Art. XIV.—Note on Blights.
[Read before the Nelson Philosophical Society, 4th March, 1890.]
I. Dactylopius calceolariæ.
The chief point of interest about this was its extreme destructiveness and rapidity of multiplication, equalling that of the Aphides. In the course of six weeks from the time when it was first observed it completely killed a large dolichos covering one side of a house. Syringing with kerosene and soft-soap had apparently no effect.
II. Lecanium hispidum.
This blight infests orange- and lemon-trees, secretes honey-dew, and consequently renders the tree unsightly from the growth of black fungus. I observed a few specimens last summer (1888-89); during the winter they were almost stationary, but about last October they increased enormously, and in January there was not a leaf or bit of stem of one lemon-tree but what was infested with them. One evening last month I observed a small larva eating the crown of one of these Lecania, and I am now happy to say that I have since discovered adult lady-birds and numerous larvæ, all of which may be observed preying on the Lecania. I have submitted the lady-birds and their larvæ to Mr. G. V. Hudson, of Wellington, who informs me that it is a species of Rhyzobius; belonging to the lady-bird family, but not a Coccinella. He kindly furnished me with magnified drawings of the larva and perfect insect, which I append.
[Note in January, 1891—During the winter, both blight and lady-birds completely disappeared, and the tree now looks as clean and healthy as I could wish it. It is interesting to think where the lady-birds could have come from. They came, did their work, and then disappeared. Mr. G.V. Hudson is corresponding with English entomologists in order to exactly identify the species.]
Explanation Of Plate VIIIA.
Fig. 1. Rhyzobius.
Fig. 2. Larva of same.