100 



Observations on the various Insects 



Linnaeus, was abundant, skipping about the rotting potatoes, with 

 its beautiful iridescent scaly coat, and in the cavities were numbers 

 of a milk-white Ricinus, with multitudes of an ochreous Acarus 

 allied to A. coleoptratus.* M. Guerin also describes and figures 

 an Acarus called Glyciphagus fecularum,\ and another which he 

 names Tyroglyphus feculce, J both of which were found in the 

 changing potatoes or in cavities of the diseased tubers. 



The species, however, which I found most abundant upon them, 

 was the Acarus farince, which also swarms in meal and flour, 

 when kept for any length of time, especially in damp places, and 

 it is very remarkable that the same species seems to delight in 

 worm-eaten wine-corks, for they have been sent to me from many 

 cellars. In February, 1846, they were most abundant in decaying 

 potatoes, and in March, 1847, they were observed by the Rev. L. 

 Vernon Harcourt, near Chichester, and by Mr. Graham, of Cran- 

 ford. Being very white, they may swarm, as they often do in 

 flour, before they are discovered, and no doubt they feed upon 

 the starch and farinaceous portions of the potato. The mites vary 

 so greatly in their structure, that the old Genus Acarus has been 

 split into many Genera, and the one to which this species belongs 

 is now called 



26. Tyroglyphus farinae (fig. 46, magnified), being synony- 

 mous with the Acarus far in& of De Geer.§ It is like a minute 

 globule of fat, being of a pellucid shining white, with a rusty 

 cloud on the back of some specimens, and it is not larger than a 

 very small grain of sand (fig. q) : it is oval, the anus slightly con- 

 cave ; it has some longish rusty hairs scattered over the body, and 

 the head and legs are of the same colour : the thorax is small and 

 but slightly indicated ; the head and mouth form a horny cone : 

 the 8 legs are short, stout, and tapering, the 1st and 2nd pair 

 incline forward, the former arise close to the head, the latter are 

 attached to very large white scapes forming the base, the other 

 two pair are inserted at the middle of the belly and incline back- 

 ward ; they are all 6-jointed, the joints subquadrate or oblong, 

 pilose, the penultimate producing a few long bristles and 

 terminated by a strong hooked claw. 



They walk with tolerable alacrity and delight to burrow head 

 foremost into the flour. I have eaten pie-crust made of meal 

 in which myriads of these mites were generating, and found no ill 

 effects from the food. The meal was first spread on the top of 

 an oven to dry, by which process I found that a small degree of 

 heat killed them. 



* Gardeners' Chron., vol. iv. p. 316. 



f Bull, des Sean, de la Soc. Roy. et Cent. d'Agric, pi. 5, f. 7. 

 % Ibid., pi. 5, f. 9. 



$ Memoire de l'Hist. des Ins., vol. vii. p. 97, pi. 5, f. 15. 



