On a Polyhedral Disease of Trichiocampus viminalis (Fall.) Larvae (Hymenoptera: Tenthredinidae)

1959 ◽  
Vol 91 (6) ◽  
pp. 379-381 ◽  
Author(s):  
W. A. Smirnoff ◽  
R. Béique
Keyword(s):  
United States ◽  
British Columbia ◽  
Populus Nigra ◽  
Quebec City ◽  
Eastern United States ◽  
Eastern Canada ◽  
The Past ◽  
The North ◽  
North Eastern

The poplar sawfly, Trichiocampus viminalis Fall., is indigenous to Europe, where it is common and widespread, but is also prevalent in the north-eastern United States, Eastern Canada and British Columbia. For the past five or six years it has caused serious defoliation to Populus nigra and P. deltoides in the vicinity of Quebec City.

A Field Key to the North American Species of Hylobius (Curculionidae)

1961 ◽  
Vol 93 (7) ◽  
pp. 501-502 ◽  
Author(s):  
R. J. Finnegan
Keyword(s):  
United States ◽  
North American ◽  
Economic Importance ◽  
North American Species ◽  
Eastern United States ◽  
Eastern Canada ◽  
The North

There are five known North American species in the genus Hylobius; H. pales (Hbst.), H. congener Dalla Torre, H. pinicola (Couper), H. radicis Buch., and H. warreni Wood. In recent years four of these species have increased considerably in economic importance in central and eastern Canada and the eastern United States; H. pales and H. radicis attacking pines and H. pinicola and H. warreni attacking spruces and pines. H. congener occurs only in small numbers and little is known about its ecology. It is important, therefore, to be able to separate these species readily in the field.

A Sibling Species Group of Hydractinia in the North-Eastern United States

1989 ◽  
Vol 69 (4) ◽  
pp. 857-874 ◽  
Author(s):  
Leo W. Buss ◽  
Philip O. Yund
Keyword(s):  
United States ◽  
Sibling Species ◽  
Host Species ◽  
Larval Dispersal ◽  
Phylogenetic Reconstruction ◽  
Species Group ◽  
Eastern United States ◽  
The North ◽  
North Eastern ◽  
Symbiotic Organisms

Many symbiotic organisms are narrowly distributed on one or a few host species. These associations are intriguing, as they invite the development of hypotheses regarding the pattern and process of speciation and serve as laboratories for the testing of methods of phylogenetic reconstruction (Kraus, 1978; Futuyma & Slatkin, 1983; Stone & Hawks worth, 1986). The evolution of host-specificity in the sea may be expected to be severely constrained by the difficulty of achieving reproductive isolation in taxa whose gametes are freely released into the water column and/or whose larvae are potentially widely distributed (Scheltema, 1977). Yet this difficulty may well be overestimated, given the recent demonstrations of limited gamete (Pennington, 1985; Yund, in press) and larval dispersal (Knight-Jones & Moyse, 1961; Ryland, 1981; Olsen, 1985; Jackson & Coates, 1986; Grosberg, 1987). Indeed, if gamete and larval dispersal are as limited as has recently been contended (Jackson, 1986), local isolation of populations may be a routine occurence, offering repeated opportunities for speciation.

scholarly journals The recent development of melanism in the larvæ of certain species of Lepidoptera, with an account of its inheritance in Selenia bilunaria esp

1932 ◽  
Vol 111 (770) ◽  
pp. 188-200 ◽  
Keyword(s):  
United States ◽  
Central Europe ◽  
The United States ◽  
Eastern United States ◽  
Evolutionary Processes ◽  
Number Of Species ◽  
The North ◽  
North Eastern ◽  
Geometrid Moth ◽  
State Of Affairs

One of the most remarkable evolutionary processes, the more striking since it has occured before our eyes, has been the rise and spread of melanism and melanochroism amongst the Lepidopetera. Commencing about 1850 in the Manchester area in England with the Geometrid moth Amphidasys betularia L., which yielded the black form carbonaria Jord. ( doubledayaria Mill.), this development has proceeded so rapidly, and become so widespread, that now there is scarcely a country in Northern and Central Europe which does not produce its quota of melanic insects. Moreover, the same state of affairs exists in the North-Eastern United States, although there the number of species affected, up to the present, is not so great as in Europe. Another important feature about these changes lies in the circumstance that, almost uniformly, in Europe and in the United States, the first species to exhibit melanism in any given area have been Amphidasys betularia and Tephrosia crepuscularia . From the beginning, the Geometridæ, more especially the subfamily Boarmiinæ, have provided not only the bulk of the melanic varieties, but also the greatest numbers of individuals. In many areas, as for example in the case of A. betularia and Y psipetes trifasciata , only black examples occur. Nevertheless, other groups include species which have gone black; for instance, the Noctuidæ present black forms of Aplecta nebulosa Hufn., the Cymatophoridæ of Cymatophora or F., the Arctiidæ of Spilosoma lubricipeda L., the Gelechiidæ of Chimabacche fagella F., and so on.

Axial Inlet Conversion to a Centrifugal Compressor With Magnetic Bearings

1992 ◽  
Author(s):  
Tom Novecosky
Keyword(s):  
United States ◽  
British Columbia ◽  
Natural Gas ◽  
Centrifugal Compressor ◽  
Axial Compressor ◽  
Magnetic Bearings ◽  
Operating Costs ◽  
Eastern Canada ◽  
The Past ◽  
Compressor Efficiency

NOVA’s Alberta Gas Transmission Division transports natural gas via pipeline throughout the province of Alberta, Canada, exporting it to eastern Canada, United States and British Columbia. It is a continuing effort to operate the facilities and pipeline at the highest possible efficiency. One area being addressed to improve efficiency is compression of the gas. By improving compressor efficiency, fuel consumption and hence operating costs can be reduced. One method of improving compressor efficiency is by converting the compressor to an axial inlet configuration, a conversion that has been carried out more frequently in the past years. Concurrently, conventional hydrodynamic bearings have been replaced with magnetic bearings on many centrifugal compressors. This paper discusses the design and installation for converting a radial overhung unit to an axial inlet configuration, having both magnetic bearings and a thrust reducer. The thrust reducer is required to reduce axial compressor shaft loads, to a level which allows the practical installation of magnetic bearings within the space limitations of the compressor (Bear and Gibson, 1992).

scholarly journals Trees, Shrubs and Vines for the North-eastern United States

Nature ◽  
1946 ◽  
Vol 158 (4022) ◽  
pp. 772-772
Author(s):  
N. K. GOULD
Keyword(s):  
United States ◽  
Eastern United States ◽  
The North ◽  
North Eastern
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