1-year-old Hemlock sapling
12-18" tall

3-year-old Hemlock sapling
4 feet tall

8-year-old Hemlock
15 feet tall

30-year-old Hemlock
60 feet tall

Hemlock branch with
new growth in spring

Hemlock branch with
cones in fall

Hemlock trunk/bark

Hemlock canopy

Lightly infested branch

Moderately infested branch

Heavily infested branch

Heavily infested branch
in decline

Lightly infested tree:
few egg sacs on less than half of tree, dense foliage, bright green new growth in most recent spring

Moderately infested tree:
more egg sacs covering ½ tree,
foliage not as thick as normal, little new growth in most recent spring

Heavily infested tree:
many egg sacs covering most of tree, thinning grayish green foliage,
no new growth in most recent spring

Heavily infested tree in decline: 
fewer egg sacs, serious
defoliation, gray color,
branch die-back, no new growth

Cluster of HWA eggs laid in
early spring & early summer

HWA egg sacs most visible in
spring and early summer

HWA crawlers emerging from egg sacs
in spring and early summer

HWA crawlers compared to a penny

HWA nymphs exposed on branch
in summer dormancy

HWA adult in late winter & early summer
laying new generation of eggs

Soil injection

Soil drench

Foliar spray

Trunk spray

1.  Mix treatment solution according to
soil moisture level

2.  Pour solution into injector tank

3.  Re-measure trunk diameter at breast
height (circumference divided by pi 3.14)

4.  Inject treatment solution into soil around
base of tree (1 hole per diameter inch)

5.  Mark each tree
as it is treated

6.  Give tree extra water
if soil moisture is very low 

Sasajiscymnus tsugae

Scymnus sinuanodulus

Scymnus ningshanensis

Laricobius nigrinus
feeding on adelgid egg sacs

Oviposition jars in which
beetle eggs are laid

Tents in which beetle eggs
are reared to adults

Scientist inspecting and
counting beetle eggs or adults

Clip dish used for releasing beetles
into the forest