225 



has shown that the results obtained do not warrant sucli drastic treat- 

 ment and the necessity of the revision of these laws is therefore 

 -emphasised. 



Intensive cultural methods such as have been successfully adopted 

 in France and Hungary are advocated as an alternative. 



BiTZEMA Bos (J.). De gestreepte Dennenrups {Trachea piniperdd, 

 Pam. = Panolis griseovariegala, Goeze). [The Pine Moth, Panolis 

 jiammea.] — Tijdschr. Planlenziekten, Wageningen, xxvi, nos. 1, 

 2, 4, January, February, April 1920, pp. 28-60, 71-104 & 113- 

 115, 2 plates. 



The abnormal increase of Panolis jlammea, Schiff. {piniperda, Panz.) 

 in Holland in 1919, doubtless due to the warm, dry weather early in 

 1918 and 1919, has led to the publication of this paper, which contains 

 an account of the observations made by the author and others and a 

 review of previous knowledge of this pest in Holland. 



All stages are described and notes on the life-history are given 

 from many sources. It is certain that in years during which the 

 weather has been normal very few individuals are found on pines 

 because P. Jla?nmea is readily affected by unfavourable weather 

 •conditions. The moths do not oviposit indiscriminately on all 

 ■examples of Pinus sylvestris but choose the larger trees that are at 

 •least 20 years old ; in stands of 15-year-old trees injury is unusual. 

 Though P. flatnmea is a pest of Pinus sylvestris the caterpillars also 

 feed on Chamaecy paris laivsoniana and Picea menziesii [sUchensis). 

 It is probable that the caterpillars attack these trees only if the 

 •supply of food on Pinus sylvestris proves insufficient. In view of the 

 conflicting records as to the direction of the compass in which the 

 spread of the caterpillars takes place, it is suggested that it tends to 

 be towards trees that have not been defoUated. It has also been 

 suggested that the mating flight is against the wind, and as the 

 mating usually occurs at a period when east wmds are blowing, this 

 accounts for a second outbreak being eastwards of that of the 

 preceding year. The first signs of defohation become visible at the 

 end of May or early in June. Pupation begins in July and nearly all 

 caterpillars have pupated by August. The adults emerge in March 

 and April. 



As a rule the young caterpillars begin by feeding on the young 

 needles of the May shoots ; if these are not out at the time the larvae 

 hatch, they attack older needles. In serious infestations when the 

 amount of food material is insufficient everything is eaten without 

 distinction. 



It is generally assumed that pines that have been stripped bare 

 must die and should be felled. This is certainly not always the case, 

 and precipitate felling should be avoided. Conifers suffer more than 

 broad-leaved trees, but not all conifers are affected to an equal extent. 

 Picea excelsa dies if defoliated because it is unable to produce new 

 needles in the same year, but Pinus sylvestris does not necessarily 

 succumb, especially if defohation has taken place early in the year. 



The infestation in the various parts of Holland in 1919 is recorded 

 in some detail. 



