THE CANADIAN ENTOMOLOGIST. ' 159 



then, bending the thread, it was advanced over the space between two of 

 these (that is, about one-hundredth of an inch) to the point where it 

 leaves one rib to proceed to the next one. 



But thus far we have each rib composed of only two threads and the 

 transverse lines running in only one direction. How is it as to the other 

 set of obliquely transverse lines which cross the first set ? and how are 

 the two additional threads added to each rib ? All of this is done pre- 

 cisely as the first set was made. Returning from the side g ^ of the 

 frame, the work is only a repetition in the opposite direction of the work 

 first done as above related. Having finished about three-fourths of the 

 frame, retreating from it and working towards itself, as above stated, the 

 larva now passes up into it, adding to the floor and the foundations as it 

 goes, till having reached the upper end, it doubles upon itself, and reverses 

 its position, protruding about one-fourth of its body through the open end 

 of the frame, which it now begins anew from the other end and repeats 

 here the work already done, until the two portions almost touch. Then 

 it ceases to follow the regular pattern of the reticulation, and by a series 

 of longitudinal threads passed rapidly to and fro, connects the two pieces 

 of the frame much as a tailor darns a rent in a garment, and this darn 

 may be detected even in an old cocoon. The larva is now completely 

 enclosed in the frame work, and immediately begins to spin its cocoon 

 proper Avithin it. This occupies only the central position, not extending 

 into either end of the frame. It works very rapidly, and in three hours 

 from the time that it begins to spin is entirely concealed from sight. 



It is very interesting to watch the little architect at work upon its 

 reticulated frame. It evidently understands its trade, whether we call it 

 a house-builder or weaver. It knows exactly what it has to do, and how 

 to do it, and " goes straight along " with its work with an air of as much 

 conscious intelligence and understanding as any other builder of homes 

 either with or without hands. It is difficult to watch its operations with- 

 out feeling that here is a conscious intelligence at work. All other known 

 species of the genus, save one, make these ribbed cocoons, and to do so 

 they must work much as this one does. How the instinct to make a 

 cocoon, and especially one like this, ever originated — -what advantage in 

 " the struggle for existence " the reticulated pattern possesses over a 

 common one in which the threads are carried hither and thither appar- 

 ently without order or plan — and why this instinct should be lacking in a 

 single species, are questions as unanswerable as why some spiders are 



