58 EXPERIMENT STATION EECORD. 



Since tlie weevil will probably cleave to its native food plant until com- 

 pelled to seek sustenance elsewhere, the author is of the opinion that a whole- 

 sale destruction of the native food plant might invite a quicker than natural 

 adaptation to cotton on the part of this weevil. It is thought that the intro- 

 duction of parasites of the cotton boll weevil w^ould be of considerable assistance 

 in reducing the Arizona weevil and that they would not cause its dispersal. 

 It is pointed out that there is danger of a distribution of weevil-infested buds 

 through the drainage system by summer freshets. Attention is called to the 

 fact that it is of extreme importance that the Thurljeria weevil be kept out of 

 western Texas and any part of the Southeast, since if accidentally introduced 

 into otlier sections it might be able to stand much greater variations of climate 

 than A. grandis and become a much more powerful enemy of cotton. 



Life history of Otiorhynclius ovatus, the strawberry root weevil, under 

 lower Fraser conditions, R. C. Treherne {Proc. Brit. ColumMa Ent. Soc, 

 n. ser., 1912, No. 2, pp. 41-50; ahs. in Rev. Appl. Ent., 1 (1913), 8er. A, No. S, 

 pp. 92-94). — This insect is reported to have caused considerable loss to growers 

 in the lower Fraser Valley and those sections of British Columbia along the 

 Pacific coast where strawberries are grown commercially. It does not appear 

 to attack the crown but feeds on the roots of the plant only, the larva having 

 been found from 6 to 8 in. below the surface. It is said to be far more 

 numerous than is O. sulcatus. 



The incubation period of the egg is about 21 days, the length of the larval 

 stage at least 7 months, and of the pupal stage from 21 to 24 days. The larva 

 is more or less omnivorous, having been taken in clover and timothy grass sod, 

 on wild strawberry from sea level up to an elevation of 500 ft., on the roots 

 of the peach, on rhubarb, Rumex acetosella, Poteniilla glandulosa, Balsamorhiza 

 sagiUata, Poa serotina, and P. pratensis; it has also been found in potato 

 fields, though there is no direct proof of its attacking potato. The larvae 

 attack the plant roots by making longitudinal slits in portions of the epidermis, 

 subsequently girdling the roots either directly or in a spiral manner. The most 

 serious injury is done in early spring when the larvae are nearly full grown and 

 attack the main roots, which are sometimes cut off 2 in. or so from the crown. 



The pupal stage is passed at from 4 to 6 in. or even 8 in. below the surface. 

 The female deposits some 50 eggs within a period of 4 to 5 days; this period 

 may be extended to as long as 15 days. Oviposition takes place from the end 

 of June to the end of August, varying somewhat according to the season. 



Strawberries grown on the matted row system are not as a rule seriously 

 affected the first year after planting, unless the soil was previously infested 

 by the insect. The injury is noticeable the third summer, often reducing the 

 crop fully 50 crates to the acre. 



The following remedial measures are suggested : The growth of strong varie- 

 ties; the running of chickens over the grounds; trapping the adult weevils under 

 boards (only useful to small growers) ; the use of some sticky material as traps; 

 spraying with arsenate of lead (only useful after the first crop is harvested 

 and when the weevils are very numerous). ; chemicnl remedies, potassium cyanid 

 and carbon bisulphid. but the author is doubtful whether any remedy of this 

 kind can be used to kill the eggs, larvjie, or adults which will not at the same 

 time destroy the plant ; burning the plants immediately after the first crop has 

 been gathered by covering them with dry straw and setting fire to it; plowing 

 at the end of July or at the beginning of August, with frequent cultivation 

 previous to or during the winter; autumn planting; plant renewal during the 

 middle of the second summer; and 1-year crops instead of 2-year crops, though 

 this is not satisfactory. Rotation of crops is strongly advocated in the follow- 

 ing order, derived from local experience — strawberries, potatoes, and rhubarb. 



