INSECTS INJURIOUS TO VEGETABLES AND ANIMALS. 



513 



Horses must have observed the great relief that 

 is given to the Horse witli corns when this an- 

 gle is pared out, and yet from some fatality, tlie 

 smith rarely leaves it where Kature placed it, 

 but cuts away every portion of it. 



Tiie true function of the frog is easily under- 

 stood. It gives security to the tread, and con- 

 tributes expansion to the hods: but the smith, 

 although the.se cases come before him every da^', 

 socnis 10 be quite unaware of the course which lie 

 should pursue, and cither leaves the frog almo.st 

 untouched, and then it becomes bruist,-d and in- 

 jured, or he pares it away so that it cannot come 

 into contact with the ground, and consequently 

 is not enabled to do its duty. 



The owner of the Horse will therefore find it 

 his interest occasionally to visit the forge, and 

 guided by the simple principles which have 



been stated, he will seldom eiT in his opinion of 

 what is going forward there. He should im- 

 press two principles deeply on his mind, that a 

 great deal more depends on the paring out of 

 the foot than in the construction of the shoe : 

 that few shoes, except they press upon the sole, 

 or arc made sliamefully bad, will lame the Horse, 

 but that he may be very easily lamed by au ig- 

 norant or improper paring out of the foot. 



Where the owner of the Hor.se has sufficient 

 influence with the smith, he will find it advisa- 

 ble ^always to have a few sets of shoes ready 

 made. Much time will be saved, in ca.so of ac- 

 cident, and there will not be, as is too often the 

 case, the cutting and paring and injuring of the 

 foot, in order to make it lit the .shoe. More in- 

 jiny than would be readily believed is done to 

 the foot by contriving to get on it too small a shoe. 



INSECTS MOST INJURIOUS TO VEGETABLES AND ANIMALS, 



AND THE MEANS BEST CALCULATED TO COUNTERACT THEIR RAVAGES 



BY REV. JAMES DUNCAN, M. W. S. 



[From the Joumal of the Highland Agricultural Society of Scotland.] 



Lice. — Almost all our domestic animals arc 

 well known to be more or less iirt'csted with 

 minute parasites, which have been long refer- 

 red by naturalists to the genus Pediculu.s. The 

 great majority of our native animal.s, whether 

 wild or in a domestic state, have their peculiar 

 kinds appropriated to them. Indeed, it was 

 long imagmed diat each and every animal had 

 its own pecu.iar parasite, but this is not alto- 

 gether borne out by facts ; for, 



"Although, in the miyonty of esses, a distinct spe- 

 cies of insect is found upon each particulnr Rnimal, 

 t". e. quadruped or bird, yet there are several instances 

 where the same kind infests three or four different 

 species of birds, but. in such exceptions, they arc al- 

 most always contined to individuals of the same gen- 

 era or family, or at .'cast to species of similar habits. 

 This is more strictly the case with birds than qxiad- 

 nipcds. Kor instance, Docopkorim icteroiilc.s 1 have 

 found on nearly every species of duck which has 

 come under my notice. 1 have received it from 

 other birdo nlsa ; but they were of aquatic habits, i 

 and belonging to the order Natal ores. The Nir- 

 mus obsciirus infests several species of sandpipers, I 

 eodwits, &.C. , the Nirmus rufus upon si.'voral :>( ihi: I 

 hawks and falcons; and i>wo/)/ior«s /(irj upon nearly 

 all the gulls. In the instances among quadrupeds it I 

 is rather doubtful whether the species is common to 

 two ditfercnt Hiiinials or not, or whether they may 

 not have been merely transferred by associating or 

 frequenting the same place of abode ; a? — for e.\am- 

 ple, the Trirkodir.les stalaris founil both upon the 

 ox and iiss — where the animals are feeding in the 

 same stall, or sleep together, a transfer of property 

 might easily be made. The Hmmatopinns pilifrfiis 

 infests dogs, and I have received specimens from the 

 fenct, which last animal was said to swarm with 

 them. Here it is rather difficult to account for the 

 occurrence, as I am luit aware that the two aninials 

 ever live on friendly terms with each other ; and. 

 mon!over, the person fiom whom I received them 

 informed me that he had not n dog. Wl.cn we ex- 

 tend our observations to genera, we find they take a 

 much wider range, and it is in only two or thn-e 

 ca.^es that we could with any confiilenee asseil that 

 they were diagnostic of certain families of Vertebra- 

 ta. It is easy to say whether. they are belonains to 

 quadrui>ed or bird, but Jnore dilficult to pronounce 

 the peculiar family of either, a.s seme genera of each 

 division ajjpear perfect cosmopolites , as, for instance, 

 (1037) 33 



the genus Pediculus of Linn., (since divided into Pe- 

 diculus and Ha-niatopinuis,) besides infesting man, 

 is also found in the orders Qiiadriimmia, on monkeys; 

 Rodeiitia, on the squirrel, hare, rabbit, water-rat; 

 Carnivnra, on the dog and seal ; Par.hijdcrmaln, on 

 the swine, ass and camel ; Ruvtinantia, on the deer, 

 ox, and butl'alo. The genus Nirmus, again, is very 

 extensively spread, infesting every order of birds 

 but the Gnllinacea:. Docophorus, all but Galliiia- 

 cen and Colmiibido: ; Lipeurus infesting the orders 

 Gnllinacra, Gratlo:, Palmipedes, and Arr.ipitres ; while, 

 on the other hand, a few, as I have stated, are nearly 

 certain indexes to the families. Eureum only on 

 Chelidoiies ; Trinoton only on Palmipedes; Gonioco- 

 tes and Goniodes only on Gallinacea and Columbidm ; 

 (tyropus only on the Guinea-pig in this countiy. J)r. 

 Burmeister enumerates a species also from ilie Ai, 

 (Bradypus Iridaclylits,) and, lastly, the genus Phthi- 

 rius on man,"* 



Not only are there numerous instances of one 

 kind of pedicular parasite being confined to one 

 kind of animal, but in not a few cases there is a 

 particular species assigned to differeiit parts of 

 the same animal, and these are seldom found to 

 encroach on their respective provinces. This 

 fact, in a physiological point of view, is exceed- 

 ingly curious, and difficult to be accounted for. 

 In Mr. Denny's beautiful woi'k, a quotation from 

 which has just been given, all the species hith- 

 erto found in this country are described and 

 figured in a style of art which has been seldom 

 surpassed as applied to entomological subjects. 

 He enumerates nearly 2.")0 different species as 

 occurring on Briti.sh animals. The great ma- 

 joritj- of these are found in too small numbers to 

 produce any injury of importance : but others, 

 again, as is well known to every one that rears 

 and fattens cattle, multiply excessively at times, 

 and are productive of great uneasiness and an- 

 noyance to the animals, while they greatly im- 

 pair their look by denuding the skin of the hair, 

 and giving it a very unsightly appearance. 



Naturalists differ in opinion as to whetlter 

 these insects undergo a true metamorphosis, like 

 others of their class. The truth appears to be, 



* " Denny's Monogiaphia Anoplurorum Britan- 

 nia!," p. ix. 



