HARDWICKE'S SCIENCE-GOSSIP. 



[Jan. 1, 18G9. 



as if paralyzed. After the meal is despatched and 

 the shrivelled-up skin of the mite is cast away, the 

 Cheyletus returns to the spot in the cell which it 

 has appropriated as its home, and prepares to 

 deposit an egg. Before and after doing this, it is at 

 great pains to spin threads (apparently from its 

 mouth) crossing each other in various directions at 

 one point, to prevent the egg rolling away from the 

 selected spot, and also to afford the young Cheyletus, 

 when hatched, some slight protection. The young 

 (as with acari hi general) have only six legs, and 

 they remain, for some little time after leaving r the 

 egg, under the shelter of the silken cords which 

 formed its support before it burst. 



The cheese-mites that were enclosed in the cell 

 with the adult Cheyleti, being hunger-pressed, 

 commenced their depredations on the eggs of their 



Fig. 2. Egg of Cheyletus, § in. and A eye-piece. 



enemies, and were so successful in this under- 

 taking that from the early part of December till 

 the end of January, when the mites were in much 

 diminished force, not one of the eggs of the Cheyleti, 

 though many were laid, was suffered- to hatch. 

 They all disappeared under the mandibles of the 

 cheese-mites, whose voracity till then I was not well 

 acquainted with. One even had the temerity to 

 attack an adult Cheyletus, and was successful in 

 the attempt. Somehow it got round to the rear of 

 its enemy, and, having thus obtained the advantage, 

 it made the most of its opportunity, by climbing 

 up and then cutting furrows in the unfortunate 

 prisoner's back, and transferring the fragments of 

 viscera to its own interior economy, till at last the 

 Cheyletus gave in, and submitted to its fate. After 

 the captor had glutted itself, it left the prey 

 quivering in agony, and waddled off. When I took 

 another glance, two hours afterwards, five other 

 cheese-mites were busily occupied clearing away 

 the remains of the feast, and they steadily persisted 

 till nothing but the horny feet and mandibles re- 

 mained. These they rejected ; and I observe they 

 always leave these parts uneaten after a cannibal 

 feast, which is not an unfrequent occurrence in the 

 life of our friend Acarus domesticus. 



About the middle of February the eggs of the 

 Cheyleti were hatching too rapidly for the cheese- 

 mites to keep down the race effectually, and it was 

 most interesting to witness the early development 

 of ferocity towards cheese-mites in the young Chey- 

 leti. They would attack individuals much larger 

 than themselves by gripping the cheese-mite's leg 

 fiercely, and keeping hold long enough to obtain 

 some slight nutriment from the juicy prey. In 

 almost all cases, however, a few kicks compelled 



Fis 



3. Head of Cheyletus ; mandibles holding leg of 

 Cheese-mite, \ in. obj. 



the young tyrant, whose strength was not equal to 

 its desires, to relinquish its hold very soon. An 

 hour or two afterwards it would try again, and suc- 

 cessfully obtain some refreshment after a similar 

 struggle. Thus these little mites prolonged their 

 existence, and gradually grew larger. 



The conduct in confinement of this Cheyletus, 

 which, from comparison with Mr. Beck's drawings, 

 I take to be a distinct species from that he describes, 

 is probably just the same in its natural state. I 

 generally notice it in the dark cellar alluded to, 

 either in some crevice in certain pieces of wood, or 

 protected by an old forsaken spider's web ; and in 

 its neighbourhood I observe, often in considerable 

 numbers, an active species of mite, certainly not a 

 cheese-mite, but probably the species figured in 

 Hogg's book on the microscope as a flour-mite. 

 Occasionally I have caught a Cheyletus in the act 

 of making a meal off one of these. 



But it seems to me that the Cheyletus is by no 

 means restricted in its diet to one species of acarus, 

 for in confinement I have observed it devouring 

 several. Not long ago a person called my attention 

 to a large birdcage, which was much infested by 

 the bird -mite (Derma?iyssus avium). A close ex- 

 amination of the nests of that creature revealed a 

 mass of mites of all sizes, their cast skins and eggs, 



