208 



• 



Ploughing the wheat stubble under is an effective remedy [see 

 also R.A.E., A, v, 213]. This would necessitate a change in the 

 existing rotation of crops where wheat is used as a nurse crop for 

 clover, but it would seem advisable to adopt it if large sums could be 

 saved annually by this means. It would also control Hessian fly 

 {Mayetiola destructor), and all the grain joint- worms could be controlled 

 in this way if necessary. The wheat-straw worm {H. grandis) may be 

 controlled by leaving 40 yards clear between new wheat and infested 

 stubble, as the wingless generation cannot cross the interval [R.A.E., 

 A, viii, 76]. 



If necessary, the insects attacking cultivated grasses could be con- 

 trolled by clipping the fields in spring in order to delay the appearance 

 of seed stalks so that the insects would have nowhere to deposit their 

 eggs. 



Frank (A.). Disease and Insect Troubles of Raspberries and tlieir 

 Control. — Mthly. Bull. Washington Agric. Expt. Sta., Pullman, 

 vii, no. 11, February 1920, pp. 188-192, 6 figs. 



Some of the common insect pests of raspberries have become 

 eatabhshed in western Washington, and growers are asked to do every- 

 thing possible to prevent their spread. They include the raspberry-cane 

 maggot [Phorbia rubivora], which oviposits near the tips of the new 

 shoots, and the grubs of which enter the pith of the cane, bore down a 

 few inches and then turn outwards to just beneath the bark and girdle 

 the twig. This causes wilting and the formation of a bluish ring where 

 the girdling occurs. When mature, the maggot bores down through 

 the pith and enters the ground, where it pupates, emerging as an 

 adult fly the following spring. All wilted shoots should be cut off 

 several inches below the girdling and burnt. 



The raspberry and blackberry root or crown borer, Pennisetia 

 (Bembecia) marginata, tunnels in the canes, crowns and roots of rasp- 

 berries and blackberries. The eggs are laid on the underside of the 

 leaves from late July until early September. The young larvae crawl 

 down a cane to the ground surface and enter the cane where they 

 hibernate. The next summer they again bore in the crown and cane, 

 becoming inactive in the autumn, and in the following spring they bore 

 upward through the cane, make a hole to the outside, pupate, and the 

 moths emerge leaving the pupal case wedged in the emergence hole. 

 The only practical remedy is to dig out and burn aft'ected plants. 

 Birds and chickens will eat many of the moths. 



The red spider, Bryobia pretiosa (pratensis), lays masses of dark red 

 eggs on canes in the winter. During summer the mites feed on the 

 underside of the leaves and spin small webs there, the leaves becoming 

 spotted with yellow or turning reddish-brown. A spray of powdered 

 sulphur or of sulphur in water will kill many of them. The strawberry 

 root weevil, Otiorrliynchus ovatus, frequently attacks the small roots 

 of raspberry canes, but does not constitute a serious pest. The rasp- 

 berry cane borer, Oberea bimaculata, girdles new shoots by making two 

 rings of punctures and laying eggs in the cane between them. The 

 tip of the shoot withers. The grub of this Longicorn bores its way 

 down the cane, taking until the autumn of the second season to reach 

 the ground, and forming a gall or swollen ring on the cane. The wilted 



