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APPLE MAGGOT FLIES Aid THE I'lfEATSE R 



At a recent nieeting of pest control specialists from tiie i-levf England states and 

 the Hudson Valley of New Yorkj it v/as reported almost unanimously that apple maggot 

 flies iirere active much later than usual and generally that the infestation ty this 

 pest increased over that of last year throughout New I'iigland, The Hudson Valley with 

 much less precipitation and higher temperature did not have a noticeable increase. 

 This increase was very noticeable in Massachusetts where flies vrere often seen in raid- 

 October during the harvest of the late varieties of apples. 



In spite of this, the specialists reported that emergence of flies from cat^es 

 was about normal. In our cages at Waltham the greatest emergence occurred het-Jven 

 July 17 and 26 v\rith the actual maximum on Jvly 23 and the last emergence on august I'ip 

 Therefore we cannot correlate the late activity with any actual recordsof late emer- 

 gence. 



The most logical explanation is that cool wet weather favored a long life for 

 the flies, some of which lived for about 2-1/2 months. The length of life of the 

 flies has never been accurately determined because they do not act normally in cap- 

 tivity. It has been noted, hov/ever, that the flies live longer in late summer and 

 early f all than in the hot weather of July, In the orchards these late flies are 

 principally migrants and the longer that they live, the more they can migrate. 



In general, the control of "railroad worm" flies in well sprayed commercial or- 

 chards was good in 195it, and the recOTtaaended materials and combinations were effective 

 v/hen applied thoroughly and timely, lifhere infestations developed, they could be traced 

 to loss of insecticide residue from heavy rains, especially on August 9-10 and in the 

 Carol and Edna hiirricanes. Nearby unspiayed trees were a more serious source of mi- 

 grant flies this year because the flies lived longer and travelled farther. 



i 



Much interest has been shown in soil treatments to control the population of 

 apple magpot flies in hopes that such treatments can be used uiider a feiv-trees or in 

 apple dumps ivhere large numbers of apple maggots have accumulated. In our recent ex- 

 periments none of the insecticides used prevented fly emergence to a high degree con>- 

 pared to the check, Hovrever, soil treatments with dieldrin and heptachlor killed 

 9^% or more of the flies witliin a few hours after they emerged. This proved that the 

 insects are affected by contact vdth the insecticide as they burrowed upward through 

 the soil in the adult or fly stage rather than by contact as larvae or pupae. In 

 these experiments the only ineffective insecticides used as soil treatments were the 

 organic phosphates, particularly malathion emvilsion, 



— I'll ,D,'.<hitcomb 

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Publication Approved George J, Cronin, State Purchasing Agent - ^'19 



