Entomology: With Special Reference to Its Biological and Economic Aspects

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P. Blakiston's Son & Company, 1906 - 485 páginas
 

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Página 226 - That the imitators are always less numerous in individuals. " 4. That the imitators differ from the bulk of their allies. "5. That the imitation, however minute, is external and visible only, never extending to internal characters or to such as do not affect the external appearance.
Página 456 - Notes on the Mosquitoes of the United States : Giving Some Account of Their Structure and Biology, with Remarks on Remedies.
Página 234 - Apatetic colours. — Colours resembling some part of the environment or the appearance of another species. II.
Página 313 - Washington, more than 97 per cent of the caterpillars of one of our most important shade-tree pests were destroyed by parasitic insects, to the complete relief of the city the following year. The Hessian fly, that destructive enemy to wheat crops in the United States, is practically unconsidered by the wheat growers of certain States, for the reason that whenever its numbers begin to be injuriously great its parasites increase to such a degree as to prevent appreciable damage. The control of a plant-feeding...
Página 383 - Adams recognizes ten criteria, aside from palaeontological evidence, for determining centers of dispersal : 1. Location of greatest differentiation of a type. 2. Location of dominance or great abundance of individuals. 3. Location of synthetic or closely related forms (Allen). 4. Location of maximum size of individuals (RidgwayAllen).
Página 113 - ... other hand, the focal length of the lens limits the distance at which a distinct view can be obtained. Of the various forms of Insects examined, the best eye would give a picture about as good as if executed in rather coarse wool-work, and viewed at a distance of a...
Página 291 - The fact that, with the exception of the indigo-bird, the species whose records in the orchard were compared with those made elsewhere had eaten in the former situation as many caterpillars other than canker-worms as usual, simply adding their canker-worm ratios to those of other caterpillars, goes to show that these insects are favorites with a majority of...
Página 325 - KINDS OF BEES COMPOSING A COLONY— BEE PRODUCTS AND DESCRIPTION OF COMBS— DEVELOPMENT OF BROOD. KINDS OF BEES IN A COLONY. Each colony of bees in good condition at the opening of the season contains a laying queen and some 30,000 to 40,000 worker bees, or six to eight quarts by measurement. Besides this there should be four, five, or even more combs fairly stocked with developing brood, with a good supply of honey about it. Drones may also be present, even several hundred in number, although it...
Página 446 - Butterflies : their Structure, Changes, and Life-Histories, with Special Reference to American Forms. Being an Application of the " Doctrine of Descent
Página 232 - ... that he did not find a single instance of instinctive avoidance, but that the result of his observations is that " in the " absence of parental guidance, the young birds have to learn " for themselves what is good to eat and what is distasteful, " and have no instinctive aversions.

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