This section is from the book "The Gardener V3", by William Thomson. Also available from Amazon: The New Organic Grower: A Master's Manual of Tools and Techniques for the Home and Market Gardener.
Female specimens and their eggs, a and a, antennse; b and b, horns or suckers; c, egg plainly visible in the body of the insect; d, the egg; f, winged form of the insect. All greatly magnified.
In some localities of the south of Frauce the Vines are suffering from the ravages of a destructive insect, which has lately been noticed for the first time. M. E. A. Carriere has just published in the ' Revue Horticole' an extract from an article which M. J. E. Planchon contributed a short time ago to the 'Comptes-Rendus de l'lnstitut' (1868, p. 588). Here is the passage from the 'Revue': -
"I will here give a brief resume of all I learnt about the habits of the Phylloxera vastatrix from a series of observations made on the spot, in three short visits to the south of France; also all I noticed with reference to the specimens which I kept in glass bottles during forty consecutive days.
"Its best-known form is that in which no trace of wings can be discovered. When the insect is about to lay its eggs (that is, in its adult female state), it forms a small ovoid mass, having its inferior surface flattened, its dorsal surface convex, being surrounded by a kind of fillet, which is very narrow when it touches the thoracic part of its body, which (formed by five rather indistinct rings) is hardly separated from its abdominal part of seven rings.
"Six rows of small blunt tubercles form a slight protuberance on the thoracic segments, and are found very faintly marked on the abdominal segments. The head is always concealed by the anterior protuberance of the buckler; the antennae are almost always inactive. The abdomen, often short and contracted, becomes elongated towards laying-time, and there can be easily seen one, two, or sometimes three eggs, in a more or less mature state.
"The egg sometimes retains its yellow colour for one, two, or three days after it has been laid; more often, however, it changes to a dull-grey hue. From five to eight days generally elapse before it is hatched. The duration of this period depends a good deal on the temperature. The quantity of eggs, and the rapidity with which they are produced, are probably determined by a variety of circumstances - the health of the insect, the quantity of nourishment it is able to obtain, the weather, and perhaps other causes. A female which had produced six eggs at eight o'clock a.m. on the 20th of August, had fifteen on the 21st at four p.m. - that is, she laid nine in thirty-two hours. Other females lay one, two, or three eggs in twenty-four hours. The maximum quantity is thirty in five days. The eggs are generally piled up near the mother without any apparent order, but she sometimes changes her position so as to scatter them all around her. They have a smooth surface, and adhere lightly to each other by means of a slimy matter which attaches to them.
"Hatching takes place through an irregular and often lateral rent in the egg, the empty and crumpled membrane being found among the other eggs in different stages of hatching.
"During the first period of their active life - two, three, four, or five days, as the case may be - the insects are in an erratic state. They creep about as if they were seeking for a favourable situation. Their movements are more rapid than those of adults. They appear to inspect, as it were, with their antennae the surface they travel over. The movements of the antennae are generally alternative, and, if the comparison may be pardoned, are not unlike the two sticks of a blind man, which he uses to explore the ground he is about to tread.
"After a few days of this errant life, the young insects seem to fix upon a spot to settle in. Most frequently this is a fissure in the bark of a Vine, where their suckers can be easily plunged into the cellular tissue, full of saccharine matter. If you make a fresh wound on the root by cutting off a little piece of the bark, you may see the 'Pucerons' range themselves in rows around the wound, and, once fixed, they apply to the root their antennae, which appear like two small divergent horns. At this period of their life, about the 13th or 14th day after their birth, they are more or less sedentary; but they change their places if a new wound is made on the root, which promises a fresh supply of food.
"What sense is this which directs these subterraneous ' Pucerons ' towards the place which is most suitable for them? It cannot be sight, as their eyes are merely coloured spots, and they creep as if they were blind. It cannot be hearing, because they seek no prey but a vegetable tissue. It is probably the sense of smelling; and one may well ask if the nuclei which appear enshrined in the last articulations of the antenna) are not the organs of this function, the seat of which has been so much disputed? Among these non-adult insects, attached by their suckers to the Vine-root, are seen, here and there, some of middle size. Their colour is a deeper orange, the abdomen shorter and more squarely formed. These individuals are more sedentary than the others. I have sometimes imagined they might be wingless (apterous) males of the species; but as nothing has happened to confirm this very problematical hypothesis, and as I have seen undoubted females much resembling these examples in colour and form, I incline to the belief that there are no sexual differences among them. A kind of double moult precedes the adult state.