INSECTS INJURIOUS TO VEGETATION.* Tuts work, as it originally appeared

in 1841, formed one of a

-series of reports issued by the Commissioners oti the zoological and botanical survey of Massachusetts at the State expense, and its objects were defined by the following instructions given by Governor Elliot to Dr. Harris with the commission to undertake it (page 5) :—

"It is presumed to have been a leading object of the legislature, in authorizing this survey, to promote the agricultural benefit of the com- monwealth, and you will keep carefully in view the economical relations of every subject of your inquiry. By this, however, it is not intended that scientific order, method, or comprehension should be departed from. At the same time, that which is practically useful will receive a pro- portionally greater share of attention, than that which is merely curious, the promotion of comfort and happiness being the great human end of all science."

The author's own conception of the means by which the purpose of the Government might best be carried out, will appear by the following words with which he concludes his preface (page 6) :— " Believing that the aid of science tends greatly to improve the con- dition of any people engaged in agriculture and horticulture, and that these pursuits form the basis of our prosperity, and are the safeguards of our liberty and independence, I have felt it my duty, in treating the subject assigned to me, to endeavour to make it useful and acceptable to those persons whose honourable employment is the culture of the soil."

It is needful to explain thus clearly the origin and purpose of the work, in order to occupy a fair position in criticizing it. The reader, therefore, is to understand that, notwithstanding the formidable size and appearance of the volume, he must not expect a systematic treatise on entomology in general, or on

the entomology of the New England States, nor even an exhaus- tive account of the destructive insects of that region, but a work which, while accurate and scientific as far as it goes, is mainly

designed for the practical end of enabling farmers and gardeners

to distinguish their friends from their foes.

The intention of the Government in issuing such a commission as the above is, we think, highly creditable to the State, and the labour employed by Dr. Harris in carrying out its orders is equally creditable to him ; but if any of his readers are disposed

to doubt, before they begin to read his book, whether in such a subject as entomology the union of the scientific with the prac- tical, and, above all, the popular method of treatment, be possible,

we think their doubts will have culminated before they arrive at the end in the firm conviction that it is not so.

Doubtless there is as much difference between a farmer in Essex and a farmer in Massachusetts, as between a prize short- horn and a buffalo ; but the difference must be very much greater than this before we can believe that any considerable number of farmers anywhere could be found, who should read two pages in succession of the work before us. In point of fact, the task which Dr. Harris has set himself is impracticable. He has himself stated certain difficulties lying in the way of its execu- tion which he has entirely failed to surmount. These consist in the enormous number of insects to be described and the entire r impossibility of employing a popular nomenclature. On the latter subject, Dr. Harris tells us that entomology abounds In technical terms, owing to the excessive number of species of insects and the small size of many of them ; whence it results that few only have any popular name at all, and even of those few, many are most dissimilar creatures; massed together under the same name. Thus he says, "For example, the name weevil is given in this country to at least six different kinds of insects, two of which are moths, two are flies, and two are beetles."

It has followed, from the untoward conditions under which it has been composed, that Dr. Harris's book, though careful and laborious in no common degree, is at once too incomplete for a scientific treatise, and too minute and technical,—we may add too dry and unreadable, for a popular work.

But while we are compelled to speak of this work before us as likely to fail of its avowed purpose, we must not be supposed to undervalue it in certain other relations. Dr. Harris's contribu- * A Treatise on Some of the Insects Injurious to Vegetation. Harris, M.D. Boston: Crosby and Nichols. tions to entomology, in the shape of original observations and accounts of insects not previously described, are admitted by authorities in this country to be most valuable, and these are to be found for the most part in considerable detail in the present volume. It has, therefore, so far, no slight value to the scientific entomologist ; the descriptions are generally both clear and accurate.

As a specimen of Dr. Harris's style, and as likely also to interest our readers, we may extract the following description of the so-called " American " blight, the parentage of which, however, our author patriotically disowns for America (page 212) :— " There is now good reason to believe that the miscalled American blight is not indigenous to this country, and that it has been introduced here with fruit trees from Europe. Some persons, indeed, have supposed that it was not to be found here at all; but the late Mr. Buel has stated that it existed on his apple-trees, and I have once or twice seen it on apple- trees in Massachusetts, where, however, it still appears to be rare, and, consequently, I have not been able to examine the insects sufficiently myself. The best account that I have seen of them is contained in Knapp's 'Journal of a Naturalist,' from which, and from Haus- mann's description, the following observations are chiefly extracted :— The eggs of the woolly apple-tree louse are so small as not to be dis- tinguished without a microscope, and are enveloped in a cotton-like sub- stance, furnished by the body of the insect. They are deposited in the crotches of the branches, and in the chinks of the bark, at or near the surface of the ground, especially if there are suckers springing from the same place. The young, when first hatched, are covered with a very short and fine down, and appear in the spring of the year like little specks of mould on the trees. As the season advances and the insect increases in size, its downy coat becomes more distinct, and grows in length daily. This down is very easily removed, adheres to the fingers when it is touched, and seems to issue from all the pores of the skin of the abdomen. When fully grown, the insects of the first brood are one-tenth of an inch in length, and, when the down is rubbed off, the head, antennas, suckers, and shins are found to be of a blackish colour, and the abdomen honey-yellow. The young are pro- duced alive during the summer, are buried in masses of the down, and derive their nourishment from the sap of the ba:k and the alburnum, or young wood immediately under the bark.

"The adult insects never acquire wings, at least, such is the testimony of both Hausmann and Knapp, and are destitute of honey-tubes; but from time to time emit drops of a sticky fluid from the extremity of the body. These insects, though destitute of wings, are conveyed from tree to tree by means of their long down, which is so plentiful and so light as easily to be wafted by the winds of autumn, and thus the evil will gradually spread throughout an extensive orchard. The numerous punctures of these lice produce on the tender shoots a cellular appearance, and wherever a colony of them is established, worts or excrescences arise on the bark ; the limbs thus at tacked become sickly, the leaves turn yellow and drop off, and, as the infection spreads from limb to limb, the whole tree becomes diseased, and eventually perishes."

This extract may be taken as a fair specimen of the lighter and less detailed portions of' the book, and it is so, probably, for the very reason that the author is, avowedly, in this case, giving the results arrived at by others, rather than of his own obser- vation, and is, therefore, the less tempted to enter into minute description. It may be necessary, perhaps, to warn our non-scientific readers that the differences between English and

Massachusetts insects are by no means insignificant, and that, therefore, Dr. Harris's work, though highly valuable to scientific entomologists, is not suitable for a popular guide to the study of insects in this country. Amongst the coleoptera and orthoptera, especially, whole genera are to be found in New England which have no representatives here, and though many species of lepidop- tera in the two countries are indistinguishable by the most experienced entomologists, yet even among them many species are quite unlike.

The present edition seems to be the first which has been illustrated. The illustrations consist of eight coloured engrav- ings and numerous woodcuts, interspersed in the text, many of these being given on an enlarged scale, accompanied by a line representing the life-size of the animal. These have been engraved after drawings from nature made under the superin- tendence of Professor Lewis Agassiz, and are, as might be expected, admirable. It is only fair to add, in conclusion, that the book forms a handsome volume, and that its "bringing out" does great credit to the publishers, Messrs. Crosby and N'tchols, of Boston, its printing, paper, and other accessories leav- ing nothing to be desired, either for beauty or durability.