REPORT OF CRANBERRY SUBSTATION FOR 1916. 227 



As a treatment for the second brood, it may have to compete with arsenate 

 of lead, for there is danger of injuring tender foliage, and especially blos- 

 soms, in spraying with any contact insecticide, and arsenate of lead is far 

 more effective with the second brood than with the fii'st. Proper treatment 

 of the first brood with "Black-Leaf 40" may check the pest so well that 

 a thorough treatment of the second brood will not be so necessary as it is 

 at present. In anj^ case, not more than one application of "Black- Leaf 

 40" for the second brood is likely to be desirable. 



The writer gave some cranberry uprights sprayed with "Black-Leaf 40" 

 to some gypsy-moth caterpillars, providing another lot with unspraj^ed 

 vines as a check. The latter were eaten much more freely than the former. 

 This suggests that the effectiveness of this insecticide may be partly due 

 to a deterrent property. 



The second brood of the fireworm did less damage than usual this sea- 

 son, and less than might have been expected from the abundance of the 

 first brood. The wet season seemed to check it strongly somehow. 



The Cranberry Fruit Worm {Mineola vaccinii (Riley)). 



This insect did the least injury this season of any year in the wTiter's 

 experience. ' It has not been less prevalent since 1903. We have no relia- 

 ble information concerning its abundance in years previous to 1904. 



The writer has tried to determine, as far as possible, the relative abun- 

 dance of this pest in the various cranberry-growing regions. It is most 

 harmful on Cape Cod and in Wisconsin, being far less troublesome in 

 New Jersey, the amount of injury on dry bogs (without -winter-flowage) 

 in the latter section, when the writer was there in 1915, being about the 

 same as that on the flowed bogs of the Cape in the same season. It does 

 about the same damage on Long Island and Nantucket as in New Jersey, 

 being far less prevalent there than on Cape Cod. It appears to be almost 

 if not entirely, unknown on the Pacific coast of Oregon and Washington. 



It will be seen that this insect is not usually very troublesome except in 

 the regions with comparatively cold and dry climates, a heavier total precipi- 

 tation as well as a higher average temperature being characteristic of the 

 warmer sections. One might expect from this that any variation in the Cape 

 Cod climate toward that of the warmer regions would be likely to tend to 

 reduce the pest, whereas any variation in the opposite direction woidd be 

 likely to tend to make it more abundant. 



Cape Cod Data appear to strongly substantiate this Conclusion. — The 

 season of 1905 was the worst on record for fruit-worm injury. The Cape 

 had a lower mean temperature in 1904 than in any subsequent year up to 

 the present time, and in 1905 had a smaller total precipitation than in any 

 year since, in spite of the fact that the rainfall in all the last five months 

 of the j^ear except October was heavy. Of the severity of the winters 

 1903-€4 and 1904-05, the Annual Summary of the New England Section 

 of the Climate and Crop Service of the Weather Bureau for 1905 (page 3) 

 remarks as follows: — 



