378 TRANSFORMATIONS OF INSECTS. 



France, and their wings are transparent and without any colour, 

 but this is not the case with the species of India and southern 

 Africa, for they have their wings magnificently tinted. The song 

 of some of the Brazilian species is said to be heard for the distance 

 of a mile ; and one American species, which is called the Seventeen 

 Years' Locust, does a great deal of mischief. Ever since the year 

 17 1 5, when its visit was first recorded at Philadelphia, no causes 

 have affected the regularity of its return at intervals of seventeen 

 years, even to the very month. 



It is very common to notice on the leaves of willows and sal- 

 lows by the river side little spots which look like saliva ; if this 

 matter is removed a larva or a nymph may be detected. It is 

 called in England the Cuckoo Spit, or Frog Hopper, and is 

 commonly found frequenting garden plants. The insect is called 

 AphropJiora spuniaria. The larva and pupa invest themselves 

 with this frothy secretion, in which they lie hid until they com- 

 plete their transformations. The frothy matter is vulgarly sup- 

 posed to be really the spittle of the cuckoo. The larvae are 

 quite destitute of any wings, and they are only rudimentary in 

 the nymphs. The adults have legs fitted for leaping, and they 

 suck the juices of plants with the aid of their suckers. 



Some of the AphidcB or the Plant Lice have wings which 

 are always more transparent than those of the little CicadcllcB 

 just mentioned ; they have also long antennas, which are com- 

 posed of seven pieces. They are provided with two small tube- 

 like projections, which stick up from the end of the abdomen, 

 and which communicate with each other, and with a gland that 

 secretes the sugary liquor of which the ants are so fond, and 

 which is said by some naturalists to nourish the newly-born 

 Aphides. There is no doubt about the ants milking the plant 

 lice by tapping them on the end of the tubes, but it is a matter 

 of doubt whether the young ApJiidce have the sense or the power 

 to avail themselves of what certainly might be very nourishing 

 to them. The males of the plant lice have large wings, but 

 almost all the females are deficient in these organs of flight. 



It was formerly a great puzzle to understand or to 

 account for the rapid increase of plant lice, and the question 

 has been carefully entertained by some of the most distinguished 



