240 



oviposition generally occurs so late in the season that the injury 

 caused by the larvae only takes place after the mature nuts have fallen, 

 whereas on Persian nuts oviposition occurs earlier, and the activities 

 of the larvae arrest the development of the nut and the kernel becomes 

 unfit for use. 



The various stages of this Trypetid are described ; the eggs apparently 

 hatch in about seven to ten days ; the larvae mine in the husk and 

 often remain in this position until the hard frosts occur ; during the 

 warmer periods of the late autumn they enter the ground for pupation, 

 in which stage the winter is passed, at a depth of about half an inch 

 to several inches from the surface. Most of the adults emerge the 

 following summer, but some of the pupae remain in that stage for a 

 second winter. In West Virginia the adults emerge about the middle 

 of July. In rearing jars they emerged from 16th July to 8th September, 

 covering a period of 55 days. 



The natural enemies of R. suavis are a Hymenopterous parasite, 

 Aphaereta auripes. Prov., reared from pupae in Massachusetts, and a 

 species of Lopidea found feeding on the eggs. During experiments in 

 1920, trees bearing heavy crops of nuts were sprayed with 3 lb. lead 

 arsenate paste to 50 U.S. gals, water on 10th August, this treatment 

 apparently reducing the infestation. Adults confined in wire screen 

 cages fed readily on sweetened water containing sufficient lead 

 arsenate to give it a milky appearance, but they succumbed very slowly 

 to the poison. Further experiments are necessary before this method 

 can be advocated as efficient against R. suavis. 



McCoNNELL (W. R.). Rate of Multiplication of the Hessian Fly. — 



U.S. Dept. Agric, Washington, D.C., Bull. 1008, 15th November 

 1921, 8 pp. [Received 9th March 1922.] 



An investigation has been made into the rate of multiplication of 

 Mayetiola {Phytophaga) destructor, Say (Hessian fly), largely as a 

 basis for estimating the efficiency of the various species of parasites. 

 The rate of multiplication, which is recorded in a series of tables, is 

 very different in the two principal generations, the spring generation 

 laying an average of 230 eggs per female, while the autumn generation 

 lays about 285 per female. The capacity for reproduction also varies 

 with a number of other factors, such as date of sowing, number of 

 puparia per tiller, etc., so that the rate of multiplication will vary from 

 year to year and even from field to field. In the spi"ing generation 

 about 60 per cent, of the flies are females ; in the autumn one the 

 sexes are approximately equal in number. By applying these figures, 

 however unsatisfactory the basis may be, it is believed that 

 entomologists will be better able to appreciate how an outbreak may 

 develop very suddenly, and to predict more accurately the approach 

 of a dangerous infestation. 



GiRARD (P.). Insectes nuisibles aux Arbres Fruitiers et aux Legumes. — 



Vie Agric. et Rur., Paris, xx, no. 9, 4th March 1922, pp. 159-160. 



Porthetria [Bombyx) dispar attacks any non-resinous tree and some- 

 times causes complete defoliation. Banding the trees with packing 

 canvas under which the larvae take shelter for pupation, and under 

 which the adults frequently oviposit, is advocated, or, in cases of 

 severe infestation, spraying with lead arsenate. There are at least 25 

 natural enemies of this moth in France, and these generally reduce its 

 numbers to the normal after a certain time. 



