Lichtenstein has established the fact that from the egg of the Aphis of Pistachio galls, Anopleura lentisci, is hatched an apterous insect (the gall-founder), which gives birth to young Aphides (emigrants), and that these, having acquired wings, fly to the roots of certain grasses (Bromus sterilis and Hordeum vulgare), and by budding underground give rise to several generations of apterous insects, whence finally comes a winged brood (the pupifera).
In many cases the punctures of Aphides and Coccideae are shown to be responsible for such exudations, and at least one instance is known where a FungusClaviceps-causes it.
Species of aphides may be removed by tobacco infusion, soapsuds or other solutions.
Some aphides live only on one species of plant, others on two or more plants.
If, however, the food-plant is grown in a conservatory where protection against cold is afforded, the aphides may go on reproducing agamogenetically without cessation for many years together.
Includes the cicads, aphides and scale-insects (see Hemiptera).
Slug-worms or saw-fly larvae require treatment by washing with soapsuds, tobacco and lime-water or hellebore solution, and Aphides by syringing from below and removing all surplus young twigs.
Warren has shown by direct observation that the correlation between brothers among the broods produced parthenogenetically by one of the Aphides has a value not far from the 2 observed in sexually produced brethren (Biometrika, vol.
His attention having been drawn to the blighting of the young shoots of fruit-trees, which was commonly attributed to the ants found upon them, he was the first to find the Aphides that really do the mischief; and, upon searching into the history of their generation, he observed the young within the bodies of their parents.
Saprophytic bacteria can readily make their way down the dead hypha of an invading fungus, or into the punctures made by insects, and Aphides have been credited with the bacterial infection of carnations, though more recent researches by Woods go to show the correctness of his conclusion that Aphides alone are responsible for the carnation disease.