3(T THE SUGAR-BEET WIREWORM. 



after nioltiiig. This is especially apt to be the case in the fall, when 

 they are sluggish. 



Most of the larvse observed during 1912 molted twice. A few 

 were seen to molt once, although it is possible that a molt might have 

 been overlooked in a few instances. In the case of a few others it 

 was thought that a third molt was seen, but this is doubtful. From 

 tliis it is impossible to give even the a])j)roximate number of molts 

 with any degree of accuracy, but present indications are that they 

 molt at least five or six times. 



The Pupa. 



PirPATlON. 



In about July or August the mature larvte become shorter, and 

 while they are not more constricted between the segments, they have 

 the appearance of being so, as the segments swell slightly in the middle. 

 At the same time there is a sUght change in color, the entire larva 

 appealing sickly and of a dirty yellow color. During tliis period 

 the mreworms lose most of their activity, and whatever movements 

 they make are slow and weak. When pupation is only a short time 

 off they are quite helpless, and if their pupal cells are broken open 

 they are unable to make new ones. Several which were taken in this 

 condition were able to pupate safely, the operation taking place in 

 a Janet ants '-nest cage. 



THE PUPAL CELL. 



The pupal cell is simply an enlargement at the end of the larval 

 channel, and is slightly elUptical in shape. It is unlined but is 

 quite smooth and the soil is weU compacted. The depth of the pupal 

 cell below the surface varies between 44 and 9 inches, but most of 

 those observed were at a depth of about 6 inches. It is apparent 

 that the wireworms move very little preparatory to pupating, as 

 pupa^ are often dug up with the wireworms close to the old beet 

 roots. 



SOIL CONDITIONS AFFECTING PUPATION. 



The ])U])a^ (PI. V) are unaffected b}^ a little dryness, but if the soil 

 becomes ((uite dry for a long period they do not emerge. Many 

 healthy pupae were dug up in the field in soil which contained only 

 a Mttle UK-isture. Those which came through best under laboratory 

 conditions were from cages where the soil was kept only moderately 

 damp. Where the soil was too wet a large percentage of tlio ])uj)a3 

 sickened and died. Those found dead under these conditions were 

 attacked either by a fungus or a bacterium, or sometimes by both. It 

 was not determined whether these organisms were ])arasitic or sapro- 



