3 78 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 
1715, 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 
Aphrophora spumaria. 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 larve 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 Aphide or the Plant Lice have wings which 
are always more transparent than those of the little Czcadelle 
just mentioned; they have also long antennz, 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 
Aphide. 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 Apszd@e 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 
