20 MONTANA EXPERIMENT STATION BULLETIN 457 



ASH 



GREEN ASH APHIS (Prociphilus venafuscus) 



In the vicinity of Hamilton, green ash is severely infested 

 every year by this aphis species. To date, it has not been reported 

 from other areas of the state. The principal damage occurs to the 

 leaves on which the aphis feed in the spring and early summer. 

 Their activities result in curling of the leaves and reducing 

 terminal growth. This insect overwinters in the egg stage in cracks 

 in the bark and trunk and on the main laterals of the ash tree. As 

 soon as the buds begin to swell, the aphis eggs hatch and the 

 young migrate to the leaf buds and commence feeding. During 

 June and July, winged forms appear which migrate to an alternate 

 host, returning again to the ash in September and October. These 

 winged adults produce wingless forms which ultimately produce 

 the over-wintering eggs. 



GENERAL 



FOREST TENT CATERPILLAR (Malacosoma disstria) 



The forest tent caterpillar was one of the most conspicuous 

 insect pests of shade and fruit trees during 1948. A severe outbreak 

 of this insect occurred in the city of Billings, causing considerable 

 damage where, in some cases, complete defoliation of smaller trees 

 was observed. Extensive control measures were applied against 

 this pest. 



COTTONWOOD LEAF BEETLE (Chrysoviela scripta) 



Reports have been received of damage caused by the cotton- 

 wood leaf beetle to cottonwood trees in shelter belts. This insect 

 occurs over all parts of the state but it has been reported as doing 

 the most damage to trees in the western and northern counties. 



BRACHYRINUS MERIDIONALIS 



This insect has been a pest of lilac and other shrubs in some 

 sections of the town of Hamilton for several years. Up to this time 

 it has spread very little from the point of its initial introduction 

 into Hamilton. This insect is a European species which has been 

 previously noted only in the San Francisco bay region. The adult 

 beetles are active mainly at night at which time they damage lilacs 

 and other shrubs by completely defoliating them. They may be 

 found during the daylight hours hiding under the trash and other 

 debris in the immediate vicinity of the shrubs on which they are 

 feeding. This pest is similar in appearance to the strawberry root 

 weevil. 



