INSECT PESTS AND THEIR PARASITES.

Otago Witness, Issue 2808, 8 January 1908, Page 10

INSECT PESTS AND THEIR PARASITES.

Mr W. a. Froggatt, F.L.S., of Victoria, who ie travelling in the interests of the Agricultural Department of that State, recently paid a visit to the orchards in California and other parts of the. United I States. From a progress report which ■ appears in the Victorian Journal of Agri- , culture it seems Mr Froggatt is eomewnat i sceptical as to the efficacy of the so-called natural enemy of orchard pests. Writing of his visit to Pijari Valley, between Monteroy and Vera Cruz, where* some 14^,000 , acres are under orchard, Mr Froggafct states that the .oodlin moth is .very variable in. its attacks. Spraying is universal, the growers spraying with arsenite of lead from three to fivo times in the season. No bandages are used where systematic spraying is carried on, but in many places' the trunks t of the apple- trees , were bound round with/ roap soaked in etiokfast, to prevent the tent moth caterpillars getting up ./into the trees,' aa the*' tent moth, unlike the tussock moth caterpillars, cannot b© killed with arsenical sprays. • Where spraying ia not carried out' the codlin moth is just, as bad as in Australia.* In this valley a number of the codlin x moth parasites (Ephialtes oarbonariua) were "turned out over a year ago, but noneof the residents have ever seen them since. And I might state that I have been unable to find one instance in which this ichneumon parasite has been fouifil in an orohard. Mr Isaac (commissioner ai Sacramento) said he found two in his garden a 'few weeks before, where a. great number had been t.urned out in tan infested apple tree, but I oould find no" trace of them, though oodlihi xnoth grubs- were very plentiful. I asked all the officers of the State Horticultural Department if they could send me into an orohard where I could see this parasite ■working under natural conditions, but they did not know of any. The general opinion 1 of all the apple-growers with whom I talkedi is that this parasite is a failure up to tEer present time in California. After having" visited a number of other fruit-growing" districts, Mr Froggatt writes: — "The observations made durinar niv three weeks' investigation • amonsr the insect pests of the orchards as to the value of parasites and) the opinions of the' leading men interested in the industry, all point to the same conclusions — namely, that in spite of the money and work that have been expended duringthe last 20 years in 'the State of California upon the introduction and propagation *ol foreign parasitic insects to destroy scale and other injurious insects,, with on© or two exceptions they have very little commercial value, -for unless they are effective «nough to render tKe work of spraying and fumigation unnecessary they minrhfc as well not exist." In concluding his report Mr Froprsratt" says:— "The codlin moth parasite, as previously pointed out, in spite of Mr Compere's accounts of its work," andi E&e offer of a colony by the State Board of ifortlculture to several of our States for £\ 000 each, • has done nothing outside the office insectarium."