lo July, 1911-] Tlic Root Borer and its Parasite. 451 



Conclusion, 



If the field or beds have been well established and well cared for, 

 there is every reason to expect that they shall be productive for many years.. 

 A field planted in 1852 is still in existence in California. 



Asparagus canning is a very important industry in America ; and it is 

 now estabfished on a sound cominorcial ba-sis. " Conover's Colossal '" is 

 practically the only variety grown there for that purpose. 



THE ROOT BOREIl AND ITS PARASITE. 



//. ir. Davey, F.E.S., Inspector, Yegetation Diseases \cts. 



The Api)lL' Root Borer {Leptops Hopei) is, in many districts of the 

 State, one of the most formidable enemies of the fruit industry, and has 

 exercised the minds of experts and growers alike in trying to determine ati 

 effective remedy against its ravages. 



The beetles, on emerging from the soil, generally ascend the tree on 

 whose roots they have been feeding during their larval existence. The female., 

 after mating, seeks the leaves on which to deposit her eggs, which vary 

 greatly in number, often reaching as many as 150. The incubation period 

 of the eggs is about three weeks, and the major brood occurs during the 

 spring, but the writer has seen fertile eggs as late as 25th March, and is of 

 opinion that a not inconsiderable number is produced right throughout the 

 year. Not only are the eggs deposited on the leaves of fruit trees, but 

 they have been found on weeds, crops, hedges. &c., so that the beetle has 

 a wide range for the deposit of her eggs. 



The newlv-hatched grub immediately descends and burrows into the 

 ground until it reaches its norm;d haunts among the roots. In spite of 

 trapping the i^eetles and spraying the food plant of this borer with arsenical 

 poi-sons, the menace of this i)articular pest is in no v.ay abated. 



Soils of a heavy stiff nature are eminently suitable to the root borei. 

 owing to the peculiar way in which the larva feeds. It does not bore into 

 the roots of the trees, but rather flutes or grooves them, so that three sides 

 of the tunnel in which the larva has free movement is formed by the root, 

 and the remaining side by the stiff, compact clay. On the other hand, 

 loose sandy soils are unsuital)le owing to the grit continually falling in from 

 the tunnel' walls to the injury of the insert. After becoming full grown, 

 the larva usually retreats to the highest part of its tunnel, where it 

 pupates. In its native haunts, this in.sect is probably kept somewhat in 

 chi'ck li\ ihf difficultv the new ly -emerged and scarc<ly hardened beetle 

 would ha\c in toning its way for some considerable distance through soil 

 cakecl hard .ind unbrok<-u in aii\ \va\ , wlnreas. in the ore-hard, through 

 the amelior.iting iiitlueiue ot cultivation, its path from the depths below is 

 made easy. When we rememl;)er also, tliat, with all insects, the change from 

 the pupa to the imago state is alwavs attended with great risks, it seems to 

 till- wriiii dial th.' rul! ivaii-d soil is a great and unavoidable factor in the 

 increase ot tlie bi-etle. 



As the i)orer only works in stiff soils, it is useless to attempt to suppress 

 the pest bv means of the injection of ])oisonous fumes into the soil, as the 

 clayey nature of the soil would jirevent the fumes from permeating to any 

 considerable ♦■xti-iit !■ xprriinnits carried out. I>v direction ot the Chief 



