad plume that terminates them, and which is formed of three short, transparent, and elegantly ciliated bristles. These are the locomotive organs of the animal, whose total length, with the segments of the tail expanded, does not exceed seven to eight millimeters. The animal is found in running waters, at a depth of from half a meter to a meter and a half. It hides under stones of all sizes, and, as soon as it is touched, its first care is to fix itself by the breast to their rough surface, and then to swim off to a more quiet place. It fastens itself so firmly to the stone that it is necessary to pass a thin knife-blade under it in order to detach it.



Geoffroy, because of the two large eyes, and without paying attention to the ocelli, named this larva the "feather-tailed binocle." C. Dumeril, in 1876, found it again in pools that formed after rains, and named the creature (which is of a bluish color passing to red) the "pisciform binocle." Since then, this larva has been found in the Seine at Point-du-Jour, Bas-Meudon, and between Epone and Mantes. Latreille, in 1832, decided it to be a crustacean, and named it Prosopistoma foliaceum. In September, 1868, the animal was found at Toulouse by Dr. E. Joly in the nearly dry Garonne. Finally, in 1880, Mr. Vayssiere met with it in abundance in the Rhone, near Avignon.

The abnormal existence of a six-legged crustacean occupied the attention of naturalists considerably. In 1869, Messrs. N. and E. Joly demonstrated that the famous "feather-tailed binocle" was the larva of an insect. They found in its mouth the buccal pieces of the Neuroptera, and, under the carapax, five pairs of branchial tufts attached to the segments that are invisible outwardly. Inside the animal were found trache, the digestic tube of an insect, and malpighian canals. Finally, in June, 1880, Mr. Vayssire was enabled to establish the fact definitely that the insect belonged among the Ephemerids. Two of the larvae that he raised in water became, from yellowish, gradually brown. Then they crawled up a stone partially out of water, the carapax gradually split, and the adults readily issued therefrom—the head first, then the legs, and finally the abdomen. At the same time, the wings, which were in three folds in the direction of their length, spread out in their definite form (Fig. 2). The insects finally flew away to alight at a distance from the water. The wings of the insect, which are of an iron gray, are covered with a down of fine hairs. The posterior ones soon disappear.



Perhaps the subimago in this genus of Ephemerids, as in certain others, is the permanent aerial state of the female.—La Nature.

* * * * *

Connecticut is rapidly advancing in the cultivation of oysters. About 90,000 acres are now planted, and thirty steamers and many sailing vessels are engaged in the trade.

* * * * *



THE COLOR OF WATER.

It is well known that the water of different lakes and rivers differs in color. The Mediterranean Sea is indigo blue, the ocean sky blue, Lake Geneva is azure, while the Lake of the Four Forest Cantons and Lake Constance, in Switzerland, as well as the river Rhine, are chrome green, and Kloenthaler Lake is grass green.

Tyndall thought that the blue color of water had a similar cause as the blue color of the air, being blue by reflected light and red by transmitted light. W. Spring has recently communicated to the Belgian Academy the results of his investigations upon the color of water. He proved that perfectly pure water in a tube 10 meters long had a distinctly blue color, while it ought, according to Tyndall, to look red. Spring also showed that water in which carbonate of lime, silica, clay, and salts were suspended in a fine state of division offered a resistance to the passage of light that was not inconsiderable. Since the red and violet light of the spectrum are much more feeble than the yellow, the former will be completely absorbed, while the latter passes through, producing, with the blue of the water itself, different shades of green.

* * * * *

There is to be held in Paris this year, from the 1st to the 22d of July, an insect exhibition, organized by the Central Society of Agriculture and Insectology. It will include (1) useful insects; (2) their products, raw, and in the first transformations; (3) apparatus and instruments used in the preparation of these products; (4) injurious insects and the various processes for destroying them; (5) everything relating to insectology.

* * * * *

A catalogue, containing brief notices of many important scientific papers heretofore published in the SUPPLEMENT, may be had gratis at this office.

* * * * *



THE SCIENTIFIC AMERICAN SUPPLEMENT.

PUBLISHED WEEKLY.

TERMS OF SUBSCRIPTION, $5 A YEAR.

Sent by mail, postage prepaid, to subscribers in any part of the United States or Canada. Six dollars a year, sent, prepaid, to any foreign country.

All the back numbers of THE SUPPLEMENT, from the commencement, January 1, 1876, can be had. Price, 10 cents each.

All the back volumes of THE SUPPLEMENT can likewise be supplied. Two volumes are issued yearly. Price of each volume, $2.50, stitched in paper, or $3.50, bound in stiff covers.

COMBINED RATES—One copy of SCIENTIFIC AMERICAN and one copy of SCIENTIFIC AMERICAN SUPPLEMENT, one year, postpaid, $7.00.

A liberal discount to booksellers, news agents, and canvassers.

MUNN & CO., PUBLISHERS,

261 BROADWAY, NEW YORK, N. Y.

* * * * *



PATENTS.

In connection with the SCIENTIFIC AMERICAN, Messrs. MUNN & Co. are Solicitors of American and Foreign Patents, have had 38 years' experience, and now have the largest establishment in the world. Patents are obtained on the best terms.

A special notice is made in the SCIENTIFIC AMERICAN of all Inventions patented through this Agency, with the name and residence of the Patentee. By the immense circulation thus given, public attention is directed to the merits of the new patent, and sales or introduction often easily effected.

Any person who has made a new discovery or invention can ascertain, free of charge, whether a patent can probably be obtained, by writing to MUNN & Co.

We also send free our Hand Book about the Patent Laws, Patents, Caveats. Trade Marks, their costs, and how procured, with hints for procuring advances on inventions. Address

MUNN & CO., 261 BROADWAY, NEW YORK.

Branch Office, cor. F and 7th Sts., Washington, D. C.

THE END