Leiomyza in North America (Dipt., Drosophilidae.).

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Injurious Insects

In the following pages the life history of several of our most injurious insects is explained, and the best remedies at present known are mentioned. It is hoped that by the aid of the illustrations all the species treated of can be readily recognized. A careful perusal of the article on insecticides ought to suggest practical ways of treating many insects which are not specifically mentioned in the Bulletin. In nearly all cases, our suggestions as to remedies are based on our own experiments and observations

The New Insectary

Recognizing the necessity of facilities for rearing insects in a situation where alt external conditions could be controlled, as well as of a suitable place for keeping the collections and apparatus of the department the board of trustees last year authorized the construction of a building for the entomological department. This was occupied about June 25. It is a structure 16x32 feet in size, with wing 12 feet square. In the main part is the general office and work room, 16 feet square, a well finished room, provided with desk, tables, balances, shelves for collections, etc. Here are kept a general collection of all orders of insects, chiefly collected in this locality; some economic collections, showing the transformations, work and parasites of some of the common injurious insects; samples of various insecticides, and a few bee supplies. The rearing-room, or insectary proper, occupies the remainder of the main part of the building. It is an unfinished room with dirt floor, lighted by five large windows. It is as yet but partially fitted up, owing to the fact that the rearing season was almost past when we moved into the building last spring. Breeding cages and other devices for this line of work will be in operation this year. The wing on the east side of the main building is devoted to bee-keeping and storage of machinery, etc. The bees are placed on a low shelf along the side of the room, the faces of the hives toward the outside. Horizontal slits through the wall, one immediately in front of each hive, give the bees egress. This arrangement is called a house apiary, and presents several advantages, in our circumstances. The hives are safe from violent winds and are in a very convenient place for working with them, as by .nearly closing the door the room can be darkened until the bees will not fly in it

The Cut-Worm

The work of the department for the last year has been of two kinds. First, the attempt to keep in check the injurious insects of the farm, garden, and tree plantations. Second, such experiments and original investigations as could be made. The progress of events showed early in the season that cut-worms were among our worst enemies, and later reports as given further on, show them to be quite generally distributed through the State. They have, therefore, received as much attention as circumstances would allow. Notes more or less extended were made on various other pests in their season but this group has been selected as our chief subject of study. To speak of the cut-worm in a general way may be intelligible enough to most people, but still it should be remembered that there are many species. Probably as many as twenty-five are found in our State, though about half a dozen species compromise a majority of the worms. While there is a general similarity of habits among these common species, it may yet be found that the differences which exist are sufficient to require widely different methods in the extermination of the worms

Binding Energy of Hydrogen-Like Impurities in Quantum Well Wires of InSb/GaAs in a Magnetic Field

The binding energy of a hydrogen-like impurity in a thin size-quantized wire of the InSb/GaAs semiconductors with Kane’s dispersion law in a magnetic fieldBparallel to the wire axis has been calculated as a function of the radius of the wire and magnitude ofB, using a variational approach. It is shown that when wire radius is less than the Bohr radius of the impurity, the nonparabolicity of dispersion law of charge carriers leads to a considerable increase of the binding energy in the magnetic field, as well as to a more rapid growth of binding energy with growth ofB

Untangling the effects of overexploration and overexploitation on organizational performance: The moderating role of environmental dynamism

Because a firm's optimal knowledge search behavior is determined by unique firm and industry conditions, organizational performance should be contingent oil the degree to which a firm's actual level of knowledge search deviates from the optimal level. It is thus hypothesized that deviation from the optimal search, in the form of either overexploitation or overexploration, is detrimental to organizational performance. Furthermore, the negative effect of search deviation oil organizational performance varies with environmental dynamism: that is, overexploitation is expected to become more harmful. whereas overexploration becomes less so with all increase in environmental dynamism. The empirical analyses yield results consistent with these arguments. Implications for research and practice are correspondingly discussed