[February 1S91. 



PSYCHE. 



29 



stance of a young orchard having been 

 planted close to a last year's melon patch. 

 which was not replanted this year. The bee- 

 tles undoubtedly bred upon the melons last 

 season and hibernated in large numbers. 

 The present spring, finding no more appro- 

 priate food at hand they took to the young 

 plums and apricots merely as a substitute. 

 We have little fear, therefore, that a new 

 habit has been formed." 



What basis the authors had for the 

 positive statement that the beetles bred 

 upon the melons I am unable to say, 

 but it is more than probable from what 

 is now known of the life-history of the 

 insect that many of the beetles had de- 

 veloped instead on the roots of the corn. 



These references and quotations will 

 serve my purpose of presenting the in- 

 sect as it was known to entomologists 

 during the time which they cover. It is 

 to be noticed that no reference is made 

 to the larva except that implied in the 

 statement made by the editors of Insect 

 life to the effect that the beetles breed 

 upon melons. If these authors had 

 known at the time their notice was writ- 

 ten that larval Diabrotica 12-punctata 

 feed on the roots of corn we may assume 

 that they would have mentioned it in 

 reporting a case in which the relation 

 between the injury to the trees and the 

 corn-infesting habit is so evident. 



During the years 1882 and 1883 Prof. 

 S. A. Forbes made a thorough study of 

 the related D. longicornis, which 

 affects the roots of corn in Illinois and 

 other middle states. In this region D. 

 12-punctata is a very common species, 

 occurring everywhere in gardens and 



fields on flowers. With the thorough 

 examination of insects from the roots of 

 corn which to my knowledge was made 

 by him, it is altogether unlikely that it 

 would have escaped notice if its larvae 

 had then been present in any numbers 

 in corn fields. 



In the report for 1SS7 (published in 

 iSSS) of the Entomologist of the Na- 

 tional Department of Agriculture, Mr. 

 F. M. Webstei states in a brief notice 

 that while in Louisiana in 1SS6 : 



"We frequently heard of fields of young 

 corn being seriously injured, during some 

 seasons, by a small white worm which at- 

 tacked the roots, usually during April. From 

 the description given us of the pest and its 

 manner of attacking the plants, we first 

 thought it might be the larva of D. longi- 

 cornis, as the habitat of that species is known 

 to extend southward to Central America. On 

 April 12 of tne present year [1S87] we were 

 enabled to solve the problem by finding con- 

 siderable numbers of these larvae in a field of 

 corn in Tensas Parish, La., where they were 

 working considerable mischief by killing the 

 young plants. As observed by us, their 

 mode of attack differed from that of their 

 northern congener in that they did not ap- 

 pear to attack the fibrous roots or bury them- 

 selves in longitudinal channels excavated in 

 the larger roots. On the contrary, they bur- 

 rowed directly into the plants at or near the 

 upper whorl of roots, which almost invariably 

 resulted in the death of the plant. . . . Both 

 of these fields had produced cotton the pre- 

 ceding year. The adult beetles were fre- 

 quently seen before we observed the larvae, 

 but they were not abundant about the plants 

 in the corn fields, being usually on the yellow 

 blossoms of a species of Aster which springs 

 up in cultivated grounds early in the spring 

 in great abundance. No pupae were found, 

 although careful search was made for them." 



