year. There are one and possibly two generations per year, depending on locality. 
Keeping the bark smooth, especially at the base of branches, has been recom- 
mended for control on dogwood (/239). 
The rhododendron borer, S. rhododendri (Beutenmiller), attacks rhodo- 
dendron and sometimes laurel and azalea in the Atlantic Coastal States. The adult is 
blackish, except for various white and yellow markings, and has a wingspread of 10 
to 15 mm. Mature larvae are up to 15 mm long. The winter 1s spent as a full-grown 
larva in the stem of its host. Pupation occurs in the spring, and the adults appear 
during May and June. Eggs are deposited on the bark, and the larvae bore into the 
stems, Causing ugly scars and sometimes killing large branches and small plants. 
Cutting out and burning infested parts of plants and the use of two to three well- 
timed insecticide applications are recommended control practices (908). 
The maple callus borer, S. acerni (Clemens), is widely distributed in southern 
Canada and throughout the Eastern United States south to Florida. Its hosts are 
sugar and red maples. The adult is amber colored and has a wingspread of 20 to 25 
mm. The head is orange-yellow and there is a red tuft of hairs at the posterior end of 
the yellow-banded abdomen. Full-grown larvae are white and from 14 to 19 mm 
long. 
Adults appear in May and June and deposit their eggs in roughened places on the 
trunk, preferably on or near wounds. The larvae bore through the bark and into the 
sapwood. Slightly wounded trees are often severely damaged. Winter is spent in the 
larval stage and pupation occurs in the spring. Just before it changes to an adult, the 
pupa wriggles part way out of its burrow. When the adult emerges, the cast pupal 
skin is left sticking out of the bark. There is one generation per year. Smoothing 
roughened bark areas, removing borers from under the bark in the spring, and 
painting wounds are recommended control practices. The southern form attacks 
silver maple in Florida and Georgia. 
The pitch mass borer, S. pini (Kellicott), occurs in eastern Canada and the 
Eastern United States southward to Georgia and Tennessee and westward through 
the Great Lakes region. Its preferred host apppears to be eastern white pine but it 
also attacks Austrian and Scotch pines and spruce. The forewings are blue-black, 
with a metallic-green luster, and have a wingspread of 25 to 30 mm. There is an 
orange band on the fourth abdominal segment and a tuft of orange scales at the tip 
of the abdomen. Mature larvae are white to pink and 25 mm long. 
Eggs are deposited on the bark during June and July, usually near a wound, on 
old scars, or just below a branch. The larvae bore in the inner bark and sapwood, 
excavating more or less transverse tunnels, and cause copious flows of pitch. This 
pitch accumulates in masses 8 to 10 cm in diameter at the entrance hole. Pupation 
occurs in the pitch mass, and when the moth emerges the empty pupal case is left 
sticking out of the mass. The life cycle requires 2 to 3 years. Although not a killer 
of trees, this species causes some lumber degrade as a result of its activities. No 
practical control methods are known for use on forest-grown trees. Borers in shade, 
ornamental, or park trees may be removed with a knife. 
Several other species of Svnanthedon also occur in eastern North America. S. 
geliformis (Walker) 1s a bark borer in dogwood and pecan. It also infests cynipid 
galls on the trunks and branches of oaks, and diseased and injured tissues of various 
other plants. The apple bark borer, S. pyri (Harris), attacks apple, hawthorn, 
serviceberry, and mountain-ash. The larvae excavate shallow, tortuous tunnels in 
and beneath the bark of trees usually injured by storms and disease, causing the 
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