lo JuLV. 1911-] Tlic Root Borer and its Parasite. 453 



tiee trunk ; and many pass these collars for the purpose of egg-laying, so 

 that the orchardist is depending on something that only stops a percentage 

 of the beetles. 



At Panmure, every tree is " collared " and attended to every morning 

 right through the season, except in the case of gooseberry bushes. As the 

 larvae feed on the roots it makes little difference to them where the eggs are 

 laid, and possibly a gooseberry bush is just as acceptable as an apple tree. 

 It will therefore be seen that the gooseberry bushes require as much pro- 

 tection as the trees. 



Messrs. Moore Brothers, of Vauxhall Gardens, Panmure, have for many 

 years kept a daily account of the number of beetles killed on a 7 -acre 

 patch of their orchard of 60 acres, the only part attacked. During 1905, 

 14,633 beetles were trapped and destroyed. This number diminished until, 

 in 1907, it fell to 7,190 ; in 1909, it increased to 15,360. Not only were 

 these growers extremely careful in trapping the beetles, but greater atten- 

 tion has been given to spraving during the latter years. Still, instead of an 

 appreciable diminution there was an actual increase of over 100 per cent, 

 in the beetles trapped. 



A Parasitical Enemy. 



From my own experience, and that of growers like those referred to, it 

 would appear that there must be .some natural check to the multiplication of 

 this insect in the native timber, otherwise our forests 

 would be entirely depleted. The difficulty the beetle 

 may have in emerging from the soil in the unculti- 

 vated lands would probably to .some extent affect its 

 increase, but not sufficiently to account for the com- 

 paratively little damage that it does to our forest trees. 

 I was therefore led to the conclusion that other factors 

 were at work towards this end, and began investiga- 

 tions in this direction, with the result that a parasite 

 very deadly to the borer was discovercfl. 



On dis.secting a female Leptops in June, i9^o> p^rilitus 1 I'Ptopsi 

 she proved to be full of parasites, .so live beetles were vipkkck d .<» 

 placed in observation cages. In the course of a 



few days j)arasitic larvae emerged from the.se, and pupated in tiny 

 silken cocoons all clustered together, showing at once that they b, longed 

 to the Hymoioptcra (probablv the Bracoiiidce). From these cocoons 

 the perfect in.sect emerged in October, the time of year when the root 

 borers first appear, but unfortunately before being able to obtain more 

 ijeetles the parasites dinl. The parasite was again ob.served in large num- 

 bers during December at Panmure. and January at Mount Cole, near 

 Ararat — tht- onlv places wlu-rc this in.sect has been so far discovt-rt'd. 



'I'he female parasite is furni.shcd with a long <i\ ijiositor. with which 

 sfu' injects her eggs into the abdomen of the beetle. On these hatching, 

 the minute grubs first feed on the eggs of the beetle contained in her body. 

 Sometimes it iiappcns th;it thcsr eggs supplv sufficient fond during the 

 larval rxistencf of th'- |).irasitfs. which can be .seen emerging from their 

 erstwhile habitat ftir the purpose of pui)ating Strange to say. the beetle 

 in .some cases, after tfie exodus of the parasitf. a|)ptars healthv and active 

 for a .short time. As a rule, however, the p.irasiles. after consuming the 

 bfctle's eggs, turn their attention to their host, and « at up aloolutely every- 

 thing contained in her abilomi-n. the licctlc dving as they (Miicrge. 



