l66 MAINE AGRICULTURAL EXPERIMENT STATION. I916. 



Sweet (Map, T9) 88 per cent; Munson Sweet (Map, U2) 99 

 per cent in 1914, and 98 per cent in 1915; Transcendent crab 

 (Map, K2) 80 per cent and Benoni (Map, L) 88 per cent on 

 August 19. 



It is reasonable to suppose that when badly infested early 

 varieties are harvested, such as the Transcendent crab and Mun- 

 son Sweet, that the absence of apples on the trees will cause 

 the female flies to seek other fruit in which to oviposit. The 

 Transcendent crabs and the Munson Sweets were harvested by 

 the middle of September. It must be noted thiat the last appli- 

 cation of the spray in the orchards and residential district were 

 made between August 12 and 22, during the two seasons. The 

 bait was washed off by rains before the early varieties had 

 been harvested, leaving the fruit trees unprotected, at the time 

 when the disipersal of the flies probably occurs. 



CONCLUSIONS. 



In 1914, no conclusions could be drawn on the effectiveness of 

 the poisoned bait spray from any of the experiments that we 

 performed, due to the fact that the different soluble poisons 

 scorched the leaves and therefore insoluble arsenicals were 

 substituted in the later treatments. A series of experiments 

 with different amounts of soluble poisons, such as potassium 

 and sodium arsenate and sodium arsenite, show that as small a 

 quantity as one-quarter of an ounce of these insecticides dis- 

 solved in boiling water and then added to three gallons of water 

 with one pint of molasses will burn the foliage of the apple 

 trees. 



In 1915, during a very rainy season, the results obtained 

 with three applications of the poisoned bait spray containing a 

 soluble poison dissolved in diluted molasses, showed that the 

 infestation varied from o to 20 per cent in orchards situated 

 away from the margin of the experimental area, and from 32 

 to 57 per cent in orchards near untreated trees. An even dis- 

 tribution of the droplets over the foliage is more effective than 

 spraying the trunk, large limbs and foliage of the lower 

 branches. The number of applications necessary tO' insure good 

 results can not be stated with this work still in its experimental 

 stage. In orchards where tent-caterpillars have practically 

 stripped or partially defoliated the trees the poisoned bait with 



