THE EUROPEAN CORN BORER. 149 



vicinity, oviposition took place and the European corn borer became 

 established. 



Early sweet corn gro\\'Ti in market gardens 10 to 12 miles inland has 

 been seriously attacked by this pest for the past three or four years, and 

 from this we might infer that it was imported about 1910. 



A survey of eastern Massachusetts showed that some towns located at 

 the mouth of the Mystic River were more generally infested than others. 

 At the mouth of this river is located the Charlestown Navy Yard, which 

 probably has one of the largest "rope walks" in Eastern United States. 

 Whether the European corn borer was first introduced at the Navy Yard, 

 or at some cordage company located on the opposite bank of the river, it 

 has been impossible to ascertain, but enough has been written to show 

 that it probably was first estabUshed in this vicinity. 



Present Distribvtion. 

 The area infested by the European corn borer in Massachusetts is 

 approximately 100 square miles in extent, and is located immediately 

 north and northwest of the city of Boston. The places most severely 

 infested during the past season were Somerville, Medford, Maiden, Everett, 

 Chelsea, Revere, Lynn, Saugus, Melrose, Stoneham, Winchester, Arling- 

 ton, Belmont, Cambridge, Brookline and the following parts of Boston: 

 South Boston, Brighton, Roxbury and Dorchester. 



Food Plants. 



At the present time sweet corn is the only valuable commercial crop 

 seriously attacked by this pest, for the other food plants — hops, hemp 

 and millet ■ — are not grown within the infested region of Massachusetts. 

 The most commonly infested weeds and grasses are barnyard grass 

 {Echinochha crus-galli Beauv.), pigweed {Amaranthus retrojlexus L.) and 

 foxtail grass {Setaria glauca Beauv.). Dahlia stems are also injured by the 

 European corn borer. The moths apparently prefer to oviposit on corn, 

 and will not infest weeds and grasses unless corn plants are not available 

 in sufficient numbers. 



Importajice. 



Sweet corn is practically the only corn grown within the infested area, 

 and the amount of damage caused by the European corn borer depends 

 upon whether it is an early or late variety. The early crop of sweet corn 

 is picked during late July and early August, and by reference to the life 

 history it will be seen that these plants are subjected to the attack of the 

 first brood of larvae only. The late corn, however, suffers from the attack 

 of both the first and second broods of larva?. While the early crop may 

 be damaged to the extent of 10 to 20 per cent., the loss to late corn plant- 

 ings may be as high as 75 to 80 per cent. This higher percentage of 

 damage to late corn is caused by the habit of the small second brood 

 larvae of boring through the husk and tunneling in the developing ear, 

 making it worthless for market. 



