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BY CLAUDE FULLER.
Many san ples of fruit taken from the large consignments of oranges and lemons recently imported from Sicily and Southern Europe, have upon examination proved to be suffering from insect attack. Thus again is the necessity for some measure of legislation emphasized, whereby this introduction from outside places of insect and other fruit pests can in some way be prevented or the danger thereof minimised.
The results which follow the scattering broadcast throughout the Colony of this blighted fruit are very much a matter of chance; yet a combination of circumstances is not altogether unimaginable whereby the insects might be transferred from markets or stores to neighbouring orange orchards. The following remark applies very well here:-“ Considerable quantities of this (diseased fruit) find their way into the shops of small country towns along the lines of railway. Much of it soon becomes too bad to use, and is then thrown out and the infected cases stacked in back-yards, in some instances but a very short distance from orchards. The codling moth appeared in Canterbury two seasons ago, and was unmistakably traced to a large stack of empty cases the fruit of which had been sold.'*
Elaborate quarantine regulations have been made and are in force to protect, apart from the well-being of inan himself, that portion of the community which is interested in the raising of sheep, cattle, horses, &c. Why then should the interests of fruit-grower and farmer, surely of no less significance than those of the stock-raiser, be, with the one exception of the vinegrower, entirely overlooked ?
The results which have followed the introduction of the codling moth are too well known and appreciated to need more than mentioning here, and yel this is only a single instance of the many others which have been and are still being introduced daily into the country.
One might be easily excused for asking -- are there any more pests which can be brought into our midst?—so many indeed are the noxious insects from which all branches of agriculture at present suffer. It is almost necdless to reply that, despite the number and variety we already have, there are many more, with natures equally reprehensible, likely, in fact certain, to be brought in upon imported fruits and plants.
In replying to the oft-repeated question as to wbether, in view of the fact that we have already certain insect pests, such as the codling moth, “Is it worth while legislatir.g to prevent further importation ? ”, Mr. Kirk, in the
* T. W. Kirk, Ann. Rept. N.Z. Dept. Agriculture, 1895.
report quoted above, asks “ Why do raisers of poultry and stock continually introduce fresh strains ?” Why! Simply because the new blood helps to keep up the stamina of the breed already here. The same thing applies in a sense to insects. What is the use of taking remedial and preventive measures if the forces of the enemy are being continually augmented ?
An orange, one of a large shipment from Sicily, was, a few weeks ago, referred to the Entomological Branch of this Department by W. H. Eldred, Esq., Consul for Chili.
A casual examination of the fruit showed a number of scale insects of the genus Mytilaspis, a group only too well represented in New South Wales by the mussel or oyster-shell scale of the apple (Mytilaspis pomorum, Bouché). The insects were clustered in a thick group upon the rind about the base of the stalk. Judging from its general appearance the insect was at first thought to be new; however, after a careful examination of the microscopic characters, there can be no doubt that it is the mussel scale of the orange, Mytilaspis citricolor, Pack., or a variety of it.
THE ORANGE MUSSEL SCALE (Mytilaspis citricolor, Pack.)
This insect has been previously reported as occurring upon citrus plants in this Colony by Mr. W. M. Maskell of New Zealand, and also by Mr. A. H. Benson of this Department. Mr. Maskell also records its occurrence in Queensland, Victoria, and South Australia.
It cannot as yet be regarded as a serious orange pest here, and excepting the above identifications, the name has often been applied to another and distinct insect, Chionaspis citri, which does much damage to mandarin trees, and goes by the popular name of "white louse."
The orange in question has now been under observation for several weeks, and during the early part of the time large numbers of young insects, or larvæ, have come from beneath the mother scales and established themselves upon the fruit. The late batching of the eggs is no doubt due to the artificial winter of the cold storage in which they have been carried.
Mytilaspis citricolor, a variety? The shields from which this group of the Coccididre derives its name of scale-insects are in the case of this female between it to 744 of an inch long, while the male scales are smaller, about in. The female scale is convex, curved, and mussel-shaped, of a whitish or grey colour. The colour is due to the presence of what might be described as a "bloom" upon the scales, which consists of the curled ends of inany cottony filaments, secreted by the insect in the formation of its covering. When the scale is removed from the fruit the insect is found completely enclosed between two shields; the upper or dorsal scale and the lower or ventral scale. The ventral scale comes directly in contact with the rind of the fruit, and is very strongly attached to the dorsal scale ; some difficulty being experienced in getting out the insect without damaging it. The female when removed is deeply segmented, and of a golden-yellow colour.
The differences between these Sicilian insects and Professor Comstock's description* are chiefly external. Professor Comstock describes M.citricolor as brown, with a white fringe; the ventral scale well developed, wbite, consisting of a single piece which is slightly attached at its sides to the lower edge of the scale, and is more or less incomplete posteriorly. In our specimens when fresh no other colour can be ascribed to them but white, although when rubbed they appear ashy grey, and sometimes brown; neither do they possess the white fringe mentioned. The study of the characters of the last segmont leaves no doubt about the insect's identity with M. citricolor, the only difference being that in Comstock's description the spines are spoken of as long, and the spinnerets, anterior group about 6, anterior laterals of about 18, and the posterior laterals about 9, whilst in the Sicilian specimens the spines are quite indistinct and short, spinnerets very variable, anterior group 5 or 6, anterior laterals 10-13, posterior laterals 7-9.
* Ent. Rept. U.S. Dept. Agric., 1880, p. 328.
Explanation of Plate. -1. Orange showing insects. 2. Group of scales magnified. 3. Female scale, dorsal view (magnified). 4. Female scale, ventral view (magnified). 5. Male scale (magnified). 6. Female coccus (magnified). 7 Anal segment of female (greatly magnified).