REACTIONS TO CHEMICAL STIMULI 157 



dates of application of spraying. Temperature affected the 

 efficacy of the measure, since the majority of the insects responded 

 while the mean thermometer reading was 70° F. or above. A 

 sudden fall in temperature will practically stop all moths visiting 

 the baited traps. His conclusion is that a sufficiently attractive 

 lure may be discovered which will destroy a large enough number 

 of moths at a cost that may recommend its adoption as a supple- 

 mentary control measure. Fowler (1927) carried out very similar 

 experiments in South Australia, using fermented apple juice, 

 with and without the addition of 10 per cent, by weight of sugar^ 

 and a solution of molasses to which a small amount of yeast 

 powder had been added. On the whole it was found that apple 

 juice proved the more attractive of the three mixtures. He 

 concludes that it would probably be profitable to maintain traps 

 during the maximum emergence periods of the insect rather than 

 for the whole flight season. Their greatest value lies in their 

 use in determining dates of maximum emergence, so as to make it 

 possible to fix the most advantageous times for spraying. 



The control of the Oriental Peach Moth by chemotropic means 

 has been the subject of experiments by Peterson (1925), who found 

 that large mmibers of this insect responded to a molasses-yeast 

 mixture. He later (1927) tested about 250 aromatic chemicals 

 as possible attractants, but several fermenting sugar-producing 

 substances proved the most efficient. Fermenting fruits (dried 

 fruit in water) were also found to attract large numbers of the 

 moth. Several other investigators have found that the insect 

 responds readily to suitable chemical stimuli : Frost (1928) 

 believes that chemotropic methods may find a definite place in 

 the control of this insect, notwithstanding the fact that the 

 incidence of prolonged low temperatures or high precipitation 

 exercises an adverse influence upon their efficacy. The inexpen- 

 siveness of the method, the simplicity of the apparatus (pails only 

 being used) and the small amount of labour required, all point in 

 its favour. Stear (1928), on the other hand, using a 10 per cent, 

 solution of molasses in water, arrived at an opposite opinion. He 

 states that two years' experiments failed to give appreciable con- 

 trol. By marking moths and releasing them, and noting the 



