312 MISC. PUBLICATION 657, U. S. DEPT. OF AGRICULTURE 
chusetts, eastern New York, Delaware, Pennsylvania, northern New 
Jersey, Indiana, Kentucky, Ohio, Maryland, Virginia, and West Vir- 
ginia. After the flood of the Ohio River early in 1937, elm driftwood 
containing Scolytus multistriatus was found at sever al points on the 
lower Ohio River. There is strong evidence that the beetles have 
been introduced at several different points. 
The smaller European elm bark beetle seems to confine its attacks 
to the various species of elm. The beetles show a decided preference 
for recently cut, broken, or dying material, and although they some- 
times attack living elm bark, they are not successful. The simple un- 
forked egg galleries follow the grain of the wood and are usually 
straight. The small nearly spherical eggs are deposited 1 in niches in 
the sides of the egg gallery, and average about 73 per gallery. Emer- 
gence of young adults from infested material varies according to the 
density of the initial attack and the conditions surrounding develop- 
ment. Less than 100 beetles per square foot were obtained from mate- 
rial overwintering in the field, whereas an emergence of over 600 per 
square foot was Aad from the most favorable sticks in an outdoor 
rearing cage. 
In northern New Jersey, the length of the life cycle ranges from 
45 to 60 days under favorable conditions. In this area there are two 
full generations and a partial third each year, whereas in the Boston 
area there is said to be only one generation per year. Beetles are in 
flight at all times during the summer and early part of the fall in 
the New J ersey area, with two periods of greater abundance—early in 
June and about 2 months later. Usually this introduced elm bark 
beetle passes the winter in the larval stage, and late in May or early 
in June the young adults emerge and fly to healthy elm trees, where 
they feed for some time on the bark of young twigs before they are 
ready to deposit their eggs. This habit of the beetles makes them 
very dangerous as disease vectors. In the areas where the very serious 
Dutch elm disease is present, trees suffering from this disease offer 
very favorable breeding material for the beetles. Young adults 
emerging from the infected bark carry the disease spores on their 
bodies, and in feeding later on the twigs of a healthy tree they often 
introduce these spores and the tree becomes inoculated with the disease. 
Earlier work conducted in Europe proved that both of the com- 
mon European elm bark beetles are efficient carriers of the spores of 
the fungus, and later work at Morristown, N. J., has shown that the 
smaller European elm bark beetle is the most important vector in 
this country. Control of bark beetles is discussed on pages 47-51, and 
further information on this particular species may be found by con- 
sulting Collins (99) and Collins et al. (100). 
Scolytus sulcatus ranges in color from shining brown to black. 
It is from 3.4 to 4.4 mm. “long and about twice as long as wide. The 
elytra have the punctures arranged in regular strial and interstrial 
rows of nearly equal size, the striae weakly i impressed. The abdomen 
is weakly concave on the ventral side, the fifth sternite longer than 
the preceding two combined and lacking a posterior margin in the 
male. Comparativ ely little is known of this species, except that it 
occurs in Connecticut, New York, and New Jersey and has been taken 
from the bark of plum, apple, and elm. Special interest attaches to 
the fact that it has been taken near New York City from dying or dead 
