MOTIONS OF INSECTS. 459 



in different orders have them, and some in greater numbers. As I lately 

 observed, the foot-cushions of the Buprestes are something very like them. 



minutes were employed to make them so by stretching out her trunk, and passing 

 them repeatedly along its sides, apparently for the sake of moistening the flour and 

 causing its grains to adhere ; for after this- operation, on rubbing her tarsi together, 

 which she next proceeded to do, I saw distinct little pellets of flour fall down. A 

 process almost exactly similar I have always seen used by blue-bottle flies and 

 common house-flies which had their tarsi clogged with flour by walking over it, or 

 by having it dusted over them ; but these manoeuvres are required for an especial 

 purpose, and on ordinary occasions, as before observed, the object in rubbing the 

 tarsi together is not to clean them, but the pulvilli, for which they serve as brushes. 

 Besides rubbing the tarsi together, flies are often seen, while thus emploj'ed, to pass 

 the two fore tarsi and tibise with sudden jerks over the back of the head and eyes, 

 and the two hind tarsi and tibiae over and under the wings, and especially over their 

 outer margins, and occasionally also over the back of the abdomen. That one object 

 of these operations is often to clean these parts from dust I have no doubt, as on 

 powdering flies with flour they thus employ themselves, sometimes for ten minutes, 

 in detaching every part of it from their eyes, wings, and abdomen ; but I am also 

 inclined to believe that, in general, when this passing of the legs over the back of 

 the head and outer margin of the wings takes place in connection with the ordinary 

 rubbing of the tarsi together, as it usually does, that the object is rather for the 

 purpose of completing the entire cleansing of the tarsal brushes (for which the row 

 of strong hairs visible under a lens on the exterior margin of the wings seems well 

 adapted), so that they may act more perfectly on the pulvilli. Here, too, it should 

 be noticed, in proof of the importance of all the pulvilli being kept clean, that as 

 the tarsi of the two middle legs cannot be applied to each other, flies are constantly 

 in the habit of rubbing one of these tarsi and its pulvillus sometimes between the 

 two fore tarsi, and at other times between the two hind ones. I ought also not to 

 omit stating, that having taken out of a spider's net one of the minute Chakidida 

 just caught, and pulled away the threads attached to it, it spent some time in 

 passing its hinder tarsi over its wings and abdomen, and then in passing its fore 

 tarsi through its palpi, apparently, as in the case of flies, to clean its pulvilli from 

 any remains of the spider's net ; and that having surrounded a minute beetle {3Ieli- 

 gethes aneus), which chanced to be on the window, with a slight circle of moisture, 

 it was unable to pass through it, and repeatedly drew its wetted fore tarsi through 

 its mouth, and rubbed the hind tarsi together ; and that precisely the same results 

 took place in the case of an Ichneumon placed in similar circumstances, only it spent 

 much more time in rubbing both its fore and hind tarsi together after being wetted, 

 and in passing the former over its antennae and through its mouth ; and when 

 powdered with flour, it spent, like the flies before mentioned, some minutes in 

 cleaning itself by the same processes. 



Though the above observations, hastily made on the spur of the occasion since 

 beginning this note, seem to prove that it is necessary the pulvilli of flies and of 

 some other insects should be kept free from moisture and dust to enable them to 

 ascend vertical polished surfaces, they cannot be considered as wholly settling the 

 question as to the precise way in which these pulvilli, and those of insects generally, 

 act in effecting a similar mode of progression ; and my main reason for here giving 

 these slight hints is the hope of directing the attention of entomological and micro- 

 scopical observers to a field evidentl}-, as yet, so imperfectly explored. 



After writing the above, intended as the conclusion of this long note, I witnessed 

 to-day (July 11, 1842), a fact which I cannot forbear adding to it. Observing a 

 house-fly on the window, whose motions seemed very strange, I approached it, and 

 found that it was making violent contortions, as though every leg were affected 

 with St. Vitus's dance, in order to pull its pulvilli from the surface of the glass, to 

 ■which they adhered so strongly that though it could drag them a little way, or 

 sometimes by a violent effort get first one and then another detached, yet the 

 moment they were placed on the glass again, they adhered as if their under side 

 were smeared with bird-lime. Once it succeeded in drajj^ging off its two fore legs, 



