INTKODUCTION. 25 



One of the most interesting uses o£ the anal secretion of 

 I'urculionid larva? is to be found in tlie genus Larhms. These 

 insects generally pass the larval stage in the heads of various 

 flowers, usually' of the thistle family, and most of them pupate 

 in tlie same position. But in Asia Minor, Persia and Northern 

 India there are certain species, including L. macuhtins, (xyl., and 

 L. syriacus, Gyl., the larvae of which leave the flower-heads when 

 full-grown and construct on the stem of the plant a nodular 

 cocoon, of the size of an olive, formed of a dirty white, chalky 

 substance secreted by the Malpigliian tubes. 'i'hese cocoons 

 form an article of commerce in the East, being largely used 

 both medicinally and as a food. The constituent materials have 

 been chemicallv studied by Berthelot (C. K. Acad. Sci. Paris, 

 slvi, 1858, pp. 1276-79) and have been found to contain about 

 66 per cent, of a sago-like subc^tance, known as trehalum, and 

 28 per cent, of a sugar allied to cane-sugar and called trelialose. 

 For medical purposes a decoction, is made from the cocoons 

 before the weevils have matured, and this is considered to be a 

 very effective remedy for bronchial catarrh. 



Another allied larva has also been utilised in medicine, namely, 

 Kliinocyllus antiodontahjicus, Gerbi, and, as its specific iiame 

 implies, it was sup])osecl in certain parts of Europe to afford a 

 remedy for tooth-ache. The bulky larvte of Bhynchojjhoras and 

 allied genera are eaten as delicacies by the natives in many parts 

 of the tropics; and in Australia A. M. Lea notes that the 

 larvjB of a species of Strongylon-hinus, which occur in large 

 galls on Eucalyptus trees, are "eaten by tiie blacks, and by 

 not a few white men" (Proc Linn. Soc. JM.S.AV^ xxii, 1897, 

 P- 619). . . 



The gall-making habit is not an uncommon one m 1 he family, 

 being found in such genera as Sihinia, Apion, ]S(moi>liyes, Gym- 

 netron, Miarus, CeiitJwrrhyncJius, Bans, etc., and the galls may 

 be made on either the stems or the roots of the food-plants. 

 Two European species of Balaninus are stated to make use of 

 the galls of certain Hymenoptera for their own larva\ 



In 1902 the Eussian entomologist, A. A. Silantjev, made the 

 interesting discovery of the existence of parthenogenesis in the 

 genus Otiorrhynclius. He was struck by the fact that while pairs 

 of the less common 0. asphaltinus, Germ., were frequently 

 observed, this was never the case with 0. turca, Boh., although 

 this is an abundant vineyard pest of which he had seen hundreds 

 of thousands. One thousand specimens taken at random proved 

 to be all females, and subsequently specimens were reared 

 parthenogenetically (Zool. Anzeiger, xxix, 1906, p. 583). _ Later, 

 I. V. Vassiliev showed the same to be tlie case with 0. Uyustici, 

 L. (Zool. Anz. xxxiv, 1909, p. 29) ; while in Italy in 1913 

 Grandi demonstrated the existence of the same phenomenon in 

 0. cribncollis, Gyl., of which he states that no male specimen is 

 yet known (Bull". Lab. Zool. Portici, vii, 19]:?, p. 17). 



