40 



themseh^es, but also assist the de\elopmcnt of insect pests, are 

 the Chenopodiaceae, especially Chenopodium album, which grows 

 abundantly in potato-fields. Among the pests favoured by it is 

 Pegomyia hyoscyami, Panz. Up to recent years this fly was not 

 abundant enough to infest Chenopodium, its chief food-plant, seriously, 

 but lately it has increased to such an extent as to threaten beet 

 cultivation in some parts of Germany. The chief injury is done to 

 young, four-leaved beet. Should the plants recover from the first attack, 

 they have to undergo a second and again a third. This last is due to 

 the third generation of the fly, which appears so late that the injury 

 in the beet fields is seen in September and October. The eradication 

 of the weed is an obvious remedial measure. If infestation appears 

 on the beet, it becomes a matter of dealing with the first generation 

 of P. hyoscyami by gathering the infested plants, which must be 

 immediately removed from the field and either used as fodder or buried. 

 The plants must not be placed in compost heaps or left uncovered in 

 contact with the ground, as beet withers slowly, and many larvae are 

 thus enabled to pupate in the ground. A simple method of collecting 

 the adults is provided by the raking machine found on farms. The 

 actual rake being lifted out of gear, sacks covered with an adhesive 

 are suspended from the beam bridging the space between the two 

 wheels, and the machine is drawn through the field by a horse. the 

 progress of which disturbs the flies. Even if only a portion of the latter 

 are caught, any decrease in their numbers prior to oviposition will 

 have an effect on infestation. A machine 6 feet wide can easily cover 

 over 18 acres a day. 



Beet cultivation is also seriously affected by the larvae of Blitophaga 

 opaca, L., and B. undata, Miill. The author is inclined to believe that 

 these beetles prefer beet to Chenopodium. Infestation occurs at the 

 same time as the first attack by P. hyoscyami, and is local in character. 

 In infestations of these beetles the field must be left undisturbed until 

 the young autumn shoots no longer show signs of injury. This indicates 

 that the lar\'ac have migrated to the ground in order to pupate. At 

 this time the plants must be gathered, the most vigorous being left 

 standing. If the plants are attacked by both Pegomyia and Blitophaga, 

 which is seldom the case, it is best to wait as if only Blitophaga were 

 concerned. 



In connection with beet pests it is mentioned that Phosphuga 

 atrata, L., cannot be reckoned among them, as has been generally 

 believed. 



Other pests harboured by Chenopodium are Cassida nebulosa, L., 

 and Aphis rumicis, L. The last-named is the most troublesome as no 

 effective measures are applicable against it. 



Krausse (A.). Haufigkeit und Schadlichkeit des Eichenspinners, 



Lasiocampa quercus, L. [The Frequency and Injuriousness of 

 L. quercus.] — Zeitschr. wiss. Insektenbiol., Berlin, xv, no. 7-9, 

 30th April 1920, pp. 190-191. 



In forestry literature Lasiocampa quercus, L., is often mentioned as a 

 pest, but from his own experience and that of others the author 

 considers that the damage done by this moth is slight in character, 

 and though widely distributed in (Germany, it is so rare as to be quite 

 unimportant economically. 



