150 MASS. EXPERIMENT STATION BULLETIN 178. 



Character of Injury. 



With the exception of the leaf blades the whole corn plant above ground 

 is subject to the attacks of these voracious caterpillars. 



The larvse after emerging from the egg either commence feeding on the 

 unopened staminate flowers borne by the tassel, or immediately pierce the 

 sheath near its junction with a node. Those which feed on the tassel bore 

 a hole in the side of the buds and feed on the internal succulent parts. 

 Soon these small caterpillars leave the tassel buds and enter the tassel 

 stalks, or terminal internode, where they tunnel through the pith and 

 finally complete their larval life in this internode. These tunnels so 

 weaken the terminal internode that it soon becomes broken over, a t3T)e 

 of injury which is especially noticeable on the early com crop. It is quite 

 evident that this injury indirectly affects the formation of corn on the 

 cob by destroying the pollen necessary for fertilizing the com silk. 



Those larvse which do not feed on the tassel immediately pierce the 

 sheath surrounding an internode, usually where the edges overlap at its 

 junction with a node. Here they feed on the internal surface of the 

 sheath, excavating a groove halfway around the stalk, and then bore 

 directly into the pith where they form long winding tunnels. Whenever 

 the larvse during their tunneling operations reach a node, a rather large 

 cavity is usually formed. From this cavity the larvae sometimes bore 

 through the node, but more often they turn and tunnel in the opposite 

 direction in the originally infested internode. At the termination of the 

 feeding period nearly all of the central portion of the stalk has been eaten, 

 and this so weakens the plant that a strong wind is likely to break over the 

 stalk, thus completing the destruction commenced by the caterpillars. 



A number of these stalk-boring larvse very often attack the small stalk 

 or pedicel bearing the ear, and in some cases may bore directly through 

 this into the developing ear. This injury to the pedicel causes the ear 

 to wither and die. 



The most serious damage to the crop is caused by the large percentage 

 of the second brood larvse which immediately enter the ear after hatching. 

 The injury by this brood to the corn ear is very similar to that caused by 

 the well-known corn ear worm (Chloridea obsoleta Fab.). Besides feeding 

 on the kernels in a similar manner to the corn ear worm, the European 

 corn borer exhibits characteristic tunneling habits and bores through the 

 cob. 



Life History and Habits. 



As the life history has not been thoroughly worked out, it is onlj^ pos- 

 sible to give a brief r6sum6 of it at the present time. 



There are two broods a year of the European corn borer. Hibernation 

 takes place as full grown or nearly full grown larvae, within their tunnels 

 in the corn stalks, and in some cases in the cob. These larvae pupate in 

 the spring and emerge as moths, probably the latter part of May. Soon 

 after emergence the females begin laying eggs on the corn stalks, and in a 



