J918.] 133 



some groups of plants they manifest a strong partiality which contrasts 

 very forcibly with their utter indifference to, or perhaps one should say. 

 their entire avoidance of, others. 



Looking at plants as a potential food-supply, we must remember, 

 that, as the mouth-organs of the Heteroptera always consist of four fine 

 and sharp-pointed setae, lodged in a trough-like labium, and used as a 

 single piercing organ, the only food that can be taken is of a liquid 

 nature, and must be reached by the penetration of the cuticle of the 

 plant by the cibarial setae of the insect, so as to gain access to the 

 juices that lie beneath. These setae are xerj flexible, and could not, 

 even when combined, be used as a piercing organ, unless strengthened 

 and guided by the more sul^stantial labial trough, which does not itself, 

 however, enter the perforation that is made. It is, therefore, only at its 

 softer parts that the prey, whether animal or vegetable, can be success- 

 fully attacked. But as there can scarcely be any British plants that do 

 not present somewhere or other over their surface a cuticle delicate 

 enough to be pierced by the rostrum of even a weak bug, it would seem 

 that the avoidance of certain species of plants cannot be due to any 

 intractability in the material, or, in other words, to any mechanical 

 difficulties involved in getting at the enclosed juices, but must be 

 attributed to some distastefuhiess in the plants. 



Nor does the selection, or the degree of popularity of the plant 

 appear to be dependent upon the attractiveness of its appearance ; in 

 fact, very often the reverse is the case, for plants which are of insig- 

 nificant aspect, and possess no showy colours, are often very nuich sought 

 after, to the neglect of more conspicuous species, and in this category 

 come mosses, grasses, and the Umhelliferae. Tlie abundance or other- 

 wise of a plant no doubt has some intkience on the choice ; but even this 

 cannot alwa3's be the determining factor ; e. cj. there are few more a])un- 

 dant plants than the Dog's Mercury (^Mercnrialis perenn i s), ^\'i(\. yet not 

 a single bug is recorded from this plant. And, again, such common 

 weeds as Capsdla and Cardamine ])raiensis are entirely neglected. 



Few of the existing records made by Hemipterists sj)ecify the 

 particular part of the plant on which the bugs occur, whether stems, 

 leaves, flowers, or fruit, though a distinction is ciunmonly drawn between 

 the upper parts and the neighbourhood of the roots. But, in my own 

 experience, when the insect occurs on the upper |)ai-ts, it is almost alwavs 

 on or under the leaves, except in the case of the Umhelliferae^ when the 

 tlowers are preferred. One species of Lyr/aeidae, Ghilacis fypliae, appears 

 to be found exclusively in the heads of the Keed-Mace {Typlia). A few 

 species take up their abode on the trunks of trees, hiding, or perhaps 



