93 



THE CHKYSALIS. 



When the larva attains its growth it descends to the ground, into 

 which it goes to pupate. In doing this it usually selects some place 

 where the earth is rather firm, seeming to prefer the security a 

 compact soil can give to ease in digging. It digs a hole into this 

 several inches in depth, apparently cementing the dirt as it goes 

 downward, so that when it reaches the desired depth there is a 

 smooth channel from the bottom to near the surface, there being a 

 thin film of dirt over the entrance. This hole, as I found in digging 

 about corn hills, is about a third of an inch in diameter, larger at 

 the bottom than at the top, apparently so as to give free motion to 

 the chrysalis, and usually bent in its course so that the lower part 

 would have an inclination of often as much as forty-five degrees. 

 I found the chrysalis at the bottom of this, the small end down- 

 ward. In one instance I found a hole so bent that the chrysalis 

 occupied a horizontal position. 



In speaking of this habit, Mr. Wm. Frelease, as quoted by Pro- 

 fessor Comstock, says : 



"In deep breeding jars, with four or five inches of soil, I found 

 that the .larvae of Heliothis went several inches from the surface 

 before forming their cocoons, but did not notice a passage leading 

 down. As I did not notice very closely, such a tube may have 

 been there, but I think, if so, I should have seen some trace of it. 

 In all cases there was a thin film of silk. In the fields I saw 

 numbers plowed up, but did not dig for any with care. Of course 

 the plowing would have destroyed such a tube, but I sometimes 

 found the silk about the pupa, though always more or less torn." 



The observations upon which the article in the Seventh Illinois 

 Entomological Keport was based were made during the winter of 

 1877-78. I began digging for the chrysalids in November in a field 

 where the worms had been abundant in the corn, using at first a 

 spade and digging at random. I had expected to find them in 

 "oval cocoons,'* as they were supposed to make, but cutting across 

 channels in which I afterwards found chrysalids led me to dig a 

 little more carefully. I soon found that by running the spade along 

 the row and taking off half an inch or less of the surface^ I could 

 tell where every chrysalis was to be found. The following passages 

 from my note book kept at the time may perhaps be more satisfac- 

 tory than any other way of stating it : 



In digging around corn hills this afternoon I found several chrys- 

 alids, and one feature seemed strange or new. Instead of an oval 

 cocoon, as is usual with most of our Noctuidse, they were at the 

 bottom of a round chamber that came almost to the top of the 

 ground, nicely smoothed within, and the lower end from three to 

 four inches from the surface. Sometimes these were perpendicular, 

 with the chrysalis resting on the small end in the bottom ; at other 

 times the top of the hole seemed perpendicular, while the lower 

 part bent to one side and the chrysalis lay on its side, the head 

 towards the opening or top. The cavity within was of about a third 

 greater diameter above than the chrysalis, but the lower part was a 

 little larger. The soil was damp, but dry enough to crumble when 



