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MASS. EXPERIMENT STATION BULLETIN 343 



into new localities. After feeding, the beetles fly to the trunks and larger 

 branches of dead or weakened elms or to recently cut elm logs to lay their 

 eggs in tunnels which they dig beneath the bark. These egg tunnels are 

 made by the female beetles and are characteristically parallel to the grain 

 of the wood and bark (Figure 6, upper left). They may be from less than 

 one inch to about four inches in length. Eggs are laid close together along 

 both sides of a tunnel. Tiny larvae or grubs hatch from the eggs and burrow 

 more or less across the grain (Figure 5, C). They shed their skins several times 



Figure 5. Beetle Carriers of the Dutch Elm Disease. 



A. Side and top views of Scolytus multislriatus adult. Greatly enlarged. 



B. Side and top views of Hylurgopinus rufipes adult. Greatly enlarged. 



C. Scolytus multi striatum larva or grub. Greatly enlarged. (Reproduced from Cornell 

 Ext. Bui. 290.) 



Note: Grubs of Hylurgopinus rufipes are very similar to those of Scolytus 7nultistriatus. 



as they grow. When full grown, they go through a transformation beneath 

 the bark at the end of these side or larval tunnels, and become adult beetles. 

 The young adults then dig out through the bark leaving the many shot- 

 hole-like openings previously mentioned. When the beetles breed in diseased 

 elms, many more individuals of the next generation will be carriers of the 

 fungus, because the sticky fungus spores form abundantly in the brood galleries 

 of diseased trees. 



Several species of tiny mites which are considerably smaller than the beetles 

 also live in these tunnels. Some of these may be carried to new trees on the 



