ECONOMIC ZOOLOGY — ENTOMOLOGY. 60 



Uiscussion on the spread of plague, C. J. Martin (Brit. Med. Jour., 1911, 

 No. 265-'i, pp. 12-fi9-1261, figx. 7). — Accounts are given of the transmission of 

 plague by fleas, including a report of cage experiments; experiments in 

 specially constructed brick animal houses from which fleas could be practically 

 excluded ; the fate of the plague bacillus in the body of the rat flea, and the 

 mechanism by means of wliich the flea infects a healthy animal ; the approxi- 

 mate proportion of fleas in the stomachs wherein multiplication of bacilli talces 

 place; and similar topics. 



An attack of Hylesinus piniperda and H, minor in upper Dalama, Sweden, 

 T. Laoerberg ( ^kogsvardsffir, Tidftkr., 1911 Almunna Dclm, Xo. 11, pp. 381-393, 

 figs. 7). — An illustrated account of the injury caused by these scolytids, in- 

 cluding a bibliography of 12 titles. 



The southern pine beetle and its control, "W. E. Hinds (Alnhamn Col. fita. 

 Circ. 15, pp. -'/3-.j8, figs. J/). — This circular embodies most of the information 

 relating to Dendroctonus frontalis given in Farmers' Bulletin 476 (E. S. R., 26, 

 p. 476), together vt'ith other data. This pest is causing the death of pine trees 

 of various species in increasing numbers, in Alabama. 



The movement of the Mexican cotton boll weevil in 1911, W. D. Huntee 

 (Z7. S. Dcpt. Agr., Bur. But. Circ. 1 ',IJ. pp. J,, fig. /).— During the season of 1911 

 the boll weevil was greatly reduced in numbers throughout its entire range, as 

 tlie result of a combination of climatic influences extending over a period of 

 about 3 years. So unfavorable were the conditions that the insect was exter- 

 minated in an area covering about 23,000 square miles in the northwestern 

 portion of Texas and the western portion of Oklahoma. 



Notwithstanding this great reduction in 1911, consideralile advance was made 

 to the East and Nortli when the dispersion movement began in August. As a 

 result of tliis extensive disi^ersion much of the territory it had lost in Texas 

 and Oklahoma was regained, and P^'lorida became invaded for the flrst time. 



A map is given which shows the dispersion of the cotton boll weevil from 1892 

 to 1911. 



The insect enemies of the cotton boll weevil, W. D. Pierce, R. A. Cushman, 

 and C. E. IIood {U. S. Dept. Agr., Bur. Ent. BuL 100, pp. 99, pis. 3, figs. 26.).— 

 The authors' investigations are here presented in 3 parts, part 1 (pp. 12-39) 

 dealing with the status of the cotton boll weevil and its enemies; part 2 (pp. 

 39-83) with the biological complex; and part 3 (pp. 83-96) with the economic 

 application. A bibliography of 54 titles is appended. 



The authors consider the control of the boll weevil by insect enemies to be 

 sufficiently great to give it a high rank in the struggle against the pest. "A 

 considerable portion of the insect control would not be accomplished by any 

 other factor; hence it is by no means to be neglected. The number of species 

 of insects attacking the developing stages is 49. The control in any given place 

 consists of the combined work of several different species. Places having the 

 largest number of controlling insects have the highest percentage of control. 

 In many places insect control is considerably greater than climatic control or 

 than any other class of factors. The average insect control is 20 per cent of 

 all immature stages or two-flfths of the entire natural control. 



" The cotton leaf-worm is a valuable enemy of the boll weevil when it 

 defoliates the cotton after September 1, a date beyond which new squares can 

 not be expected to mature. It kills many weevils by starvation, kills many 

 others while consuming the squares, and finally forces a premature hibernation 

 which is generally fatal. 



" The amount of control due to the various factors at work in any given 

 place should be increased if possible. Parasites can be introduced into new 



