William Miles Maskell

“ An ordinary lens will generally show, springing from the point of the conical rostrum, three or four longish, very fine, curling bristles. These bristles are, in fact, hollow tubes, and the insect, inserting them into the leaf or bark of the plant, sucks through them its food. It is thus plain that, with often great numbers of scale-insects sucking at it—pumping, as it were, its life-blood through their rostra—a plant must of necessity suffer greatly.
Birds do not, as a rule, seem to care much about eating the Coccididæ, whose work is thus little interfered with by them. ”

“ But in no case does it appear that our Coccids [E] form honeydew to the same extent as the Aphides, which are stated to produce sometimes quantities that may be gathered from the leaves or the soil by the pound weight. It is not so much the amount exuding from each insect as the great number of insects on a plant which renders the Coccid honeydew obnoxious: each individual may excrete only a little, but when, as usually happens, there are many hundreds of individuals together, the result, for the reasons given below, becomes important to the tree. ”

“ To institute a comparison, it would be manifestly absurd to include such countries as England, or Germany, or, on the other hand, India, or Central America, or North Australia—Firstly, because in the greater part, or at least in the northern parts, of Europe the winters are much more severe than in New Zealand, and almost certainly the great cold is injurious to such insects as Coccids. Secondly, because in tropical countries it seems that the too great heat is equally obnoxious to them; and, with the exception of a few species, tropical Coccids are comparatively harmless. ”

“ In New Zealand, on account of the greater prevalence of Coccididæ, the insects will most probably be Coccids; but by no means necessarily so, for many Aphididæ, « 18 » Psyllidæ, and Aleurodidæ produce the same effects. This is by no means as well understood as it should be, either by gardeners themselves or by those who write on trees and planting. The fungus growth is usually imagined to be in itself a disease of the plant, and efforts are made for its treatment without regard to its real origin, the insects on the leaves or bark. ”

“ The opinion that Coccids are not likely to do much harm in the open air is therefore scarcely tenable, and it will be of use to inquire what remedies can be provided against them.
There is a point, however, to be noted at the outset, and it is, that in reality there is not, as far as is yet known, any certain remedy against scale-insects. Not that ingenuity and experiment have not succeeded in inventing plans and substances quite efficient in killing the insects when applied to them. It is easy enough to kill an insect when you can get at it, in most cases ”

“ In the Diaspidinæ the puparium is formed partly of fibrous secretion and partly of discarded skin; only, as the full-grown male emerges from it as a fly, and does not remain on the plant, there can be only one such skin—that of the larva; consequently it is easy to distinguish the male puparia from the shields of the adult females by the presence of only one discarded pellicle instead of two. In the Lecanidinæ and the Coccidinæ the male puparia are distinguishable usually by a narrower and more cylindrical form than those of the females, where these latter are covered ”

“ A few large conical spines (spinnerets) are scattered over the body, and a row of smaller ones, like hairs with tubercular bases, runs transversely on each segment; also some circular spinnerets. At the edge of the body, all round, is a row of the large conical spines, which are set in groups of three on the posterior segments, of four or five on the median segments, and almost continuous on the head. When the insect is alive these spines are often agglutinated with cottony secretion so as to give the appearance of a short fringe. The four spiracles are somewhat large and circular. ”

“ A work professedly dealing with facts should be as free as possible from controversial discussion. Whatever, therefore, may be the grounds of the opinion just stated, or the reasons for rejecting it, it will be sufficient here to say that there seems to be nothing to lead to the belief that New Zealand is likely to be different from other countries in this respect. ”

“ In the Lecanidinæ and in the Coccidinæ the skin of the larva is thrown away altogether, and the female in her second stage takes up a new position, in which she may be either naked or covered with a thin coat of secretion, active or stationary, retaining her legs in most cases, or losing them in some instances. In all the groups there is almost always some approach to the form of the full-grown insect noticeable in this second stage. ”

“ The object of the milk is not only to lessen the injurious qualities of the kerosene, but also to induce it to mix more freely with the water; but it is the oil alone which destroys the insects and their eggs. ”

