Report of State Board of Horticulture. 77 



with an assistant, I spent several hours in searching for them 

 without finding a single one. Neither have I found any in 

 such places in well cultivated orchards. Nevertheless I be- 

 lieve that in well cared for orchards of clean smooth trees, 

 the larvae do spin their cocoons under clods or any other 

 objects that may lie upon the surface of the soil; and that 

 frequent cultivation may thus be of value by destroying them 

 or exposing them to their enemies. August 15, 1900, I found 

 one larva in its cocoon, two live pupae and a number of empty 

 pupa cases in small cracks in the uncultivated soil under an 

 apple tree. The bark on this tree w^as rough and scaly and 

 considerable rubbish lay on the ground under it. There wer^ 

 thus many normal places in which the larvae could have sp jn 

 their cocoons; that they chose to do so in the ground would 

 seem to indicate that the habit is not unusual. Cooke states 

 that the cocoons are often found from one to six inches be- 

 neath the surface of the soil about the trunk and larger roots. 

 Simpson states that many are placed in cracks in the ground 

 and that a Mr. McPherson reports having found many among 

 the clods of earth in the orchard. Undoubtedly the larvae 

 prefer to pupate under scales of bark on the trunk and larger 

 limbs or in other dry, secluded places above the ground — 

 in breeding cages they almost invariably go to the top — but 

 it seems evident that under certain circumstances they may 

 pupate on or beneath the surface of the soil, and that clean, 

 smooth trees and clean culture are valuable aids in the war- 

 fare against this pest. 



Having found a suitable place, whether it be on trunk or 

 branch, in barrel, box or storeroom, or under a clod, the larva 

 hollows out a little oval cavity with its jaws and proceeds to 

 envelop itself in a thin, tough cocoon of silken thread inter- 

 mingled with particles of the surrounding substance. H the 

 cocoon is formed by a larva of the first brood, in July or early 

 August, in two or three days it will undergo a wonderful 

 transformation — a complete change of form. It is then a 

 pupa. A larva of the second brood remains as a larva within 

 its cocoon until the following spring, when it too transforms 

 to a pupa. Whether the change to the pupa occurs in a few 

 days as in the first brood or is delayed until spring as in the 



