20 



was done by this insect. Professor Cordley has succeeded in making 

 some o])servations upon this leaf-feeding habit which are of great 

 value. In a recent hotter to the writer he details his experiences as 

 follows: 



It was found on June 4 tluit these eggs had hatched and nearly all of the larviu were 

 dead. Two of them, however, had fed upon the leaves, were yet alive, and had made 

 some growth, notwithstanding the fact that the leaves had been taken from the tree 

 nearly a month before and were therefore presumably not in the most palatal)le ( o - 

 dition. Both larv;o were feeding upon the lower parenchyma of the leaf, ami one 

 had completely covered itself with a web holding pellets of frass. A recently hatched 

 larva, mounted in l)alsam, measured 1.35 mm. in length; the larger of these two 

 larvje at this time measured 1.80 mm. in length and was proportionately stouter. 

 Both were transferred to fresh leaves, upon which they fed until June 8, when one 

 of them disappeared. The other continued to feed until June 11, when it too disap- 

 peared. However, I noticed a slight discoloration of the midrib of the leaf, near 

 where this larva had been feeding, and on carefully opening it found the larva feeding 

 as a miner, it having already excavated a tunnel about 15 mm. long. I then examined 

 the other leaf, in which I found the larva that had disappeared three days before 

 likewise feeding in the interior of the midrib. The larv;e were again transferred to 

 fresh leaves, and by the following morning each had again disappeared within a midrib. 

 Both lai'va; continued to feed within the nntlribs until June 16, when one of them, 

 on being transferred to a fresh leaf, refused to eat and soon died. The other, with 

 occasional changes t(j new pastures, continued to thrive until June 25, when it waa 

 plump and active and apparently in the best of health and spirits. Unfortunately 

 I was then absent from the laboratories for some days, and when I returned the 

 larva was dead. I believe that with careful attention it could have been brought to 

 maturity on a diet of leaves alone. When one considers that it lived and grew for 

 more than three weeks ui)on leaves that had l)een severed from the tree sometimes 

 for several days, and that it was apparently more thrifty between June 16 and 25 

 than in the earlier days of its existence, one must acknowledge that, while the i>roof 

 is by no means positive, the indications are that codling moth larvse may fully 

 develop on a diet of perfectly fresh apple leaves without ever having tasted fruit. 

 (See PI. II, fig. 1.) 



The writer has many times taken larvie from apples and placed 

 them upon leaves in cages and bottles. It was found that the larvffi 

 would fasten the leaves together with silk and eat holes in them; ])ut 

 on account of lack of attention no larvaj were bred to maturity. The 

 writer believes, and agrees with Professor Cordley in believing, that 

 the larvie with proper care can be brought to maturity on the leaf 

 diet alone. 



This (|uestion of the leaf -feeding habit of the codling moth is one of 

 the most important questions in the life histor}' of the insect, and 

 should especially commend itself to entomologists for future investi- 

 gation, since not only will it give us a very important biological fact, 

 but it will also prove very definitely how spraying is elective against 

 the insect. 



It has often been recorded that larvte gnaw cavities in rough rotten 

 wood, bark, cloth, paper, and other places where the}' spin cocoons, 

 and the bits of these substances incorporated in the cocoons. From 



