FROG-HOPPERS 253 



number from fifty to eighty in a swarm, and change to pupae after five or eight 

 days' feeding, developing into flies eighteen to twenty days later. 



The frog-hoppers, which form a group of the Rhynchota, infest the 



'Fro£T-Hot)D6rs ox %/ 



shoots and twigs of various plants. The well-known white froth so 

 often seen in meadows is emitted by the " nymphs " of the common frog-hopper 

 or cuckoo-spit (Aphrophora spumaria), which live in it, and are thereby protected 

 against their enemies, especially birds, until full-grown. From these nymphs develop 

 yellowish grey insects, a quarter of an inch long, whose wing-covers are generally 

 crossed with two crooked whitish bands. The females deposit their eggs in autumn 

 in the bark of trees, especially willows, and the grass-green larvas creep out in April 

 to fasten on meadow-sweet and other plants. Ever since the time when it was 

 seriously regarded as an emanation from the stars, or as the saliva of the bird from 

 which it takes its name, there have been constant discussions as to the origin of the 

 froth enveloping these nymphs, which, together, of course, with the full-grown 

 insects, are members of the family Cercopidce. 



Naturalists have tried to solve the problem, but, according to Mr. Braxton Guil- 

 beau, of Cornell University, in an article contributed to the American Naturalist, 

 none of them has been successful. To test the matter thoroughly, this gentleman 

 inaugurated a very careful series of experiments and observations, in which the first 

 process was to cleanse specimens of the nymphs from all traces of the investing froth 

 by means of a camel-hair pencil, and then watch their actions when placed on twigs. 

 When thus situated, the first action of the insect is to dig its beak firmly into the 

 bark, soon after which its body will be observed to swell, while a little drop of clear 

 liquid will be observed to issue from the vent. After a quantity of this fluid has 

 accumulated about its body, the last, and sometimes also the second, pair of legs 

 are moved to the region of the seventh and eighth abdominal segments, and rubbed 

 against the body, as if in the action of mixing substances. After the fluid had 

 been thus mixed so as to completely cover the body, the creature moved the tip of 

 its abdomen out of the liquid, opening up the pair of lateral appendages of the 

 ninth segment, which were again immediately closed. Then, with a downward 

 movement, these parts were reimmersed in the liquid, when the appendages were 

 opened and released a bubble of air in the liquid ; and by the repetition of this 

 process the insect soon became involved in a mass of the characteristic froth. 

 Bubbles of different sizes can be made by regulating the size of the air-grasping 

 pocket of the appendages. To complete the production of the envelope of froth, a 

 mucilaginous substance is added from certain abdominal organs known as the 

 glands of Batelli, this rendering the liquid viscous, and therefore better adapted 

 for retaining the air-bubbles. The problem thus appears at last to have been 

 completely and satisfactorily solved. 

 Fan-Winged A brief notice must suffice for the fan-winged insects (Stylopidce), 



insects. whose females are wingless and legless, while in the males the front 

 wings are stump-shaped and rolled up at the tips, and the hind-wings large and 

 capable of being opened and closed like fans. These curious insects undergo a 

 complete metamorphosis, and their larvae are parasitic in the abdomens of 

 Hymenoptera, out of which they creep between two of the abdominal segments 



