28 
i 
Fig. 36. Trunk of ash, in one of the parks in Chicago, showing injury 
by the Lilac Borer, Podosesia syrinyix. 
on the trunks and branches of which it produces large, rough, scar- 
hke outgrowths from knots, roughened places, or wounds, by un- 
dermining the bark and boring into the wood. (See figures 25 and 
26.) 
The eggs are laid in summer in masses on rough, scarred, or 
knotty places. They hatch in about six days and the young borers 
eat thru the bark into the outer layers of the sap wood, where 
they mine irregularly about, penetrating the harder wood and go- 
ing to the center of small branches. (Fig. 27.) In fall, when they 
are nearly or quite full grown, they make a hibernating cell by 
plugging up the burrow both before and behind with frass, and 
there they pass the winter as larv^. They do practically no bur- 