“ In England they are less troublesome in the open air, though in greenhouses and hothouses they abound; but, in places under glass, every gardener ought to be able to get rid of them without difficulty. For its extent New Zealand seems to furnish a larger number than any other country. The humidity of its climate and the absence of anything like severe winters in most parts of it are quite congenial to Coccids; and there is scarcely a tree in its forests or in its gardens, whether native or introduced, which is not subject to their attacks. ”

“ Another mode by which the too rapid increase of Coccids is checked is by the attacks of vegetable parasites—fungoid growths which permeate the whole body of the insect, and soon kill it. As far as experience in New Zealand extends as yet the genera Ctenochiton, Lecanium, and probably Eriochiton are the only ones so attacked. ”

“ The experience of American fruit-growers is certainly not to be despised, and the fact that both in California and Florida the people strain every nerve to get rid of the insect pests on open-air trees would seem to be distinctly against the notion that these little enemies can be neglected with impunity. ”

“ Of all the family, Cælostoma zælandicum, in its second stage, seems to produce the greatest amount of material, its large, hard, waxy tests being very thick and solid, and often clustered in hundreds on a root or a twig of Muhlenbeckia; but, supposing this substance (of which the true chemical nature [D] is not yet known) to be fit for some purpose, there does not seem to be any means of cultivating the insect to profit. Dactylopius alpinus produces in alcohol a rich red tint, and this not by way of excretion, but from the colouring matters of its tissues, as in the case of Coccus cacti ”

“ From this result two things, or, rather, the same injurious effect on the plant is produced in two ways. First, the honeydew itself, being, as stated, of a glutinous nature, tends to stop up and choke the stomata (or, in plain English, the breathing-orifices of the leaves) and so retard the growth of the tree. Secondly, the honeydew, being of a saccharine nature, is especially attractive to fungoid growths, and these fungi, rapidly increasing, tend still more to choke the leaves and hamper the proper functions of the tree. ”

“ The Coccididæ, like all Homoptera, produce great numbers of young; but their increase does not appear to be as rapid as that of some other families. The numbers of some Aphididæ or Aleurodidæ produced from a single female in the course of a single year have been calculated at hundreds of thousands, if not millions; and as many as eleven generations have been produced in little over half a year. Coccids, however, as a rule, do not propagate at this alarming rate. ”

“ Unfortunately, Icerya is not only a frequent breeder, but also the most destructive insect of the family in New Zealand.
The number of young produced by each female seems also to vary. The author has counted from 30 to 80 eggs in the puparium of Mytilaspis pomorum; as many as 350 in the ovisac of Icerya purchasi, and about the same number of Cœlostoma zælandicum: and a female of Lecanium hesperidum examined in spring contained 93 embryos. ”

“ A more important check on the increase of many Coccids is afforded by the indirect action of minute hymenopterous insects, which make use of them as receptacles for their eggs. This plan is adopted by several Hymenoptera, of the families Chalcididæ, Ichneumonidæ, Proctotrupidæ, &c. They do not devour their prey; they allow it to live that they may live on it. By means of their long ovipositor they pierce its body, and deposit in it an egg. As the victim grows the egg matures, changes into a larva, and still remains in the body of the Coccid ”

“ The male puparia frequently occur massed in great numbers, and covered with white hairs and fluff.
Adult female rather elongated, oval, or somewhat pear-shaped; the body corrugated, the cephalic portion smooth. At each side, on a level with the rostrum, or a little above it, is a protruding lobe, which is characteristic. Colour, light-yellow. Abdomen ending in two lobes, not prominent, and with a depression between them; beyond the lobes are many serrations, with small lobelike projections and spiny hairs. Five groups of spinnerets: uppermost group with five to eight orifices [L] ”

“ Adult females enclosed in a sac, or test, of secretion so closely felted as to appear waxy; round the edge of the sac a double fringe of glassy tubes; apodous; antennæ absent. Anal tubercles present in all stages.
The differences between this genus and Asterolecanium (see above under Lecanidinæ) are not to be made out from external examination of the sac, nor without close investigation. It is possible, indeed, that Asterolecanium should be removed from the Lecanidinæ and united with Planchonia. ”

