
en 
Combination sprays containing molasses most toxic to both larvae 
and adults of gladiolus thrips.--The apparent efficiency of molasses 
aS a component of a nicotine sulphate spray against larvae of the gla- 
diolus thrips (TaeniothripS gladioli M. & S.), as indicated by labora— 
tory experiments and reported last month by H. H. Richardson, of the 
tropical greenhouse, led him to compare the efficiency of molasses and 
brown sugar as components of Paris green sprays against the adult thrips. 
The results "indicate clearly that the combination of Paris green with 
molasses is equal to, if not surpassing, in efficiency the brown-sugar 
spray. Apparently the molasses sprays act faster. This might be ex- 
pected when the fact is taken into consideration that molasses wets 
the foliage more efficiently than does brown sugar." 
/ 
FOREST INSECTS 
Long-distance migration of mountain pine beetle indicated.—- 
A. L. Gibson, of Coeur d'Alene, Idaho, reports: "An interesting contri- 
bution to our knowledge of the flight potentials of the mountain pine 
beetle (Dendroctonus monticolae Hopk.) is now occurring within the Sheep 
Creek Canyon, an area of lodgepole pine some 10 miles south of Dillon in 
which an outbreak of this insect was reported in 1950. -A large percent— 
age of the infested trees were treated in the spring of 19351, not more 
than 1,000 being left untreated. A survey of the area in the fall of 
1931 showed some 23,000 trees recently attacked. Though difficult to 
prove, this extremely heavy attack could only be satisfactorily explained 
through a flight of beetles from some of the neighboring heavily infested 
areas, as it was not believed that there were sufficient untreated trees 
left on the area to permit such an increase in infestation. Though no 
control measures were taken in the spring of 1932, * * * a survey of the 
area. during October showed 143,000 infested trees. An increase of this 
magnitude could not have originated within the area and the beetles must 
have come from the nearest infestation some 25 miles away, with untim— 
bered areas between. Though this seems to show rather conclusively that 
the mountain pine beetle either flies or is carried by favorable air 
currents for at least 25 miles, it does not give us any information as 
to the maximum potentials of the spread of such outbreaks." 
om 
brood analysis of the Douglas fir beetle (Dendroctonus pseudotsugae 
Hopk.). Seventy-six square feet of bark surface were intensively examined 
on 12 Douglas fir trees attacked in 1932 by this beetle. Although there 
were on an average 8 1/2 attacks per square foot of bark surface, these 
produced only 1 1/2 insects per attack. Such an increase is barely 
sufficient to maintain the infestation at its present intensity. Coe- 
loides brunneri was.the most important agency in reducing the potential 
infestation, as 60.1 per cent of the Douglas fir beetle brood had been 
parasitized by this insect." 
