SUPERFAMILY TINEOIDEA 113 



then, as one would turn a somersault, it puts its head into 

 this hole and disappears beneath the silken covering. It 

 dives in, so to speak. It remains in retirement about a day 

 and then having cast its skin, it re-emerges and begins feed- 

 ing on the surface of the leaf. 



In their second instars the larvae bite into the leaf tissue 

 from above and especially towards the borders of the leaves. 

 The feeding scars show as little brown depressions going 

 part way through the leaves. After a few days of feeding 

 the larvae make second moulting cocoons which are slightly 

 larger than the first ones. They again remain in retirement 

 about a day. In their last stage they skeletonize the leaves 

 for about a week. 



When full-fed the larvae wander about seeking a place 

 to pupate. Early in July they spin their ribbed cocoons on 

 the leaves, the young fruits, the twigs or the larger limbs. 

 In the transition zone the pupal stage of this generation 

 lasts about two weeks and the next generation of moths is 

 emerging by or before the beginning of August. Farther 

 north there is apparently but one generation of the insect. 

 The species overwinters in the pupal stage. The major part 

 of the cocoons are spun on the lower side of the small twigs 

 especially of the lower limbs. 



Bucculatrix thurberiella, the so-called cotton leaf perfora- 

 tor, has recently attracted some attention in the southwest 

 because of its actual and potential economic possibilities. 

 In 1913 it was taken by W. D. Pierce on wild cotton, Thur- 

 beria thespesoides, at various points in Arizona. Later it 

 was found attacking cultivated cotton in Arizona and in 

 1916 Mr. E. McGregor found it attacking and doing serious 

 injury to cultivated cotton in the Imperial Valley of Cali- 

 fornia. 



In life history it greatly resembles the preceding species. 

 In this case, however, the eggs are scattered on both sides 

 of the leaves and the mines which the young larvae make 



