453 



dusting, if properly done, should be almost, if not quite, as satisfactory 

 as spraying. Acrohasis hehescella has been much less important than 

 in 1916, owing to the large degree of parasitism and in part also to 

 summer sprayings. Hijphantria cmiea (fall web-worm), which caused 

 severe damage in 1916, has been studied. There are e\'idently two 

 complete generations and a partial third one annually, some of the 

 second brood failing to emerge the first year and hibernating as pupae, 

 as do all of the third brood. Proteoptert/x deludmia (bud worm) has 

 been studied in the laboratory. There are several generations of this 

 moth in a year ; the first generation pupates under loose bark on the 

 trunks of the trees, while later generations use folded leaves in which 

 to pupate. It seems probable that the first brood might easily be 

 trapped under bands placed round the trunks. 



Nezara viridala (green soldier bug), which was a serious pest in 

 1916, has been reduced almost to a minimum, probably owing to 

 natural parasites. It seems evident that the disease known as kernel 

 spot is either caused directly by these bugs or carried by them [see 

 this Review, Ser. A, vi, p. 433]. 



The sweet potato root weevil [Cylas formicarius] has recently 

 been found in one locality in Georgia. Instructions for control were 

 at once sent to the infested districts and it is hoped that it may be 

 exterminated before the infestation has spread. 



Beal (F. E. L.). Food Habits of the Swallows : A Family of Valuable 

 Native Birds. — U.S. Dept. Agric, Washington, D.C., Bull. no. 619, 

 8th March 1918, 28 pp., 2 plates. [Received 20th August 1918.] 



This bulletin records the usefulness of various species of swallows 

 in insect control, and gives lists of the insects preyed upon by each 

 species. 



McCltntock (J. A.). True Nature of Spinach-Blight and Relation of 

 Insects to its Transmission.— Ji. Agric. Research, Washington, D.C., 

 xiv, no. 1, 1st July 1918, pp. 1-59, 12 plates. 



It has been observed for some years past that spinach-blight, 

 which is the cause of the greatest aimual loss to growers in eastern 

 Virginia, became most serious within a short time after Aphids were 

 observed to be abundant on the plants. Spinach i$, grown in autumn, 

 winter and early spring, during which period Macros iphum solanifolii, 

 Ashm. (potato aphis) and Myzus (Rhopalosiphum) persicae, Sulzer 

 (spinach aphis) are the most abundant insects on the plants. 



M. solanifolii, owing to its habits, has proved to be the more 

 important agent in the dissemination of the disease. Experiments 

 showed that direct transfers of virus-bearing Aphids to healthy 

 plants produced infections of spinach-blight ; inoculation with the 

 juice of crushed infected Aphids also produced infection. Transfers 

 of Aphids that had not previously fed on diseased material produced 

 blight infection in a few cases. Virus-bearing Aphids produced 

 infections in healthy plants when allowed to feed on them for two 

 minutes. The infectivity is proved to be greater with adult Aphids 

 than with those that are immature, and the incubation period of 

 the disease produced by the adults is materially less than when the 

 disease is produced by immature forms. Aphids are capable of 



