THE CANADIAN ENTOMOLOGIST. 89 



the aesthetic value of dual symmetry is greater in the horizontal 

 than in the vertical. 



In addition, other forms of symmetry can be found in insects, 

 due to the arrangement of wings, venation and colour patterns. 

 In fact, aesthetic appreciation of insects is due to many factors, 

 among which are symmetry, proportion, intensity and arrangement 

 of colours and experience and familiarity with the insects in ques- 

 tion. 



In the Lepidoptera horizontal dual symmetry is quite common, 

 but in addition the lateral halves of many members possess radiating 

 symmetry by reason of radiating wings and veins. The repetition 

 of certain designs or colour spots arranged in curves or lines can 

 be called running symmetry, and at times rotating symmetry is 

 found, as, for example, the circular spots of Aiitomeris io. In a 

 few instances lepidopterous insects are exploited by movements of 

 the eyes above and below the horizontal line formed by the pos- 

 terior edges of the first pair of wings. In many individual butter- 

 flies and moths nea-rly all of the above forms of symmetry can be 

 found, and when such a multiplicity occurs the insect assumes a 

 complexity, which may or may not, according to one's training, 

 be viewed with aesthetic pleasure. 



Members of the Diptera possess in the main horizontal dual 

 symmetry, and at times radiating symmetry of the wing veins. 

 Many of the Hymenoptera present radiating symmetry due to 

 their narrow wings radiating from the thorax, although all four 

 elements are not equal. In mounted specimens the arrangement 

 of the legs also tends to induce divergent radiating exploitation. 



In the Orthoptera the expanded hind wings of the Acridiidai 

 contain intense radiating elements, and many of the Odonata 

 possess a four-fold radiating symmetry due to the radiation of 

 their narrow equal wings. In the majority of the Orthoptera and 

 Hemiptera dual symmetry in the horizontal is most apparent. 

 While some members are exploited in different ways, very few of 

 such movements induce what is known as aesthetic pleasure. 



Many of the Coleoptera, in addition to possessing horizontal 

 dual symmetry, which is not very apparent at times, also exhibit 

 proportion or a pleasing inequality of parts shown in the proportion 

 between the length and width of the insect. To many persons 



