110 



TEXT-BOOK OF ENTOMOLOGY 



(1) with an unpaired median empodium ; (2) with two outer lateral 

 adhesive lobes ; (3) with two adhesive lobes below the claws ; the 

 latter is the chief type and forms either a climbing or a clasping 

 foot, The amount of movement possessed by the claws is limited, 

 and what there is, is effected by means of an elastic membrane and 



'xn 



FIG. 135. Honey-bee's foot in the act of climbing, showing the automatic action of the pulvillus, 

 x 3d : .-1, position of foot in climbing- on a slippery surface, or glass ; pr, pulvillus ; fh, tactile hairs ; 

 mi. iniguis ; t, last tarsal joint. , position of foot in climbing- rough surface. C, section of pul- 

 villus just touching flat surface; cr, curved rod. D, the same applied to the surface. After 

 Cheshire. 



the extensor plate (Fig. 110). The " extensor sole " which is 

 always present in insects with an unpaired median fixing or adhesive 

 organ (empodium) is to be regarded as a modification of the extensor 

 seta. The extensor plate is peculiar to an insect's foot. Ockler 

 states that the so-called " pressure plate " of Dahl is only a movably 

 articulated, skeletal, supporting plate for the median fixing lobule. 



Climbing. - - In certain respects the power of climbing supplies the 

 want of wings, and even exists often in house-flies among Avhich 

 there is shown a many-sided motion that is quite unheard of in other 

 groups of insects. 



The best climbers are obviously those insects which live on trees 

 and bushes, as, for example, longicorn beetles and grasshoppers. 

 These may be accurately called the monkeys of the insect kind, even 

 if their movements take place less gracefully, and indeed rather 

 stiffly and woodenly. We already know what are the proper climbing 

 organs; that is, the sharp easily movable claws on the foot. With 

 the help of these claws certain insects, May-beetles for example, 

 can hang upon one another like a chain; indeed, bees and ants in 

 this manner bind themselves together into living garlands and 

 bridges. There are still added to the chitinous hooks flaps and 

 balls of a sticky nature, by help of which likewise the insects glue 

 iht'inst'lves together. To facilitate the spanning of still thicker 

 1\vigs, the climbing foot of insects has a greater movability even 

 than when it only serves as a sole. (Graber.) 



The mode of swimming of insects. - - To study the swimming move- 

 ments of insects, let us examine a Dyticus. It will appear, as Graber 

 states, to be wonderfully adapted to its element. 



