Account of the Videx penetrans L. 297 



The male of. the sand flea is unknown. Fig. 42. repre- 

 sents a less swollen female, from beneath. By comparing 

 the sand flea with our common flea, we find that the for- 

 mer absolutely belongs to the genus Pulex, and is distin- 

 guished chiefly from the latter by its longer proboscis, and 

 by the anterior legs being placed nearer to the head. Some 

 specimens of the sand flea, extracted from the foot of a ne- 

 gro, differ from those of the dog's foot only by being black; 

 but they are accurately distinguished by both the natives and 

 the negroes ; the one w r e have described being called bicho 

 de cachorro (dog flea), and the latter merely bicho de pe. 

 When, in spite of the boots with which the feet may be pro- 

 tected, this little monster contrives to nestle in the foot, so soon 

 as any irritation is felt on the feet, nothing can be advised to be 

 more promptly done, than to cause them to be extracted from 

 the skin : otherwise, in less than twenty-four hours, a bag is 

 formed, in which some hundreds of eggs are contained ; and, 

 subsequently, the part ulcerates. The negroes are, in general, 

 the best operators; and they use for the purpose a little knife 

 or needle, by means of which the bag is carefully extracted. 

 If this should burst, the pupae fall out, and an ulcer ensues. 

 To prevent this, tobacco dust or juice, or lemon juice, or calo- 

 mel, is rubbed into the wound, and thus the pupae are killed. 

 But, should the nestled sand flea be entirely neglected, and 

 allowed to remain, the eggs develope themselves; a fearful 



loped in the abdomen of the mother, and pass there even the pupa state. 

 This can be distinctly observed, if a sand flea be extracted which has 

 nestled for some days : its abdomen has then increased to the size of a pea, 

 and one can clearly see the thorax, as well as proboscis and eyes, These 

 little bodies, found thus swollen, may rather be taken for pupae than for 

 eggs, for they are too large to be the latter. He further thinks that the 

 female of the sand flea feeds by suction the larva in her stomach, until it 

 has reached maturity : when a perfect insect, it may bite its way through ; 

 whence these insects must be classed amongst the viviparous. (Consult, also, 

 Neue Abhandlungen, &c, vol. ix. pt. 1. Leipz., 1789 ; in which, in p. 37., in an 

 extract from Olaus Swartz, Pulex penetrans L. is described and figured on 

 plate 2.) 



Professor Oken, in his Lehrbuch der Naturgesckichte, Jena, 1815, vol. iii. 

 p. 402., thinks the Pulex penetrans is no flea, since it does not change into 

 the pupa, and that it probably belongs to the ^4'cari; in favour of which its 

 mode of life, its instincts, and nestling propensities speak. 



[Mr. Westwood has informed us that the late Rev. Lansdown Guilding 

 had treated of this animal in unpublished MSS. of his, and that he had 

 applied to it the generic name of Sarcophaga, and that it certainly is one of 

 the Pulicidae. 



In V. p. 480. is a short notice on the habits of the chigo, as it is there 

 named, by William Sells, Esq., who has there remarked, " The chigo, I 

 apprehend, is a species of ^'carus."] 



Vol. IX. — No. 62. z 



