August, '12] DOANE: LIVE OAK INSECTS 347 



the live oak. One has been called the ''white blotch oak leaf-miner" 

 on account of the characteristic white blotch on the upper side of the 

 leaf. The larvae work only in the upper layer of cells, making a 

 rather large irregular blotch in which they finallj' pupate after spin- 

 ning a flat, loosely constructed web. Like other members of this 

 genus, Lithocolletes, the larvae undergo an interesting change during 

 development. The leaves of the white oak and the blue oak are at- 

 tacked by the same species and sometimes seriously affected. 



One of the other leaf-miners makes a long serpentine burrow which 

 gradually grows wider as the larva increases in size. When it is full 

 grown it drops to the ground and spins a small, rather closely woven 

 brownish cocoon. 



The other species, Buccidatrix, makes a dense brown blotch and a 

 short serpentine mine which is distinctly ^^sible on both sides of the 

 leaf. 



Part of the larval stage is spent as a miner and part as a surface 

 feeder. The moult takes place under a circular white silken web 

 on the under surface of the leaf. We have not yet determined the 

 length of the different larval stages, but the typical ribbed Buccida- 

 trix cocoons are made in Maj^ and June, the adults issuing a little later. 

 The leaf-folders that simply fold over the edge of the leaf and the leaf- 

 tiers that fasten two leaves together for protection while feeding, are 

 often abundant enough to seriously affect the appearance of the tree, 

 especially in May when the new growth comes. 



Twig Girdler. During the last three years the California oak twig 

 girdler (probably a species of Agrilus) has been increasing to an alarm- 

 ing extent. A few years ago the work of this insect was rarely noticed 

 on the trees but now the beauty of many of our noblest trees is sadly 

 marred. The larva evidently enters close to the tip of the twig in 

 the tender new growth. At first it works in the center of the twig 

 but as soon as it reaches the harder wood it works just beneath the 

 bark in the cambium and sap wood. As soon as it enters the cambium 

 it begins working down the t-v\ng in a spiral, thus effectively girdling 

 and killing it. 



As the larvae enter the twigs early in summer and work all winter 

 until about June, they often kill quite large twigs. When scores of 

 these pests are at work on a tree, the whole tree soon looks brown and 

 ragged and presents a very unpleasing sight. 



The Carpenter Worm. Early last fall our attention was called to 

 certain oak trees that were dying. An examination showed that the 

 trees were badly riddled by the carpenter worm. The greater part 

 of the cambium was destroyed and the larval burrows were every- 

 where throughout the wood. Later we found that scores of other 



