190 



disappointing, partly, perhaps, owing to unfavourable weather condi- 

 tions ; more thorough and effective spraying methods are necessary. 

 Red spider [Tctranychus] has been one of the most destructive pests of 

 the season ; and an educational campaign against it is advised. 

 Pseudococcus maritimus (pear mealybug) is becoming increasingly 

 abundant, and more attention should be given to remedial measures 

 for it. TypopJwrus canellus (strawberry leaf beetle) is a dangerous 

 pest, and its control requires careful consideration. 



Armit.\ge (H. M.). Report of the Biological Control Work directed 

 against the Mealybugs, 1919-20.— 3/////)'. Bull. Cal. Dcpt. Agric, 

 Sacramento, ix, no. 10-11, October-November 1920, pp. 441-451, 

 7 figs. [Received 10th February 1921.] 



Much progress has been made in the biological control of the 

 mealybugs infesting Citrus in southern California. To place this work 

 on a sound economic basis it will, however, be necessary to find a 

 cheaper food-plant than potato sprouts on which to rear the mealybugs 

 for maintaining a supply of parasites. The species against which the 

 parasites are used are Pseudococcus gahani, P. citri, P. maritimus 

 and P. krauhniae. Particulars of the production of parasites in the 

 laboratory during the past three fiscal years, as well as for July and 

 August of 1920, are given, the species reared or collected including 

 Cryptolaemus montrouzieri, Tanaomastix abnormis, Leucopis bella, 

 Sympherohiiis sp., Rhizohius ventralis, R. lophantae, Hyperaspis 

 lateralis, Novius cardinalis, Panridia peregrina, Orcus chalybaeus and 

 Delphastus sp. 



A few of the outstanding results of the year's field work include the 

 commercial control of P. citri in Ventura county ; the establish- 

 ment of the internal parasites, T. abnormis, Gir., and P. peregrina, 

 Timb., on Pseudococcus krauhniae (Japanese mealybug) ; the com- 

 mercial control of P. gahani in one locality by C. montrouzieri ; and the 

 complete clearing of P. maritimus b}^ the same predator in another 

 locality and of P. citri in a part of Orange count}-. Sympherobi-us 

 barber i (brown lacewing), liberated from laboratory-grown material, 

 has been a prominent factor in reducing the numbers of P. krauhniae, 

 and T. abnormis was established on several new infestations of 

 its host, P. citri. Considerable numbers of mealybugs have also been 

 destroyed by the native predators, Chrysopa sp. (green lacewings), 

 the Dipteron, Leucopis bella (which clears up egg-masses of P. gahani), 

 and the brown-lacewings, S. barberi and S. californicus. Regarding the 

 relation of ants to the biological control of mealybugs, the author 

 considers that they are a considerable hindrance, and as a rule ant 

 control is demanded of the grower before he is supplied with natural 

 enemies. Further increase in production is necessary if the demands 

 upon the laboratory are to be met. The working of the various 

 insectaries is described. 



Compere (H.) . Report on the Biological Control Work directed against 

 the Black Scale, 1919-20.-^1/////)'. Bull. Cal. Dept. Agric, 

 Sacramento, i.x, no. 10-11, October-November 1920, pp. 

 451-458, 2 figs. [Received 10th February 1921.] 



This report includes a discussion of the fundamental principles 

 governing natural control of black scale [Saissetia oleae], and an account 

 of the laboratory work and insectary production. The parasite 



