THE FARMERS' REGISTER. 



527 



reporter upon Mr. French's practice speaks with 

 surprise ol the rudeness of tiie roof oC liis Ibrciiitf- 

 houses, and of the numerous openings into the 

 air through the laps ot tlic glass and the joints ot 

 the sashes ; but these were points of no impor- 

 tance under the mode ol' management adopted. 



The imposibility of preserving any plants ex- 

 cept succulents, in a healthy state, lor any long 

 period, in a sitting-room, is evidently owing to the 

 impracticability of maintaining the atmosphere ol 

 euch a situation in a state of sullicient dampness. 



An excess of dampness is indispensable to 

 plants, in a state of rapid growth, partly because 

 it prevents the action of perspiration becoming 

 too violent, and partly because under such cir- 

 cumstances a considerable quantity of aqueous 

 food is absorbed from the atmosphere, in addition 

 _to that obtained by the roots. 



-But it is essential to observe that, when not in 

 a state of rapid growth, a large amount of moist- 

 ure in the air will be prejudicial rather than ad- 

 vantageous to a plant ; if the temperature is at 

 the same time high, excitability will remain in a 

 state of continued action, and that rest which 

 is necessary will be withheld, the result of 

 which will be an eventual destruction of the vital 

 energies. But, on the other hand, if the tem- 

 perature is kept low while the amount of atmo- 

 spherical moisture is considerable, the latter is 

 absorbed, without its being possible for the plant 

 to decompose it ; the system then becomes, in 

 the younger and more absorbent parts, distended 

 with water, and decomposition takes places, fol- 

 lowed by the appearance of a crop of microscopi- 

 cal ftingi ; in short, that appearance presents 

 itself which is technically called "damping ofi'." 



The skilful balancing of the temperature and 



blister flies for sale to the apothecaries. We 

 have observed, since writing the previous notice, 

 that some of the Hies have but one stripe on the 

 back, while others have three, by vvhicli we con- 

 je-(ure, the dilierent sexes might be discrimi- 

 naied. 



There are now two material remarks to make 

 upon the sulijecl of this destroyer. The first is 

 that his ravages may be arrested by the use of 

 lime, as directed in an excellent communication 

 from Mr. Pindell which we publish to-day ; and 

 the other is, that the destroyer himseli, may be 

 easily caught and made a profitable object of com- 

 merce. We have now recorded to opinions of 

 J)octors Mitchell, Parker and Martin, in favor of 

 the excellent qualities of the fly lor producino- 

 blisters. "^ 



Near Lexington, August lOth, 1841. 



Bear sir;— The article in your last number, 

 on blister flies, has claims to further notice. 

 They have completely riddled my sugar beets 

 and potato vines. They appear to preler the su- 

 gar beet, to the common kind, the latter being 

 comparatively but little injured. On examinatiorT, 

 alter reading your remarks, [ perceived consider- 

 able variety in the bugs, as 1 find them among 

 my beets. Some are almost entirely black, while 

 others have several yellow streaks, runnino- 

 lengthwise. They are all about three fourths 

 of an inch in length, do not attempt to fly, 

 but fall to the earth readily when the leaf is 

 shaken. 



The flies are all known as potato flies, because 

 found in patches of that vegetable, but they are 

 varieties of the genus cantharis. The species 

 already known amount to seven or eight, thoufh 



moisture of the air, in cultivating different kinds lour only 1 believe have been employed medi 



of plants, and the just adaptation of them to the cinally. 



various seasons of growth, constitute the most The most common species Ib the cantharis vit- 



complicated and difficult part of a gardener's art. tala, called also lytta vittata, potato fly, 8)-c. It 



There is some danger in laying down any general was first described in 1781 by a foreio-ner' but 



rules with respect to this subject, so much depends in 1S05, its properties were noticed in a° memoir 



upon the peculiar habits of species, of which the furnished by Dr. Isaac Chapman, of Bucks coun- 



mnflinPFlt inno arA onrtlfJac? If mci\r tir\uroi7or f t\7 Pc»nncii7li7o*-i!fi ; .^ #U„ XT "IT"-.-!- i*;i i- . ■-» 



modifications are endless. It may, however, I 

 think, be safely stated, that the following rules 

 deserve especial attention : — 



1. Most moisture in the air is demanded by 

 plants when they first begin to grow, and least 

 when their periodical growth is completed. 



2. The quantity of atmospheric moisture re- 

 quired by plants is, cceieris paribus, in inverse 

 proportion to the distance from the equator of the 

 countries which they naturally inhabit. 



3. Plants with annual stems require more than 

 those with ligneous stems. 



4. The amount of moisture in the air most sui- 

 table to plants at rest is in inverse proportion to 



ty, Pennsylvania, in the New York Medical Re- 

 pository, vol. 2d, page 163. During the last war, 

 Spanish flies rose to an extravagant price, and at 

 letigth could not be had at all, in some parts of the 

 country. This emergency led to the extensive 

 use of the potoio fly, above named, in the East- 

 ern hospitals, dispensaries, and in private prac- 

 tice. I made several trials of this American fly. 

 in 1811 and 1812, with entire satisfaction. 



Dr. Chapman caught the flies in a common 

 quart mug, which he placed in boiling water, to 

 destroy the vitality. He says, " as no difficulty at- 

 tends gathering them, children may be profitably 

 employed in the business, and as cantharides of- 



ihequantijyof aqueous matter i hey at that time ; ten sell at from ten to sixteen dollars per pound 



contain. (Hence the dryness of the air required 

 by succulent plants when at rest.) 



THE BLISTER FLY. 



From tlie Kentuclty Fanner. 



We are very much obliged to Professor Mit- 

 chell for the following ; and we think his remarks 

 go to encourage the suggestion we threw out, of 

 the propriety of employing children in gathering 



they will be an object worthy of attention.' 

 The ash colored fly, described first in 1801 by 11- 

 liger, I have not seen. It abounded in Massa- 

 chusetts in 1808, and excited a good deal of in- 

 terest m the medical profession. It infests the 

 potato vine, bean vines and wild indigo, and 

 some mistake it for the vittata, which is mainly 

 black, but has yellow lines on the breast and 

 back. 



The Cantharis marginate was examined by 

 the late Prof. Woodhouse, and afterwards by Dr. 

 Harris, of Massachusetts. It is black, with two 



