12 



CHRYSOMELINjE. 



in the genus Chrysocloa, Hope (Oreina, Motsch.) ; in Ch. vittigera, 

 Suffr., Ch. cactdice, Schrank, and Ch. gloriosa, F., by Champion and 

 Chapman (Trans. Ent. Soc. London, 1901, pp. 1-17, pis. 1, 2); in 

 Ch. superba and Ch. speciosa by Perroud (Ann. Soc. Linn, de Lyon, 

 1855, pp. 402-8); and in Ch. speciosa, var. venusta, by Bleuze 

 (Petites Nouvelles Entomol., Oct. 1st, 1874, and Ent. Mo. Ma<r., 

 xi, 1874, p. 135). According to Perroud, Ch. superba only lays 

 one larva at a time, at intervals of about twelve hours. In 

 Phytodecta viminalis, L., C. B. Williams has observed (reference 

 given on p. 11) that the young are laid in a batch, the number in 

 one family varying from twenty-eight to forty. Amongst a batch 

 of thirty females under observation none (with one doubt ful excep- 

 tion) laid a second batch, as occurs, for example, in the Coccinel- 

 liu.e. In an account of the life-history of Ph. viminalis, Cornelius 

 in 1857 (Stett. Eur. Zeit., xviii, p. 165) has observed that the 

 beetles laid eggs which batched on the first day. He describes 

 the eggs as reddish in colour and cylindrical, slightly pointed 

 at the ends. It would appear, then, that the same species can, 

 under different conditions, be either viviparous or oviparous. 



Economic Importance. 



The Chrysomelik/E are very important from the agriculturist's 

 point of view. They are all plant-feeders, and therefore must be 

 looked upon as potential enemies. Under circumstauces favour- 

 able to itself a species can assert itself and become a terrible 

 pest — witness Leptinotarsa decemlineata, Say, the well-known 

 Colorado Beetle, which has only by great vigilance been prevented 

 from spreading in Europe as it has done in America. The fol- 

 lowing is a list of species of this group which are known to attack 

 cultivated plants : — 



Zygogramma exclamationis, F. America. Wild and cultivated 

 Sunflower. 



Leptinotarsa decemlineata, Say. America, Europe. Potato. 

 Ceralces ferrugineus, Gerst. West Africa. Manihot glaziovii. 

 Colaphellus sophice, Schall. Europe. Mustard. 

 Gastroidea polygoni, L. America, Europe. Polygonum, Sugar- 

 beet. 



Gastroidea viridula, Deg. England. Dock and Sorrel. 

 Gastroidea cyanea, Melsh., var. cassia, Bog. California. Grape- 

 vines. 



Phaedon armoracioz, L. Europe. Crucifers. 

 Phaedon assamensis, Jac. India, Assam. Mustard. 

 Phaedon cochlear ice, F. Europe. Mustard, Horse-radish. 

 Phaedon viridis, Melsh., var. ceruginosus, Suffr. America. 



Watercress. 

 Phaedon incertum, Baly. Japan. Turnip. 



Paraphaedon tumid 'idus, Germ. England. Potato (the ordinary 

 wild hosts of this insect are Umbellieerjs, Cheer ophyllum, 

 Heracleum , etc, ). 



