98 



KNOWLEDGE. 



[May, 1902. 



of the boilj' soinewbat interferes with the (k'ccptiveiiess of 

 the appearance. The legs are so extremely thin as to l)e 

 visible witli ilifficulty at a little distance, when the insect 

 is resting up(in the leaves of its foo(l-i)lant, though they 

 stand ont plainly enough when viewed against a back- 

 ground of white card, as would be the case in a collector's 

 cabinet. It is doubtful, therefore, whether the insect is 

 to any extent benefited by its superficial resemblance to 

 a carnivorous and dangemus animal such as a sjijiliT. 

 The enchanter's nightshade often grows under beech 

 trees, and the reddish yellow bud-scales of these, as they 

 fall from the tree, may often be seen lying on the leaves 

 of the plant, in which position they look much like the 

 body of Mi'ldtrnpin, but this again may be nothing more 

 than an accidental resemblance. There would seem to be 

 two advantages connected with length and slenderness of 

 legs. As already stated, they are practically invisible 

 except at close quarters, and they give, of course, a longer 

 stride, enabling the insect to traveree a fairly long distance 

 in a short time without proceeding at any great speed. 

 But, as Metatropis does not appear to wander much, 

 remaining all its life in close association with its food- 

 plant, this last property can hardly be of much service 

 to it. 



Another member of the same family is Metacanthus 

 pvndipes (Fig. 2), a much commoner insect, which can 

 usually be found in sandy places, wherever the rest-harrow, 

 with its pretty pink pea-like flowers, grows. It is a much 

 smaller insect than the preceding, and from the absence 

 of colour in its wings, looks a good deal like a gnat. 

 Anyone who wants to find this curious creature should 

 select a luxuriant patch of rest-harrow on sandy soil in 

 July, August or September. If the outlying branches be 

 lifted up, the probabilities are that Metacanthus will l)e 

 seen in numbers underneath, perhaps both the green 

 larvae and the greyish looking perfect insect being present 

 together. Under the microscope this is really a very 

 pretty insect; its black head and red neck contrast finely 

 with the yellow thorax with its two black patches in front, 

 and its black-tipped keels. The triangular hinder part of 

 the thorax, or scutellum, carries a cvirious curved spine, 

 the use of which can only be conjectured. In other 

 respects this insect is like a small edition of the pre- 

 ceding one. Like Alelatropis it is always found in close 

 association with its food-plant, upon the juices of which 

 it subsists. These two insects very well illustrate the 

 close connection that so often exists between the vegetable 

 and animal worlds ; they are natural parasites upou 

 their special food-plants, and their fortunes are entirely 

 dependent u])on that of the jjlants. 



Closely allied to these two, and with even narrower body 

 and finer legs, is Neides tipularius (Fig. 3). It is a 

 yellowish grey insect, about the size of Metatropis, with 

 the same clubbed legs and antenme, and the same minute 

 feet, but without the black spots on legs and antennae. 

 Unlike the other two, it does not seem to be attached to 

 any particular food-plant, and indeed is seldom found 

 otherwise than singly and promiscuously. It frequents 

 heathy and sandy places, and may sometimes be discovered 

 lurking under dead leaves, or at the roots of i)lants in such 

 situations, as well as on the plants themselves. Its sandy 

 colour, and its general slenderness of build, make it 

 difficult to detect when on the ground, provided it has the 

 wisdom to remain still. If it moves, its comparatively 

 large size at once betrays it. 



For our next example of stilt-walkers we must go to 

 (juite another family, in which we shall find considerable 

 difference in structure as well as in habits, though with 

 the same slenderness of build, or rather with the slender- 

 ness accentuated. The best example is Ploiaria niifnhtnida 



(Fig. 4), which, if we exclude the numerous spi-cies of 

 gnats and their allies in the order Diptera, is unquestion- 

 aldy the most delicate insect in our British fauna. All 

 the clubs have practically disappeared from both legs and 

 antenna;, and these have, in their slenderest parts, become 

 considerably finer than human hairs, as may easily be seen 

 by ]ilacing a hair beside them. Fine though they are, let 

 it lie remembered that they are tubes, carrying within 



Fig. 3. — Seides tipulari 



Fig. 4. — Ploiaria ragabunda. 



them the muscles required for locomotion. Both legs and 

 antennse are beautifully adorned throughout their length 

 with black rings placed at intervals, and are set throughout 

 with long hairs, which, of course, are much finer than the 

 legs to which they are attached, and are quite invisible to 

 the naked eye. Concurrently with the reduction in the 

 thickness of legs and antenna?, there has been a propor- 

 tionate lessening of the length of the foot, which is about 

 as short as it could well be. Only two pairs of legs 

 partake of this elongation ; the front pair are short, and 

 comparatively stout, and they are noteworthy for the 

 unusual length of their basal joints or coxee, which, instead 

 of being embedded as usual in the general armature of 

 the body, pi'oject considerably, and so give the legs greater 

 freedom of motion. These legs are used for predatory 

 purposes, for the insect, though of so delicate a structure, 

 is strictly carnivorous in habits, feeding upon the juices 

 of other insects, which it catches with these legs. The 

 sucking beak, or rostrum, as usual in this particular 

 family, is short and curved under the head, but not laid 

 close against the breast, as is the case in most other 

 Hemiptera. The upper wings are beautifully mottled with 

 dark grey, making an exquisite pattern like that of grey 

 marble. The hinder part of the thorax carries two long 

 spines, one behind the other, while a third appears at the 

 base of the abdomen. The eyes are very prominent, and 

 the insects have unquestionably good powers of vision, as 

 might be expected from their carnivorous instincts. 



These exquisite insects are to be found in all sorts of 

 localities. Often they occur on trees, especially oak and 

 fir, but perhaps ivy and holly are as attractive as anything 

 to them. Of course these trees are frequented not for 

 their own sakes, but on account of the other insects which 

 they harbour. On one occasion I found a large assem- 

 _blage of them on some oaken palings. Such palings are 

 well known to entomidogists as good hunting gi-ounds, 

 and Ploiaria had no doubt in this instance discovered the 

 same fact. Although they occur on such trees as above, 

 often in considerable numbers, it would be quite useless 

 to search the branches for them, as their grey colour and 

 extreme slenderness make them quite invisible in such 

 situations. If the branches be shaken or tapped over a 

 sheet or some other clear surface, the insects will easily 



