CAPE COD CRANBERRY INSECTS 35 



Fall Arnriyworm." 



Tliis insect is not known to Iiave liarnied cranberry vines in Massachusetts. 

 It worked havoc in New Jersey in 1916^- on several bogs bared of their winter 

 water in mid-July. It sometimes injures grasses and grains greatly on Cape 

 Cod and is therefore likely on rare occasions to infest a few bogs there if they 

 iiappen to present favorable conditions when it is prevalent. This species 

 attacks later than the other cranberry cutworms and is the only one, except per- 

 haps the black cutworm, likely ever to infest a Cape bog seriously when the 

 winter flowage is let oflF after July 20. It will not attack a bog drained much 

 iiefore July, this probably explaining why it has appeared as a cranberry pest 

 in New Jersey and not in Massachusetts, for the Cape growers rarely follow 

 the common New Jersey practice of Jiolding the winter water until July to 

 kill out weeds and insects. 



Disfribufion and Food Plants. 



This pest occurs yearly in Central America, Mexico, the West Indies, and 

 South America and its worst outbreaks may originate in those regions. It is 

 evidently a native of tropical or subtropical America. Apparently it cannot 

 survive the winter north of southern Georgia or central Texas. In the years 

 of its great abundance in the South great numbers of the moths fly north- 

 ward, sometimes for hundreds of miles, and lay their eggs. These hatch and 

 the worms develop into moths which again fly northward before laying. In 

 this way the insect in favorable summers spreads over most of the eastern two- 

 thirds of the United States and even to Canada before fall frosts halt it. It 

 sometimes does immense damage to crops throughout this range. Its favorite 

 food plants are grasses such as quack or crab grass, Bermuda grass, blue 

 grass, Johnson grass, etc. It seriously injures alfalfa, clover, corn, cotton, 

 cowpea, kafir, millet, oats, rice, sorghum, sugar cane and wheat. It sometimes 

 attacks beet, bean, buckwheat, cabbage, grape, pecan, pepper, peanut, potato, 

 sweet potato, strawberry, spinach, tobacco, tomato, turnip, and other plants. 



The worms devour each other and other cutworms eagerly. They work 

 rather freely in the daytime, even in sunny weather. 



There usually are five broods a year in the Gulf states, but only one appears 

 in any one place in the North. 



When Oiithreaks mai/ he Expected. 



General invasions of this pest occur nearly always after cold, wet springs. 

 In parts of the Mississippi Valley it is called the "overflow worm," for the 

 farmers attribute its outbreaks to the overflowing of the great river. There 

 is evidence to support this belief. Cold and dampness seem to destroy the 

 insect enemies that ordinarily control the pest but do not harm the worm it- 

 self. This may explain the outbreaks that occur almost yearly in scattered 

 places in the South after periods of heavy local rains. 



Character of Injnri/. 

 The work of this insect is like that of the armyworm (page 33). 



41. Laphygma frugiperda (S. & A.). 



42. Proc. Amer. Cranberry Growers' Assoc. 47, p. 11, 1917. 



