130 
DoBsoN^ 071 Laap, or Lerp. 
of the Aphis, a genus very closely allied to Psylla. The 
larva of Psylla Betulm, according to Mr. Curtis^ and of other 
species of the same genus, is covered with a white cottony 
secretion, and their excrement (as it is termed) is said to form 
threads or masses of a gummy sucreous nature. But an obser- 
vation most to the point as regards the present subject occurs 
in the ^ Memoires pour Thistoire des Insectes ' of the illus- 
trious Reaumur (tom. iii, p. 357, pi. 29). In his description 
of Psylla Buoci, he says, '^'^11 parait porter au derriere un 
morceau de vermicelli, dont la figure a ete mal moulee, car 
la couleur comme la figure de cette matiere ressemble assez 
a celle de la pate filee appellee vermicelli ^ He notices further 
that ^'^il sort de Tanus,^^ and that it dissolves on the tongue, 
having a taste " un peu sucre et qui est agreable ; c^est un 
espece de manne qui n'a pas les desagremens de la manne 
ordinaire.^' He observes also, that there would be no difii- 
culty, in many places, in collecting this sort of sugar in con- 
siderable quantity.^ 
In conclusion, it may be remarked, that the " Lerp^^ would 
appear to be a substance well calculated to form a substitute 
for sugar or malt in distillation. It would seem to occur in 
sufficient quantity to render it worth collecting for such a 
purpose. 
* Appended to this account of P. Puixi is a figure of the larva, in the 
act- of manufacturing the vermicelli, which so closely resembles the central 
larva in fig. 2 that the latter might almost be deemed a copy of it. 
