FAM. MEMBRACIDiE 39 



It is known, also, that certain species change their hosts during the life cycle, the nymphs 

 migrating from the host on which the eggs were laid to feed on another host and returning to the first 

 for oviposition. For example, Slictocephala inermis usually feeds on alfalfa but oviposits on pear and 

 apple ; Ceresa bubalus feeds on sweet clover but oviposits on elm ; Ceresa tattrina feeds on aster but ovipos- 

 its on pear and apple. 



As in the case of the life histories of the Membracida, much study needs to be made of the host 

 plants, particularly of the tropical and Old World species, before sufficient data are available for a 

 satisfactory knowledge of this subject. 



ENEMIES 



The Membracida seem to have but few natural enemies. Field notes covering a long period of 

 yearsshow surprisingly few cases of these insects actually having been observed captured or eaten by 

 other animals. 



Birds undoubtedly occasionally prey upon membracids, especially the soft bodied nymphs, but 

 the insects form a relatively small part of their diet. The stomach analyses of insectivorous birds show 

 only a meager percentage of Membracida. Wildermuth (igiS) reports that of thirty-one birds, repre- 

 senting eight different species, ten had from one to four adults oi Stictocephala festina in their crops; the 

 writer (1917) published an unimpressive list of birds representing nine species feeding on eight species 

 oi Membracida and McAtee (1918) believes that birds capture more membracids than has generally 

 been supposed. These records, however, do not indicate that membracids form an important 

 proportion of the diet of any bird. 



Toads have been known to capture membracids, particularly nymphs, and Asilids commonly 

 carry off both nymphs and adults. Spiders often catch membracids both in their webs and on the 

 twigs and the Mantis is not averse to an occasional specimen. On the whole, however, the damage 

 done to the membracid population by these enemies is not great. 



More important are the fatalities due to parasites which are found on both eggs and adults. 

 The egg parasites in most cases are Chalcidida but only a fcw have been determined, the only one ever 

 reared by the writer being Polynema striaticorue Gir. Observations on egg parasitism would indicate 

 that the parasite deposits its eggs in the newly laid eggs of the membracids and passes its larval and 

 pupal stages within the egg. On maturing, the adult hymenopteron emerges by breaking off the cap 

 of the egg-shell, which has meanwhile become discolored or blackened. Parasites on menibracid eggs 

 have been reporled by Jack (1886), Ashmead (1888), Murtfeldt (i8go), Hodgekiss (1910), and the writer 

 (igiSf, 1917) but only a few of these, including the one described by Ashmead Trichogramma ceresarum. 

 have ever been positively determined. 



Parasites in nymphs and adults are very common but have seldom been successfully reared. 

 The writer has found larvae, which were apparently hymenopterous, in the abdomens of many species 

 of Membracidte, but all attempts to bring the parasites to maturity have thus far failed. We beiieve 

 that more than one season is probably required to complete the life history of the parasites and that 

 our failures may have been due to the fact that sufficient time was not allowed for development. 

 Matausch (191 1) reported parasitism in Membracida which he believed was responsible for the destruction 

 of sex organs but he was equally imsuccessful in rearing a single specimen of any of the parasites 

 although he presents an excellent figure of the larvas. Apparently there is some phase in the life 



