June, '13] HASEMAN: UNSPOTTED TENTIFORM LEAF MINER 315 



pupate. Not infrequently it has been found to fold over the edge of 

 the leaf and feed to a slight extent in a new place, though such cases 

 are rare. The caterpillar on preparing to pupate draws over a portion 

 of the edge of a leaf or folds over the edges at the tip of the leaf by- 

 means of silk threads and after lining this with silk it pupates, coming 

 out a week to ten days later as the moth. It is interesting to watch 

 the caterpillar tugging away at the silk threads as they are being at- 

 tached and to see it tie these into bundles so as to shorten them and 

 thereby draw down the edge of the leaf. There would seem to be 

 quite a period between the appearance of the moths and the time at 

 which the first eggs are deposited. 



In the development of the caterpillar it passes through four larval 

 stages. In the first stage it is footless, snow white except for a slight 

 tinge of yellow on the head, and somewhaf'resembiing a minute flat- 

 headed borer. In this stage the larva makes the serpentine mine 

 and in it changes to the second larval stage. This is also footless 

 and white except for the head which becomes brownish and the first 

 thoracic segment begins to take on a dorsal, black blotch. While 

 in this stage the mine is transformed into a blotch mine. With the 

 change to the third larval stage, which occurs in the blotch mine, 

 the head becomes darker, the thoracic blotch begins to take on the 

 appearance of four irregular blotches and the six thoracic and eight 

 abdominal legs appear. In this stage the larva increases in size 

 rapidly and the body becomes darker. It is usuall}- during this stage 

 that the blotch mine is transformed into the characteristic tentiform 

 mine. The change to the fourth larval stage takes place in the tenti- 

 form mine and usually Ijefore much of the chlorophyll layer of cells 

 is consumed. In this stage the caterpillar has a brownish head with 

 four dorsal black spots and four similar ones on the first thoracic 

 segment and the body is dark grey with regular rows of white tubercles 

 Ijearing prominent hairs. After feeding in the mine until mature the 

 larva leaves it and prepares to pupate. 



The unspotted tentiform leaf miner will probably never prove to 

 be an exceedingly important pest of the orchard. (3ne can hardly 

 conceive of its ever becoming more abundant than it has been in the 

 orchards of Missouri for the past two years and there is little sign 

 of its having seriously injured either the trees or the apple crop the 

 past summer. In case it does require special attention it can be 

 checked by early spring plowing for the destruction of the leaves 

 containing the wintering pupte. Spraying has been carried on in 

 the orchards here and has not had the least effect upon the devel- 

 opment of the insect, due to the fact that the caterpillar is never ex- 



