. Entomologia economica per gli agricoltori e i coltivatori di frutta e per uso come un libro di testo nelle scuole agrarie e collegi;. Insetti e parassiti. 376 un'entomologia economica. Figura il legno si asciuga, diventa inadatto per cibo e, come l'insetto è incapace di viaggiare, è starves a morte. Nel caso di Cephus pygrnceus, gli insetti noioso nel frumento, trascorrono l'inverno sia in basso la levetta infestati, cioè nella stoppia-o nel terreno appena al di sotto della superficie, sia larvale o condizione di pupa. Il ])roper remedy è masterizzare il file .la stoppia non appena dopo il raccolto come possibile, o di aratro

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. Economic entomology for the farmer and the fruit grower, and for use as a text-book in agricultural schools and colleges;. Insects; Pests. 376 AN ECONOMIC ENTOMOLOGY. Fig the wood dries, becomes unsuitable for food, and, as the insect is incapable of travelling, it starves to death. In the case of Cephus pygrnceus, the insects boring in wheat, they spend the winter either low down in the infested stalk—i.e., in the stubble—or in the soil just below the surface, in either the larval or pupal condition. The ])roper remedy is to burn the .stubble as soon after harvest as possible, or to plough it under deeply. This destroys the in- sects and results in preventing injury the year following. We have no means of reaching the larva while it is actually working in the stem of the plant. The remedy is radical, and were it universally resorted to, would need to be applied only at inter- vals of several years. The "gall-flies, " belonging to the family Cynipidcs, are curi- ous creatures. They resemble minute wasps in form, and gen- erally have a very short, chunky body, which is often compressed and joined to the abdomen by a very slender petiole or stalk, in sharp contrast to the species heretofore written of These gall-flies are mostly true parasites on plants. They derive their common name from the fact that they produce swellings, protu- berances, or "galls" of great variety on vegetable tissues ; some- times on leaves, on twigs, on trunks, or even on roots ; and perhaps, of all others, the oak is the favorite of the insects of this family, bearing the greatest variety of galls on all its parts. I say these insects are mostly plant parasites, and intend to ex- press by this that they do not actually eat the infested vegetable tissue. The irritation caused by the larva induces an abnormal growth in the part of the plant infested, and in a cell in this growth it has its home. Here the insect reaches maturity with-. Cephus pys;m(sns, wheat-stem saw-fl

Parole chiave associate all'immagine

• bookcentury1900
• bookdecade1900
• booksubjectinsects
• bookyear1906