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ORDER IX (THYSANOPTERA). 
Family Thripidse (Thrips). 
See " Studies on Australian Thysanoptera : the genus Idolothrips Haliday," 
by W. W. Froggatt (Proc. Linn. Soc. N.S.W., xxix, 54, 1904). He figures and describes 
some large Australian thrips. These insects are to be found in all stages of growth by 
beating or shaking the dead foliage of Eucalyptus bushes, where the trees have been 
cut down, and the leaves have remained attached to the twigs, forming a close shelter 
for them. See also Froggatt, p. 393. 
Arachnideae (Mites). 
In addition to Insects, we have the Arachnidse, which include spiders, mites, 
ticks, and scorpions. Here are some notes on mites, because they often exhibit their 
destructive behaviour on the leaves of Eucalypts. But their effect on our forest 
vegetation has been but little recorded in Australia. 
Mr. E. Cheel showed (Proc. Linn. Soc. N.S.W., xl, 117) the effects of a Mite 
(Phytopus or Tetranychus probably), on the leaves of a number of plants, e.g.,E. saligna 
from Moona Plains, Walcha (collected by the late A. K. Crawford), and E. sp. Jellore 
Creek (collected by himself). The pathological effect is to produce a beautiful crimson 
granular appearance on the underside of the leaf. 
The phenomenon is known as Erinosis, and besides those mentioned I have 
seen beautiful specimens in E. stricta, Blackheath, Blue Mountains, New South Wales, 
E. Muetteriana, Dumaresq, Armidale, New South Wales, and E. obliqua, Bunyip Creek, 
Victoria. 
Damage on leaves of E. saligna, Killara, Sydney (W. F. Blakely), is stated by 
Mr. Froggatt to have been apparently caused by mites. 
In discussing galls, Goebel (" Organography of Plants," i, 1900, footnote, p. 196), 
says, " Moreover: there are cell-forms which are non-existent if the development is 
undisturbed, for instance, the hair-formations of ' Erineum galls'; and these hair- 
formations, which are induced by the attack of mites, are serviceable to the parasite, 
and diverge altogether in structure from the normal hairs of the plants on which they 
occur." 
Following is a note from Kerner and Oliver's " Natural History of Plants," ii, 
529. The various kinds of galls have been discussed. 
" The majority of felt-galls are produced by gall-mites. They form cottony 
or felted growths on limited and sharply defined areas of green leaves and stems, the 
surface of which is otherwise smooth, or possesses but few hairs. 
The colour of the felted hairs varies according to the plant, . . . the 
itimulus being afforded by a minute gall-mite (Phytopus)." 
It should be mentioned that formerly thess velvety and felted coverings were 
regarded as Fungi, and were described as distinct genera under the names Erineum and 
Pltyllerium (e.g., the gall known as Erineum qucrcinum on the leaves of Qucrcus (erris). 
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