. Bollettino. Insetti; pesti di insetto; Entomologia; insetti; pesti di insetto; Entomologia. 14 frutta decidue insetti e insetticidi. Thrips sono in terra tutti del tempo di tMs, e per la maggior parte alla portata del coltivatore, ma maturo e arrivare sugli alberi in marzo e aprile, prima della primavera la coltivazione è iniziato. Nemici naturali. La pera thrips è largamente protetto da preaaceous ordinario e insetti parassiti, perché si spende tanto tempo nascosto nel terreno. Un parassita successfid deve in modo parallelo la vita del suo ospite e non abbiamo riscontrato nessun insetto che segue quindi il p

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. Bulletin. Insects; Insect pests; Entomology; Insects; Insect pests; Entomology. 14 DECIDUOUS FRUIT INSECTS AND INSECTICIDES. Thrips are in the ground all of tMs time, and for the most part within reach of the cultivator, but they mature and arrive on the trees in March and April, before spring cultivating is begun. NATURAL ENEMIES. The pear thrips is largely protected from ordinary preaaceous and parasitic insects, because it spends so long a time hidden away in the ground. A successfid parasite must in a way parallel the life of its host, and we have found no insect which thus follows the pear thrips. Raphidians, or snake flies, their commonest enemies in the vSanta Clara Valley, feed rather on the younger forms than on the fully developed insects, and they do not appear early enough in the spring to constitute an effective check to the pest. To be competent thrips killers they would have to feed on other insects for perhaps ten months in the year and then, when thrips appear, suddenly change their diet and later, after tlu"ips have gone into the ground, as suddenly change back again to aphides or to something else. Such feeding habits are not to be expected in a nredaceous species. Ants were at one time thought to be doing much good as an enemy of the thrips. A certain orchardist brought in an ant with a thrips impaled in its jaws—the evidence complete. After a careful investi- gation, however, it was found that only a very small percentage of ants were actually killing thrips. Four hundred ants were examined as they descended a thrips-infested tree. Twelve of these carried something in their jaws and only 4 of these objects were thrips. Thus only 1 per cent of the ants on the tree were actually killing thrips aiul carrying them down. It has been a common observation among orchardists, however, that tlmps are not common where ants are unusually abundant. Spiders and mites are active enemies of thrips. In some of our breeding cages almost all of the thrips

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• bookcentury1900
• bookdecade1900
• booksubje
• booksubjectentomology