441 



the proposal to introduce another ant, Prenolepis fulva, as a means of 

 controUing this insect [see this Review, Ser. A, v, p. 235]. 



De Bessenbladwesp, Pteronus rihesii, Scop. (Nematus veniricosus, Latr.) 

 [The Currant and Gooseberry Sawfly.] — Instituut v. Phytopato- 

 logie, Wageningen, Vlugschrift no. 17, May 1917, 6 pp. 



Energetic measures against the first generation of Pteronus ribesii, 

 Scop., will limit the damage done by the second. In warm summers 

 a third generation of this sawfly occurs, which is the least harmful, 

 but needs control on account of the infestation it gives rise to in the 

 following year. The best remedy is spraying with 0'5% lead arsenate 

 or 1% Paris green in Bordeaux mixture, millc of lime, or water. As 

 samples of Paris green are often entirely free from arsenic, Urania 

 green is recommended in place of it. A solution containing about 

 i\) oz. of American or Persian insect powder in If pints of water may 

 be used, or the bushes may be dusted with either of these powders. 

 Lime or tobacco may also be used for dusting and quassia-soap 

 solution for spraying. On a small scale it is possible to use cold water 

 alone ; for if the spray is sufficiently powerful, it will cause the larvae 

 to drop to the ground, where they may be collected on sheets, etc., 

 while if the ground has been heated by the sun many will die on that 

 account. 



Cheimatobia hrumata and Abraxas grossulariata may be controlled 

 by spraying with Q-^^o carbolineum, C. brumata, being also checked 

 by banding. 



PaTZEMA Bos (J.). Het Stengelaaltje {Tylenclms devastatrioc) en de 

 tegenwoordig in de Bloembollenstreek heerschende aaltjesziekte 

 der Narcissen. I. [Tylenchus devastatrix and the Eelworm Disease 

 of Narcissi now occurring in the Flower-bulb District.] — Tijdschr. 

 PlantenzieJden, Wageningen, xxiii, no. 3, June 1917, pp. 99-135. 



Of late years a disease of narcissi has broken out in the Dutch bulb 

 district with such violence as to be a serious menace to their 

 cultivation. Tylenchus devastatrix (bulb eelworm) causes this disease, 

 which is far more serious than the disease in hyacinths due to the 

 same Nematode. The appointment in April 1917 of a Government 

 investigator seemed a fit opportunity for recording the author's 

 observations. This first part- of the paper deals with T. devastatrix 

 in general. This Nematode is able to live and multiply in a very 

 large number of plants, but tends to adapt itself to particular species ; 

 under certain circumstances, it can remain without feeding or showing 

 signs of life while retaining the faculty of becoming active again under 

 more favourable conditions. A list of 68 food-plants is given, and 

 this is believed to be incomplete. Though some plants are more 

 susceptible to attack than others, it is generally the case that this 

 Nematode has a marked preference for the plant in which it has lived 

 for generations. This is of great practical importance and explains 

 why peas and garden beans are almost uninjured in infested ground 

 where rye and oats always suffer. In some districts where T. devastatrix 

 lives in red clover or lucerne, other plants are not much attacked, and 

 this explains why Havenstein and Kiihn supposed the clover eelworm 



