458 



HISTORY OF INSECTS. 



Sweden, are said, by Linnaeus, to be very 

 large ; and he is of opinion that the head and 

 the body-louse differ in no respect from 

 each other. The phthiriasis, or lousy disease, 



The multiplication of these insects is unfortunately 

 far too great, but they are not quite so prolific as some 

 have represented. Experiments have proved that in six 

 days a louse can lay fifty eggs, and that some will still 

 remain in the belly. The young ones soon issue from 

 the eggs, (at the end of six days,) and change their skin 

 several times, after which, they are in a state to repro- 

 duce. This occurs about eighteen days after, when they 

 begin to lay in their turn. According to these observa- 

 tions, and the calculations to which they have given rise, 

 two female lice may have eighteen thousand descendants 

 in the course of two months. 



Linnaeus considered the louse, which remains con- 

 stantly on the human head, as a variety of the common 

 louse. It is, however, from its characters, and also 

 from its undeviating locality, proved to be a distinct 

 species. This same great naturalist also informs us, 

 that the largest lice he ever met with, are to be found 

 in the warm caverns of Fahlun, in Sweden. 



Children, and persons who totally neglect their hair, 

 and are otherwise of filthy habits, are generally infested 

 by the head-lice. When powder was fashionable, and 

 preposterously esteemed an embellishment to the hair, it 

 frequently proved a productive cause of these vermin. 

 Those who left too long upon their head the dandriff 

 produced by the use of powder, or who employed adul- 

 terated powder for the ornament of their hair, were very 

 liable to the intrusion of these unamiable guests. The 

 other species, which is found on all parts of the body, 

 excepting those of generation, comes generally in con- 

 sequence of the neglect of personal cleanliness, and the 

 not changing the linen and internal garments sufficiently 

 often. It is from this same species that those persons 

 suffer who are afflicted with that most dreadful and dis- 

 gusting malady phthiriasis. It may be observed that 

 their appearance, though in fewer numbers, is some- 

 times indicative of the approach, or even of the crisis of 

 other diseases, and that where there is no neglect of per- 

 sonal cleanliness. 



As for the third species, we believe, that its appear, 

 ance is invariably the result of indiscriminate debauch- 

 ery, accompanied of course with personal neglect. 



Dirt attracts these insects, and prepares for them a 

 nidus favourable to the reproduction of their posterity. 

 This is the vice which must be first eradicated if we are 

 desirous of being protected from their inroads, or if al- 

 ready attacked by them, of rendering more efficacious 

 any other means employed for their destruction. 



The remedies employed against these vermin act in 

 two ways. Some of them, such as oily and fatty sub- 

 stances, or such as contain azotic gas, close up the stig. 

 mata of these insects, or the apertures destined for the 

 admission of air, and smother them. Others, such as 

 the seeds of staphis agria, of larks-spur, tobacco, &c. 

 reduced to a powder, produce the effect of a violent 

 poison, and exercise their influence on the general or- 

 ganization of the animals. Mercurial preparations are, 

 of all others, the most certain arid speedy agents of their 

 destruction. They may also be employed for the ex- 

 tinction of the species which infest our domestic ani- 

 mals. 



It is said that lice, by piercing the skin, often produce 

 pustules which may be converted into itch or tinea. 

 Their multiplication, in certain subjects, is carried to 

 such an extent as to produce the mortal malady which 

 has been already noticed, namely, morbus pedicularis or 

 phthiriasis. History has afforded us many examples of 

 this ; Pherelima, mentioned by Herodotus ; Sylla, An- 

 tiochus Epiphanes, the two Herods, Maximin, and 



though very little known at present, was fre- 

 quent enough among the ancients : Herod, 

 Antiochus Epiphanes, Alcman the poet, Phe- 

 recydes, Cassander, Callisthenes, and Sylla, 



Philip the Second, perished of this disease, or something 

 very analogous to it. Mr Kirby is prone to think that 

 it has fallen particularly as a judgment from God on the 

 oppressors of mankind and the persecutors of religion. 

 But this and all such notions ought to be admitted with 

 caution, or rather rejected altogether. Until it is shown 

 that the disease in question has fallen upon such persons 

 alone, and on no others, we must discard the idea of its 

 being an instrument of Divine vengeance. But this is 

 so far from being the case, that the reverend entomo- 

 logist himself informs us that "this most loathsome of 

 all maladies, or one equally disgusting, has been the 

 inheritance of the rich, the wise, the noble, and the 

 mighty; and in the list of those who have fallen victims 

 to it, you will find poets, philosophers, princes, kings, 

 and emperors." It would be somewhat hard to believe 

 that among all these there was not one less bloody than 

 the first, or less profligate than the second Herod, less 

 oppressive than Maximin, or less bigotted than Philip. 

 The fact is, diseases of all kinds, like the rain of heaven, 

 fall upon the just and the unjust. They follow, to be 

 sure, as a pretty certain consequence, the indulgence in 

 some vices. Intemperance of all kinds will entail them 

 on the practiser as a necessary, but a natural punish- 

 ment. But the man who unites a sound constitution to 

 a prudent care of his health, may be at once supremely 

 wicked and remarkably healthy. He may cheat and 

 rob, and oppress and murder, but while he avoids the 

 vices which are ruinous to health, he is more likely to 

 find the reward of his villanies here from the indigna- 

 tion of mankind than from any heaven-descended visita- 

 tion of disease. 



Mr Kirby seems doubtful whether all the cases re- 

 corded as of morbus pedicularis are referrable to the 

 same specific cause. He believes there is sufficient 

 reason for thinking that three different kinds of insects 

 are concerned in the production of diseases which have 

 all been confounded under the name of phthiriasis. Be- 

 sides those produced by pediculi, this eminent naturalist 

 refers many cases to the agency of acari, or mites, and 

 larvae in general. 



It has never been proved, in any Avell authenticated 

 way, that the species of the genus pediculus burrow be- 

 neath the skin, or are subcutaneous. This remark is 

 equally applicable to man, and the lower animals, as far 

 as we know anything of the habits of the genus in ques- 

 tion. For this we have the highest medical authority, 

 as far as man is concerned. Dr Mead informs us that 

 "the louse feeds on the surface of the skin," and Dr 

 Willan, in a work on cutaneous diseases, states, respect- 

 ing the body-louse, that "the nits or eggs, are deposited 

 on the small hairs of the skin, and the animals are found 

 on the skin, or on the linen, and not under the cuticle, 

 as some authors have represented." The same writer 

 informs us, '* that many marvellous stories are related 

 by Forestus, Schenkius and others, respecting lice bred 

 under the skin, and discharged in swarms from absces- 

 ses, strumous ulcers, and vesications. The mode in 

 which pediculi are generated being now so well ascer- 

 tained, no credit can be given to these accounts." He 

 thinks, however, that those authors have mistaken some 

 other insects for lice, as some such animals may some- 

 times be found in putrid ulcers. 



It appears, therefore, that cases of disease from ani- 

 mals residing under the cuticle, cannot be referred to 

 pediculi. The poet Alcman, and Pherecydes Syrius, 

 the philosopher, are mentioned by Aristotle, as having 

 died of some complaint of this kind. But it could not 

 have been a true phthiriasis, as that great philosopher, 



