2() ANNUAL HK PORTS OF DEPARTMENT OF AGRICULTURE, 194 
AMBROSIA BEETLES 
Ambrosia beetles damage green logs and lumber, particularly of 
hardwoods, and their extensive tunnels and the stains caused by 
associated Fungi constitute one of the most serious problems of the 
lumber industry in the Southern State-. Logs and Lumber may 
be reduced in value more than 50 percent within a few weeks. Chem- 
ical sprays for treating green logs and Lumber have been tested in 
Louisiana since 1JW4. but satisfactory results were not obtained until 
L939, when several chemicals gave consistent protection. Some of 
these also protected against sap stain. Unlike the simple chemicals 
used for controlling powder-post beetles, those effective against am- 
brosia beetle- are complex but not too expensive: one is dichloro- 
diphenyl oxide, which is now being tested on a commercial scale 
in the (oilf States. A simpler method of preventing attack by 
ambrosia beetles is to end-rack lumber for 12 to If) days. This 
will reduce the moisture content, which may be as high as 45 to 
52 percent, to a point where ambrosia beetle- will not attack. 
Biological studies were begun at Saucier. Miss., in the spring 
of 11)39. At the same time cooperative studies on the identity and 
biology of the associated stain fungi were instituted. Data on live 
species of ambrosia beetles in the genera Platypus^ Xyleborus, and 
Pterocyclon indicate that, while there is considerable difference in 
habits, the most important species complete their life cycle in from 
6 to 8 weeks in the Gulf States, and that the peak of activity i- 
during July and August. 
EUROPEAN SPRUCE SAWFLY 
The European spruce sawfly is generally distributed throughout 
the spruce areas of New England and New York. During 1939 there 
was little change in its stattis over the entire region, but -nine of 
the severely affected areas increased considerably in size. In north- 
ern and eastern Maine there are heavy infestations in several town- 
ships, and in southern Vermont and southern New Hampshire heavy 
infestations increased in wide circles; so about 100 square miles ate 
seriously affected in each of these two States. Up to the present 
there has been low mortality among trees severely defoliated by the 
sawfly. This is largely due to the fact that the larvae of the sawfly 
feed almost exclusively on the old needles, and enough of the current 
year'- foliage remains to keep the trees alive, During 1939 an inten- 
sive study was undertaken to measure the sawfly populations causing 
various degrees of defoliation, the factor- influencing these popula- 
tion-, and the effect of defoliation <>n the tree-. Study plots were 
established in areas throughout the region where types of growth 
and climatic conditions differ considerably. 
One of the outstanding developments during the r.>.*> ( .> season was 
the tremendous Larval mortality caused by disease in area- where 
Larvae were excessively abundant. A- a result of this mortality 
there was a marked reduction in the infestation in such area- and 
a Likelihood that little defoliation would occur there in L940, Prom 
L0 to 60 percent of the overwintering cocoon- were killed by mam- 
mal- and predaceous insects. Several shipments of imported Euro- 
pean parasites were received from Canada and liberated throughout 
