460 



Marvels of Insect Life. 



The principal methods ad()})ted in the warfare ai^ainst the pest is the burninjj: 

 of the diseased plants, and the treatment of the soil whence they have come with 

 bisulphide of carbon and gas-tar. 



Another member of the genus ^ is found upon the oak. The female may be fo'.uid 

 on a discoloured patch of the oak-leaf where she has fed. Around her will be 

 found two or three circles of eggs, which will hatch in a few hours and set up 

 a cycle of forms which in about twenty-one generations results in the production 

 of sexually mature Insects. This oak-leaf aphis, like the multitude of other oak- 

 feeding Insects, appears to have no appreciable effect upon the tree, and is, therefore, 

 totally unlike in character to its congener of the vine. One of our photographs 

 shows a cluster of seventy -six eggs from which the female had dej^arted when they 

 were discovered, but from the seven eggs standing out from the outer circle it 

 appears that she has only moved a short distance, and is engaged in depositing 

 a second batch which already numbers seventy-one. The perfect sexual individuals 

 of this species are produced in autumn, and possess no sucking rostrum, so can 

 partake of no nourishment. The female lays only one big egg, which remains 



in a crevice of the bark 

 until spring, when it 

 produces a winged form 

 which lavs eggs on the 

 under side of the oak- 

 leaf. The produce of 

 all these eggs are wing- 

 less, and each of them 

 lays eggs in concentric 

 circles, as shown in our 

 photograph. The 

 young hatched from 

 these eggs are at first 

 rather active, and move 

 away from the egg-circle in quest of a feeding ground. They are dotted with small 

 orange spots. On some young oaks every leaf is swarming with these Insects. 



Musical Insects. 



Of a few Insect musicians it may be said that their power of producing 

 sounds has been notorious from the beginning of time. Some have regarded 

 these sounds as music, others as a wearying noise, and in all probability they will 

 continue to be thus div'ersely regarded, according to the temperament or the 

 condition of health of the hearer. The poets — and others — ha\'e made mistakes 

 about this music. Some have thought the Insects had real vocal apparatus, 

 others that the sounds were })roduced solely by rapid wing-vibration. But, as 

 one would expect to find among creatures of such \-aried organization, a similar 

 end is reached bv different means. Some have a real vocal apj^aratus, though 

 not connected with the mouth ; but in most cases it is more akin to the action 

 of lyre and |>l('ctriun. Tin- list ol Insect musicians is far too long to be desalt 



' I 'li\il(i\(.Ta imnctala . 



Photo 6yl 



[£. Step, F.L.S 



The Cicada. 



The most celebrated of the Insect musicians, whose powers were made much of by the ancient 

 Greeks. The apparatus for the production of sound differs altogether from those of all other 

 Insect musicians, as will be shown in further illustrations. It is shown with the wings 

 expanded for flight. 



