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Frog-hoppers or Spittle Insects

(Family Cercopidae.)

This is a rather large family comprising mostly rather small insects, many of which are known as "frog-hoppers" or "spittle insects." The antennae are placed between the eyes, there are only two ocelli and the thorax is not strangely modified as with the Membracidae. Few insects excite more interest among moderately observant people than the true spittle insects which belong to the subfamily Aphrophorinae. They are small, rather slender, brown, clay-yellow or grayish species, and after hatching from the egg live in little masses of froth resembling spittle on the stems of plants and trees, frequently on grasses and weeds. In some parts of the south, according to Uhler, the negroes think that horse-flies are developed from these froth specks. When abundant they may do considerable damage to pasture-lands. Philaenus spumarius and P. lineatus are said by Fernald to be common on grass in Massachusetts. The former is abundant in gardens in England and was probably introduced from England into this country.

The eggs are laid in the stems of plants in the autumn and hatch in the spring. It was formerly thought that the spittle that soon surrounds the young insect was excreted from the anus, but Professor E. S. Morse has recently shown that only a clear liquid containing no bubbles is thus exuded and that the air-bubbles are brought in by a constant thrashing about of the anal end of the body, bringing in air which is retained as bubbles by the viscid quality of the liquid. There are anal appendages which are probably branchial in function, according to Morse.

It is supposed that the purpose of the frothy mass is to protect the soft-bodied immature insects from their natural enemies--in other words that it is a disguise. But it renders them very conspicuous and once their true nature is ascertained they are all the more easily found by their enemies and as a matter of fact they are sought for by certain wasps which drag them out from their froth and carry them off to provision their nests.

No good thorough life history of an American species has been published and here is an interesting and novel field for some observer.