90 DEPARTMENT OF AGRICULTURE. [Pub. Doc. 



Insects of the Year 1918. 



Insect conditions appear to be closely correlated with weather 

 conditions in many cases. The severe winter of 1917-18 

 apparently had considerable effect on the San Jose scale 

 (Asjndiotus perniciosus Comst.), destroying more than the usual 

 number of these insects and so checking them that few com- 

 plaints of their injury were received last summer. The parasite 

 of this insect (ProsjMltella perniciosi Tower), first discovered 

 at Amherst, and which for a time killed up to 90 per cent 

 of the scales in some places, has become less effective, and as 

 the other parasites do not appear to have increased in abun- 

 dance, the decreased importance of the scale this past season 

 can in all probability be considered as due at least largely to 

 the winter. 



The most serious feature of the insect situation in Massa- 

 chusetts during 1918 is probably the continued activity and 

 spread of the European corn borer (Pyrausta 7iubilalis Hbn.). 

 This insect was discovered in the fall of 1917 in many places 

 near Boston, tunneling in corn and other plants. It is widely 

 distributed in Europe, where it feeds on corn, hops, hemp, 

 millet and several kinds of grasses, and if it should spread to 

 the "corn belt" in the United States would undoubtedly 

 cause enormous loss. 



The European corn borer is now present over more than 135 

 square miles of territory, mainly west and north of Boston. 

 Numerous reports of its presence elsewhere in the State have 

 been investigated, but the trouble in every case thus far has 

 been due to the common stalk borer (Papaipema nitela Guen.). 

 Sweet corn is practically the only kind of corn grown within 

 the area thus far infested, but this is seriously injured. The early 

 crop in one field in 1917 was damaged fully 20 per cent, while 

 with the late crop the loss in at least one case that year ran 

 as high as 80 per cent. 



The insect bores in the stem of the corn, and some beginning 

 at the internode bearing the tassel weaken this so that it 

 breaks over. Often the stalk bearing the ear is bored into 

 and many of the caterpillars enter the ear directly from outside, 

 ruining it for food. 



