1172 EXPERIMENT STATION RECORD. 



This insect appears on the roots of the Norway spruce, and, when present in large 

 numbers, sucks the juice from the roots to such an extent that the trees are greatly 

 weakened, or, in some cases, killed outright. In combating this pest, the best 

 results have been obtained from the use of carbon bisulphid mixed with molasses 

 and placed in the soil about the roots of infested trees. The molasses serves to hold 

 the carbon bisulphid for some time, allowing it gradually to escape and produce its 

 effect upon the insects. The insecticide may be injected into the soil by means of a 

 syringe or placed in a furrow around the trunk. 



The number of annual generations among" the bark beetles, E. Knoche 

 (Naturw. Ztschr. Land u. Forstw., 3 (1905), Nos. 9, pp. 353-368; 10, pp. 401-415).— 

 The literature relating to the biology of various species of bark beetles is critically 

 reviewed. 



The author concludes from the study of literature and from his own observations 

 that the question whether a given species of bark beetle produces 1 or 2 generations 

 annually depends not so much upon the species as upon the temperature of the 

 locality where the beetle is found. Nevertheless under given conditions different 

 species do not vary in this respect, but each one shows the same number of genera- 

 tions from year to year. 



Tomicus typographus, O. Nusslin (Naturw. Ztschr. Land u. Forstw., 3 (1905), 

 Nos. 11, pp. 450-468; 12, pp. 481-493, fig. 1). — This insect is described in its various 

 stages with special notes on its occurrence in Herrenwies and Pfullendorf in 1905. 

 In order to control this beetle it is very desirable that infested trees should be cut 

 and removed from the forest before the beetles have emerged. This and the main- 

 tenance of trap trees are about the only practical remedies for the control of the 

 pest. 



Pissodes harcyniae, G. Fuchs (Naturw. Ztschr. Land u, Forstw., 3 (1905), No. 12, 

 pp. 507, 508, pi. 1). — This insect is reported as occurring in large numbers in June on 

 pine trees. As a result of the injury due to the beetle, infested trees became subse- 

 quently diseased through the attacks of Trametes pint. 



Lophyrus similis, W. Baer (Naturw. Ztschr. Land u. Forstw., 4 (1906), No. 2, 

 pp. 84-92, figs. 3). — This saw fly is described with notes on some related species and 

 on anatomical features which serve to distinguish it from the other species. Par- 

 ticular attention is given to the biological and morphological differences between 

 L. similis and L. pini. 



Progress made in exterminating the fever tick in North Carolina, T. 

 Butler (Raleigh: N C. Dept. Agr., 1906, pp. 4, figs. 3).— The attention of cattle 

 raisers is called to the fact that during the past 4 years 10 counties in North Carolina 

 have been freed from cattle ticks and placed above the Federal quarantine line. The 

 author considers that his experiments have demonstrated the feasibility of extermi- 

 nating cattle ticks in all sections where stock laws prevail. It is believed that the 

 ticks may be exterminated at a smaller cost than the annual loss due to cattle ticks 

 in the affected regions. 



Fowl tick experiments, F. H. Robertson (Jour. Dept. Agr. West. Aust., 12 (1905), 

 No. 6, pp. 561-563). — It was found that fowl ticks remain alive at least 2 years and 3 

 months without the presence of any fowls from which to derive nourishment. In 

 these experiments the ticks were maintained in small pill boxes which were practically 

 air tight. In the nymph stage ticks may live for 2 months without food. 



A classification of the mosquitoes of North and Middle America, D. W. 

 Coquillett (U S. Dept. Agr., Bur. Fnt. Bui. 11, tech. ser., pp. 31, fig. l).—On 

 account of the requests received by this Department from students of entomology, 

 physicians, and sanitary officials regarding the identification of mosquitoes in vari- 

 ous parts of the country, the present bulletin is prepared to furnish information along 

 this line. The external anatomy of mosquitoes is briefly described, together with 

 notes on the subfamilies, a table for identifying these subfamilies, and also analytical 



