348 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 5 



trees were badly infested, mostly with young larvae. Their presence 

 was indicated by the exudations from the tree and the castings of the 

 larvae. The young borers work mostly in the cambium and sapwood, 

 sometimes making rather long winding chambers but more often 

 eating out a large irregular shaped cell and loosening large pieces of 

 the bark. After they have attained considerable size they bore deeper 

 into the wood. 



As some of the trees in Palo Alto were killed and others were seriously 

 threatened, some of the students in our forestry class cooperated with 

 the city of Palo Alto and all of the badly infested trees that stood in 

 the streets were treated. The entrance to the burrow when stopped 

 up Avas opened with a knife or chisel and a small pipette full of carbon 

 bisulphid was introduced into the burrow and the entrance closed by 

 being plastered over with mud. This killed all the larvae. 



The Oak Tree Cerococcus. The underside of the large limbs and 

 smaller branches of many of the live oaks is covered over with a slimy 

 mould. For a long time this was supposed to^ be only a mould growing 

 on the tree but it was found that its presence there was due to the 

 fact that a peculiar scale insect, Cerococcus ehrhorni, was there secret- 

 ing a honey dew in which this fungus grows. When these insects 

 are present in such numbers as they frequently are, they must con- 

 siderably impair the vitality of the tree.- 



If the oak tree finally succumbs to the attacks of some or all of these 

 pests, it is immediately attacked by an army of other insects that 

 live on the dying or dead wood. The Scolytidae come first, then the 

 Buprestidae, Cerambycidae, and other wood borers, so unless the 

 wood is protected it is soon destroyed. 



Fungus Disease. A peculiar disease has been doing very serious 

 damage to the live oaks in the Santa Clara Valley during the past fall 

 and winter. On many of the trees a small patch of leaves would 

 begin to turn brown, this area would rapidly spread, sometimes cover- 

 ing one side of the tree, rarely spreading over the whole tree. Seen 

 from a short distance, these patches looked exactly like a fire had been 

 burning under the tree and had leaped up and burned the leaves. 

 Many trees lost most of their leaves in this way but as soon as the 

 old leaves were off, new ones appeared and the trees seem to be 

 recovering from the attack. 



Dr. Meineche, who recently examined trees affected in this way, 

 believes the disease to be due to a fungus working in the leaves and 

 probably in the branches. 



