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THE PRACTICAL ENTOMOLOGIST. 



USE OF NATURAL HISTOEY. 



A correspondent of tlie Scientific American 

 paid a visit in 1S62, to Col. Pike, of Brooklyn, 

 N. Y., an amateur naturalist. During the visit, 

 the Colonel said : " I am very frequently asked 

 what is the use of this study of natural history. 

 Some of our very intelligent citizens say to me, 

 ' How are you going to make anything out of'this ? 

 What good does it do to catch butterflies?' Not 

 long ago, I saw one of the wealthiest men in Brook- 

 lyn at work on the trees in front of his house. He 

 had them all scraped and whitewashed at an ex- 

 pense of $80. Said I, ' Mr. Hunt, what are you 

 doing that for?' 'To keep off the worms,' he 

 said. 'That's no use,' I remarked. 'Oh,' said he, 

 'I think it is.' Well, now, the insect was a Geo- 

 ■niclra, or measuring-worm; the moth that pro- 

 ducas these worms, lays its eggs on the ends of the 

 branches, and it is almost impossible to kill the 

 eggs. The strongest Northwest winds have no 

 effect upon them ; I have seen them in Maine, and 

 it is difficult to crush them with your nail. When 

 they hatch in the spring, the young worm eats off 

 the tender leaves. You can judge what good the 

 scraping of the trunk would do. I went by some 

 months afterward, and Mr. Hunt was in front of 

 his house, looking up at his trees, which had not 

 a leaf on them, and I remarked, ' Your trees are 

 looking finely, Mr. Hunt ; the scraping was more 

 profitable than hunting butterflies.' " 



FIBE BLIGHT. 



A correspondent inclines to believe, that Down- 

 ing's Theory of Fire-blight, namely, that it is 

 caused by frozen sap, is the true one. There is a 

 remarkable fact which seems to show, that Down- 

 ing's Theory cannot be the true one. On the con- 

 tinent of Europe, they have, in many countries 

 where Pear and Apple-trees are commonly grown, 

 just as severe frosts as we have and just as sudden 

 changes in the weather. Yet there is no such 

 thing as Fire-blight known there. The same rea- 

 soning applies to another hypothesis, which has 

 been recently broached by Mr. Bennet, of Pitts- 

 burg, namely, that Fire-blight is caused by thun- 

 der and lightning. The foots seem to indicate that 

 it must be caused either by some insect peculiar to 

 America, or by some parasitic fungus peculiar to 

 America; for on no other supposition can we read- 

 ily explain, why it should not prevail in any part 

 of the Old World. 



If I may be allowed to hazard an opinion, or 

 rather a guess — what is known as '• Leaf-blight,'' 

 i. e. a vast number of dead, brown-colored spots on 

 the leaves, causing them to fall prematurely, is 

 produced by a ppile-green Leaf-hopper ( Chloroneu- 

 ra mahfica Walsh), of very nearly the same shape 

 and size as the Grape-vine Leaf-hopper, (figured 

 Pr.vctical Entomologist II, p. 51.) And 

 what is distinguished as " Frozen-sap Blight," is 

 produced by a minute parasitic fungus. But the 

 subject is a very difficult one, and requires further 

 and fuller investigation. B. D. W. 



ANSWERS TO CORRESPONDENTS. 



C. F. A., N. J. — In criticising an Article on Black- knot 

 which appeared in the last number of this Journal, (p. 

 6:i), you say that you have "examined the Black-knot 

 from the Wild Cherry, the Morello Cherry, and the cul- 

 tivated Phun, and published an account of it in the Ame- 

 rican Agriculturalist for March, 1863, and found it in all 

 cases to be identically the same Sphseria morbosa." 

 "The Wild Cherry!!" Even if you had not known it 

 before, you might have found out from the article which 

 you attempt to criticise, but which you have evidently 

 never read through, that there are no less than three 

 perfectly distinct kinds of Wild Cherry trees common to 

 the United States. I prefer not to accept as conclusive, 

 on so difficult a botanical subject as the identity of two 

 or three apparently distinct funguses, the evidence of a 

 Botanist who does not know that there is more than one 

 kind of Wild Cherry tree in America, or at all events 

 confounds together, under such indefinite phraseology as 

 '• TuE Wild Cherry," species which, in such a question as 

 this, ought to be carefully distinguished. 



As to your notion that what is mistaken for Black-knot 

 on cultivated cherries is almost universally caused by 

 firing with shot at the birds, and thus injuring the twigs, 

 Mr. Hicks informed me that he had not molested the birds 

 for years on his grounds, and yet it seems that his Cherry 

 trees were full of Biack-knot in 1860. Consequently this 

 strange new theory of yours will not hold water. Besides, 

 you say that people in your neighborhood " are constantly 

 complaining that they cannot raise any cherries because 

 of the knots, some of which are as large as a man's fist," 

 If then they do not raise any cherries, what occasion can 

 they possibly have to fire into their cherry trees? Are 

 they afraid that the robins will eat the black-knots ? 



Wm. Willock, N. Y. — The long rows of punctures, each 

 puncture cimtaining an elongated egg, on the twigs of the 

 Delaware grape-vine, are produced by the common Tree- 

 cricket {(Ecanthus nivctis). They are the same spoken of 

 in the Answer to J. M. Cole, of Missouri, Practical En- 

 tomologist, II, p. 74 ; and for advice what to do with 

 them, I must refer you to that Answer. The single grape 

 twig with several old scars on it, seems to have formerly 

 had the eggs of some Tree-hopper (Uembracis family) 

 deposited in it; but I cannot be sure of the fact in so old 

 a specimen. 



J. B. H., C. W. — The large moth expanding nearly 

 eight inches, which you hatched in a warm room from a 

 tough silken pod-like cocoon attached to the twig of an 

 apple-tree, can be nothing else but the Cccropia moth, 

 (Attacicscccropia), as you say that the body was "striped." 

 In this insect the abdomen is cross-barred with alternato 

 bands of white, black and red, while in the only other 

 common moths which are large enough to answer your 

 descripiion, (Attaciis polyphemus and A. /ujm), the abdo- 

 men is respectively ochre-yellow or white, without any 

 cross-bands. Its disappearance from the room iu which 

 it was confined, " leaving a portion of its wings neatly 

 cut off," was probably due to some mouse or rat having 

 made a meal of it. When hatched out in the natural 

 manner, this moth flies well enough with a lazy flapping 

 flight. The eggs it laid will produce nothing, as they 

 were not impregnated hy the male moth. You will find 

 excellent figures of this Insect and of its cocoon and pupa 

 in Harris's Injurious Insects, pp. 387-9. The " thick yel- 

 lowish jelly-like substance," found in the pupa that was 

 inside the other cocoon, is what is usually met with in 

 undeveloped pupje. 



M. W. Philips, Mississippi. — The s]>eclmehs of pear- 

 twigs •' varying in size from a pen-holder to a man's 

 thumb," from which the tip end had been severed by the 

 jaws of some insect, are, as you correctly remark, precisely 

 similar to oak-twigs omputated in th« same manner by 

 the Oak-pruner (Etaphidion putator). Whether similar 

 work which vou' have noticed on Hickory and on the 

 English or Wiiite Walnut, and which Dr. Fitch also no- 

 ticed on the Beech, be produced by the same species re- 

 mains to be proved. As there are several closely allied 

 species of Elaphidion, I should rather guess that each 

 distinct species confines it.self to a distinct tree : but pos- 

 sibly it m.ay not be so. The subject is well worth a care- 

 ful inquiry. 



