189 



A system of fumigation under vacuum is described and illustrated. 

 By this method dates in any form , can be freed from infestation 

 by one hour's treatment, and it is considered inevitable that this 

 system will ultimately be adopted for many kinds of food products. 

 At present lack of equipment has limited experiments to only a few 

 of the possibilities, but insects that have been successfully "treated 

 include Phthorimaea opcrciilella, Z. (potato- tuber moth) in potatoes, 

 insects infesting dehydrated vegetables (which will in future be treated 

 by this method as a regular trade practice), and Merodon equestris 

 (narcissus fly) in bulbs, etc. These" promising results have led to 

 further investigation of this method in the use of liquid insecticides. 

 An application was made with date offshoots for the control of 

 Phoenkococcus marlatti ; these were submerged in the insecticide and 

 the air exhausted ; all air pockets are expanded, and the air rises to 

 the surface in bubbles. As the desired vacuum is obtained, the 

 pressure is released and the insecticide penetrates into all interstices 

 of the plant. The time required is fifteen minutes, and growers 

 report complete destruction of the scale and no injury to the 

 offshoots. The exact procedure for certain Diaspine scales on nursery 

 stock has yet to be worked out. 



For the destruction of Pseudococciis gahani (citrophilus mealvbug) 

 in empty fruit-boxes a box steriliser has been devised which is automatic 

 in action and is attached to the box dump with which it works, 

 passing the boxes through a hot chamber at a temperature 

 of 200° F. ; this kihs all forms of the scale. Steam has been used as 

 the killing agent, but it is hoped to develop a steriliser using hot air, 

 in which the entire apparatus will be complete in itself, with its own 

 heating unit. The difficulty of applying prompt remedies for grass- 

 hopper invasions has always been that poison bait has had to be freshly 

 prepared to be effective ; a formula has now been devised that can be 

 prepared beforehand and preserved in cans for use when needed. 



Urbahns (T. D.) . Report of Field Entomologist (Sacramento) 1919-20. 



—Mthly. Bull. Cal. Dept. Agric. Sacramento, ix, no. 10-11, 

 October-November 1920, pp. 435-439, 2 figs. [Received 10th 

 February 1921.] 



The introduction of parasites into California has chiefly been effectual 

 from South Africa, with the object of reducing the black'scale [Saissetia 

 oleae, Bern.]. The distribution of Coccinellids has continued on a 

 large scale, and there is urgent demand for Hippodamia convergens 

 to check the development of Aphids. 



Field control of insects has included efforts to prevent the recurrence 

 of the enormous loss occasioned annuallv by pears infested with 

 codling moth [Cydia pomonella]. Promising 'results were obtained 

 from thorough spraying, but there are still certain defects in this 

 system to be studied. Against grasshoppers, at least 350 tons of 

 poisoned bait have been distributed annuallv for the past two seasons. 

 Tortrix {Ar chips) argyrospila and T. [A) rosaceana (leaf-rollers) 

 have caused great injury to prune and pear trees. Arsenical spravs 

 were of considerable value, but the project must be carried through 

 the winter for a comparison of winter sprays against the eggs of these 

 moths. Remedial measures against Crioceris asparagi, L. (asparagus 

 beetle) have shown promise, but require further studv ; the results 

 of spraying for Tacnioiiiyips inconsequens {pyri) (pear 'thrips) proved 



