338 REPORT OF STATE BOARD OF HORTICULTURE. 



The woolly aphis is subject to the attacks of a number of natural enemies, 

 including the parasitic chalcis fly (^p/ie?imtsm«Z?'Haldemann), and the larva 

 of a syrphus fly (ripiza radicum, Walsh and Riley), and also the larva and 

 adult of several species of ladybirds, the larvae of lace-wing flies and spiders, 

 etc. In the east a very small brown species of ladybird [Scymnus cervicalis 

 Muls.), is often present in some numbers, and the common nine-spotted 

 ladybird {Coccinella 9-notata), is also an active enemy of the woolly aphis. 

 The nine-spotted ladybird has been used very successfully in California, on 

 the authority of Mr. Ellwood Cooper, to rid trees of root-lice, which was 

 effected by colonizing the larvte of the ladybird at the base of the infested 

 tree. All the parasites mentioned do much to keep the root-lice in check, 

 and in the case of old well-established trees are in most instances a suffi- 

 cient protection, but in the case of young trees and nursery stock, where the 

 damage from the louse is much more rapid and serious, the use of the 

 'direct remedies outlined should not be neglected, and particularly should the 

 nursery treatment be insisted upon. 



THE FRUIT-TREE BARK-BEETLE. 



( ScolytuH rugulosus Ratz.). 



By J. M. Stedbian, Entomologist. 

 SUMMARY OF RESULTS. 



From the observations and experiments conducted by this station during 

 the past two years on fruit-tree bark-beetle, the following results are briefly 

 summarized : 



1. The fruit-tree bark-beetle is increasing rapidly, and is annually doing 

 more and more damage and attracting the attention of fruitgrowers. It 

 infests the plum, cherry, apricot, nectarine, peach, apple, pear, and quince. 



2. The adult insects perish each fall, the winter being passed by the 

 larvae within the infested tree ; and these transform to adults which emerge 

 from the tree usually about the latter part of IMarch. 



3. The adult beetles make minute holes through the bark, and they and 

 their larvae mine a burrow just beneath the bark, thus destroying the cam- 

 bium layer and killing the limb above. 



4. While the fruit-tree bark-beetle is almost sure to attack first of all 

 unhealthy, injured or dying trees or parts of trees, they will attack and 

 injure apparently perfectly healthy trees. 



5. This bark-beetle is much more difficult to control than other fruit-tree 

 borers, but maj' be successfull,y held in check by careful attention to the 

 following : 



First — Clean culture is of first importance ; every tree or part of a tree 

 that is badly infested or is dying from any cause whatsoever should be 



