" MANKA " OB LERP INSECT OF SOUTH AUSTRALIA. Ill 



Mueller; but uDfortunately they arrived in a state unfit for 

 identification. 



Eucalyptus oleosa is a species with an underground rootstock, 

 from whicli numerous small stems, generally crooked and semi- 

 sarmentose, spring. When these are destroyed by fire &c., a host 

 of fresh ones spring up from the caudex ; and on these, not the 

 branches of normal and mature stems, the Lerp insect produces 

 the manna. It consists of circular or broadly oval disks about 

 y^ inch diameter, convex above and concave belov/, formed of 

 small irregular globules of solid melitose agglutinated, and there- 

 fore exhibiting a rough exterior sui^face. They are crowded 

 around the branchlets, frequently for a length of 6 to 10 inches, 

 and appear first as small specks in December or January. 

 Under each is found a small larva, its short proboscis buried in 

 the bark, and thus fixed to the spot for the period. The imago 

 is very nimble, only about two thirds of a line in length, inclu- 

 ding its long transparent wings. Copulation takes place almost 

 immediately after emergence. 



There is found occasionally a kind of melitose on the leaves of 

 Eucalyptus gracilis (solitarily), but more frequently on those of 

 low bushes of E. leucoxylum in varying numbers, and in the form 

 of extremely regular, thin scales formed of radiating curved rods 

 united longitudinally, and resembling the half of a minute bivalve 

 shell. These are much larger than the one described ; but the 

 species has not been sufficiently observed to do more than to 

 mention its existence. 



Addendum. — Since the preceding paper was read and in type the author has 

 forwarded a letter, of which the following is a summary of the contents : — 



Eeferring to my communication on the Lerp insect, Baron Ton Mueller has 

 lately kindly sent me the Proc. Eoy. Soc. Van Diemen's Land, vol. i. (1851), 

 which contains (p. 235) a paper on the subject by Mr. Thos. Dobson, and 

 another {I. c. p. 241) on the Chemical Constitution of the Manna by Dr. Thos. 

 Anderson. I believe, however, that neither of the Lerp insects therein de- 

 scribed are identical with that observed by myself, though one of them may be 

 closely related to that produL'ing the larger symmetrical shields on leaves as 

 noted by me. The pupa-case figured by Dobson appears quire correct, as I 

 have seen somewhat similar perfect inset^ts emerge from cases not unlike his. 

 I myself have examined with a pocket-lens branclilets covered by insects in all 

 stages ; but later in the season one finds nothing but empty cases. I also am 

 of opinion that the solid and the fluid melitose are of quite distinct origin, the 

 latter being due to the larva previously juentioned ; but the former is of more 

 doubtful origin. It certainly is not produced by the Cicada viminalis, nor is it 

 confined to Eucalyptus viminalis, though most abimdant on that tree. It does 

 not occur every year, nor always where the tree abounds. 



[Reference may here be given to a paper on the Lerp's constructions by 

 Mr. W. H. Wooster, Journ. Micros. Soc. Victoria, vol. i. p. 91, pi. vii. (1882).] 



9* 



