250 



AUSTRALIAN PSYLLID.E. 



By Walter W. Froggatt, F.L.S. 



(Plates xi.-xiv.) 



Introduction. 



The insects of this family of the Homoptera, like those of 

 several other groups of the order, are very interesting because of 

 the remarkable larval and pupal transformations they exhibit in 

 the course of the metamorphosis, as well as for the curious pro- 

 tective coverings — lerps or scales— which many of the tiny larvae 

 commence to fabricate as soon as they emerge from the egg. The 

 lerp or scale is added to as the insect increases in size up to that 

 of the full-grown pupa; then crawling from beneath it, it casts 

 the final pupal shell, and emerges as the perfect insect. 



The best known Australian species are those that form the leaf 

 manna upon the foliage of Eucalypts. As far back as 1849 

 Anderson (1) described the chemical composition of some "manna"' 

 (lerp) that had been obtained in the Mallee-gum scrubs in the 

 north-western part of Victoria. This paper was reprinted by 

 Dobson (2), who added a description of an insect which forms 

 similar sugar-like lerp on the foliage of Eucalypts in Tasmania, 

 under the name of Psylla eucalypti. He gave a careful account 

 of the way in which the larva? construct the scales; and he figured 

 two other species besides the one he named. 



Another interesting paper dealing with the structure of the 

 lerp-scales was written by Wooster (3) who watched the larvse of 

 the same or an allied species lifting the sides of the scale while 

 they raised the walls to form an addition to it from below. 



Tepper (4) has also given a general account of the so-called 

 "manna" upon the leaves of Eucalyptus gracilis and E. leucoxylon 

 in South Australia. 