“ In many cases they exude, in the form of minute globules, a whitish, thick, gummy secretion, answering probably to the "honeydew" of the Aphididæ. This secretion drops from them on to the plant, and from it grows a black fungus, which soon gives an unsightly appearance to the plant. This fungus or "smut" is an almost invariable indication that a plant is attacked by insects, [C] and may, indeed, give a useful warning to tree-growers. It is not, however, produced in appreciable quantities by all species.
[C] Not necessarily a Coccid insect: the fungus may also grow on the honeydew of Aphis ”

“ Habitat—On Olearia Haastii, Botanical Gardens, Wellington. This is an alpine plant cultivated in the Gardens, and the insect probably came with it from the mountains.
This species is distinguished from E. spinosus by the great number of spiny spinnerets on the dorsum of the female and by the tubular character of the fringe.
The curious and exceptional character of a tibia shorter than the tarsus in the adult female, as observed above, is found only in this genus and some Acanthococcidæ. ”

“ There are several single spinnerets. The adult insect, before gestation, nearly fills the space covered by the second pellicle; after gestation it shrinks up into very small compass at the cephalic end of the puparium.
Adult male unknown.
Habitat—On Brachyglottis repanda; Panax arboreum, Port Hills, Canterbury.
Differs from the European species, F. pellucida (Targioni) , in its extremely-minute size, in the serrations of the abdomen, and the number of its hairs. Also in F. pellucida the young female larva has two tubercles between the antennæ, which are not seen in F. minima. ”

“ Many of those who profess to know all about destroying "scale"—especially if they belong to that class which prides itself upon being "practical men"—being generally quite ignorant of the habits and life-history of the insects, are satisfied when they « 26 » have tried some rule-of-thumb plan which seems to kill most of the adult insects, not dreaming that they have left the eggs unharmed and ready to send forth a fresh swarm at hatching-time. There is another obstacle which often prevents success in eradicating "scale." This is the difficulty of making sure of the effects of any remedy. ”

“ It has been already observed that the killing of the eggs is absolutely necessary for thorough clearing-away of the insects; and, to quote again the words of Mr. Hubbard, kerosene is "almost the only substance which will with certainty kill the eggs without at the same time destroying the plant."
But precautions must not be neglected. Persons who recklessly use any remedy, or who apply it too thickly or in too strong proportions, must expect their trees to suffer. Nor must the weather and the time of the year be overlooked. Winter is the best season for all remedies ”

“ The female in the second stage is also convex above, flat below, but is less thick than the adult, and has not the corrugations. General form elongated-oval; the abdominal lobes are not, as usual, smooth, but approach by irregularity the anal tubercles of the Coccidinæ, and like them bear a few hairs. The anal ring has eight hairs. Antennæ of six joints. Feet normal; digitules as in adult. On the skin are several scattered, circular, very minute spinnerets; the stigmatic spines are long and conspicuous, and along the edge runs a row of conical hairs or spines. ”

“ Subdivision I.—LECANODIASPIDÆ, Targioni-Tozzetti.
Female insects exhibiting in all stages the abdominal cleft and lobes. Larvæ free, naked, active. Females after the first metamorphosis constructing over themselves a carapace, shield, « 64 » or (as called herein) test, of glassy, waxy, or horny secretion. Test apparently homogeneous, really in most cases formed of aggregated segments over the insect, and prolonged beyond the body in a flat single fringe of separate, more or less triangular or quadrate, segments. Fringe not always present or conspicuous in all stages. ”

“ This insect lives on the leaves of cactus. Amongst the New Zealand species described in this work will be found one, Dactylopius alpinus, which produces a red dye similar to, though probably not equal to, cochineal. Before the discovery of aniline dyes it might possibly have been worth while to cultivate this insect for its dye; but this would scarcely answer now.
The Coccididæ are, in some parts of the world, very injurious to vegetation. They seem to affect principally the warmer temperate regions. ”