THE AMERICAN ENTOMOLOGIST. 



95 



ON OUR TABLE. 



Dr. J. T. C. Ratzebut'g's great work.s on 

 " Forest Trees, their Diseases and Insect Ene- 

 mies," and liis work on " Weeds of German)' 

 and Switzerland" — Die Waldverderhniss (23 

 Tlialer, gold) ; Die Standortsyewaichse tend 

 llnkraiuter Dentschlands und der Schiceitz (4i 

 Tlialer); and Die Waldverderber und Ihre 

 Feinde (i Thaler). — Some time since we re- 

 ceived from L. Agassiz, through Dr. llagen, of 

 Cambridge, the foregoing splendid German 

 works for inspection and notice. These works 

 have not their equal in the English language, 

 and with their superb illustrations and vast fund 

 of most desirable information, tlicy should have 

 a place in the library of every college where the 

 German language is taught. AVc would especi- 

 ally call the attention of the presidents of our 

 diflcrent agricultural colleges to these works. 

 The price of the three will probably cost over 

 $40.00 in America; but, in order to introduce 

 them into this country, the author has offered, 

 through his booksellers, to make a liberal de- 

 duction when more than one set is ordered, and 

 Dr. II. Ilagen, of Cambridge, Mass., has con- 

 sented to receive subscriptions. The books 

 were accompanied with the following notice 

 from the pen of the last named gentleman, 

 which we gladly make room for, as it contains 

 valuable suggestions, and we have ourselves 

 only found time to hastily glance over the 

 works : 



WooJ, aiul forests which prodiKC wood, form almost 

 as important a part of the natural wealth of a country 

 as do metals, coal, and other minerals. In some views 

 wood is even the more important article, since without 

 wood no culture is possiUe or imaijiiuihle. Wood cannot 

 in «/?;case3be replaced by iron orotlier Ijodies. Hence, 

 we find tliat the regions wliich are entirely or in part 

 destitute of wood never attain to a cultivated condi- 

 tion (large tracts of Africa, Asia, etc.), while, on the 

 other hand, a superabundance of forests forms an im- 

 pediment to cultivation, as in many parts of Americi. 

 It is only after the removal of this excess that cultiva- 

 tion progresses rapidly . Where nature oilers riches in 

 great abundance, there the due standard of apprecia- 

 tion becomes lost; and any one who has seen how the 

 IHississippi steamers, as well as the railroads in the 

 East and West, are often fed with timber that is valu- 

 able lor all purposes, will admit that this is an abuse, 

 or, in other words, that expensive materials are thus 

 wasted . Every waste , however, brings Its consequence, 

 and in time necessitates a supply at high rates. There 

 can be no doubt that in a country densely covered with 

 pristine woods, the clearing must precede cultivation, 

 and this clearing has to be carried on in the most rapid 

 anil most dcstrnctive manner, in order to prove profit- 

 able for the moment. Uut then, afterwards a period is 

 sure to arrive when a stop has to be put to that devasta- 

 tion, in order to forestall want. There can be no 



doubt that, in America, that time has come, or has 

 even been transgressed, though the fact has not yet be- 

 come very palpable^, for the reason that from other 

 parts, which are still well timbered, plenty of wood 

 can as yet be temporarily imported . A cessation of this 

 destructive practice is to be anticipated from an in- 

 creasing cheapness of coal as fuel for manufactories, 

 railroads, and steamboats; but this cessation will come 

 too late, in part, and generations to come will be sensi- 

 bly affected thereby; for itis a well known andvery im- 

 portant fact that the same kind of timber that existed on 

 a tract once cleared, cannot be immediately produccti 

 again. Nature has managed it so that quite a number 

 of processes of vegetation have to be gone through with 

 before the original trees of the primeval forest can re- 

 sume their rights. Under the tropics, as well as in 

 high northern latitudes, this change is wrought in the 

 course ol a few generations, but in the intermediate tem- 

 perate zones a much longer time is requiretl. Moreover, 

 the species that immetliately succeed those which were 

 cut down arc always such as furnish inferior wood. In 

 America, which is endowed by nature with agrcat num- 

 ber of species which afford the best wood for technical 

 purposes, this fact, no doubt, becomes the more iiiipor 

 tant. It appears to me that the very excellence of 

 American wood has essentially contributed to the rapid 

 advancement of civilization. A great number of skilled 

 pursuits are thereby essentially favored, since tlie firm- 

 ness and durability of its material admit of a delicacy 

 and care in their elaboration which, in Europe, is ren- 

 dered impracticable thi'ough the imperfection of their 

 wood . 



Add to this another circumstance— one which makes 

 this discussion suitable for the purposes of an entomolo- 

 gical paper: 



So long as nature alone is opeiating, it very rarely 

 (or peihaps never) occurs, tliat extensive damage to 

 plants and trees is wrought by insects or other animals. 

 It is only after the natural relations are altci'cd by hu- 

 man agencies, as, e. g.,hy tlie burning down or clearing 

 of entire tracts, or by a subsequent compulsory forest- 

 culture, that noxious insects are midtiplied in excess, 

 and require the energetic attention and interference of 

 mankind. We have lately had abundant proof of this 

 in Germany. The well-known Pine Koiubyx {Rovihy.r 

 Monucha) had been liaimless for about fifty years, when, 

 in IS.'ri, it reappeared. For three years little attciilioii 

 was paid to it, and interference was not attempted until 

 it had become too late. The result can only now, alter 

 the termination of the calamity, be l\illy estimated. 

 From the Ural mountains througli the entire width of 

 Kussia and Poland, and onward into the interior of 

 Prussia, 175,000 square miles were, in those years, in- 

 fested, and 5."),000,000 cords of wood destroyed. In 

 East Prussia alone (of the .size of the State of Massachu- 

 setts) 7,000,000 cords. I was myself an eye-witness to 

 interminable trains of butterflies on their way in search 

 of new brceding-phices. In several cases they passed 

 over sounds of fifteen miles' breadth in search of intact 

 forests. 



I believe that, in America, there exists no indepen- 

 dent literature on this subject, and no observations arc 

 on record. But it is quite plain that the experience of 

 other countries can be maile available. The climate of 

 JXirope is, in many respects, very similar to that ol the 

 most richly wooded northerly States of the Union . The 



