(larval infestation in the fruit was reduced by 90'o). For direct 

 fly control, this method of capturing the flies with sticky yellow 

 traps is laborious and doubtless uneconomical on a large scale. 

 But it does illustrate the effectiveness of the traps. 



Studies originated by Dr. Ralph Dean in the Hudson Valley in 

 the 1930's and Dr. A.C. Hodson in Minnesota in the 1940's showed 

 that apple maggot flies are attracted to the odor of decomposing 

 protein and the odor of ammonia. The real reason for this attrac- 

 tion isn't known for certain. But it is known that the insect hon- 

 eydew on which the flies feed does contain amino acids (the build- 

 ing blocks of protein) . It seems quite likely that as honeydew 

 ages, it decomposes slightly, and in the process gives off ammonia 

 (which is a product of protein putrefaction). Hence, the flies 

 may be cueing in on ammonia as a guide to locating honeydew. 



Ammonia-type substances and protein hydrolysates have now been 

 added to the sticky-coated daylight fluorescent yellow rectangles 

 to combine in one trap the essential visual and olfactory stimuli 

 eliciting the food-finding behavior of the flies. Currently, Zoecon 

 Corporation (c/o Dr. W.H. Palmer, 346 South Avenue, Williamson, N.Y. 

 14589) is marketing this type of trap. It is a Saturn Yellow* 9" x 

 10" cardboard rectangle. One surface of the rectangle is coated 

 with Bird Tanglefoot*, with protein hydrolysate and ammonium acetate 

 mixed into the Tanglefoot. For transport and handling the card is 

 folded in half, with the Tanglefoot area inside. The trap is easily 

 assembled for use by folding back the cardboard to expose the Tangle- 

 foot, and attaching a wire for hanging it in an apple tree. 



Every grower knows from past experience which of his blocks 

 are in greatest danger from maggot attack. Employment of 1-2 traps 

 per acre in maggot hot-spots would provide instant information on 

 the status of the maggot fly population. This will aid in better 

 timing of maggot sprays, and avoidence of unnecessary applications 

 when no maggots are present. 



In the next two issues of Fruit Notes , I will discuss other as- 

 pects of apple maggot fly behavior which have practical import. 



COLLECTING SOIL SAMPLES FOR NEMATODE IDENTIFICATION 



R.A. Rohde 

 Department of Plant Pathology 



The plant-parasitic nematodes that attack fruit trees live in 

 the soil and feed on the roots. They are too small to be seen un- 

 less removed from the soil. Nematode populations vary greatly both 



