2-month-old hemlock seedling
2" tall

1-year-old hemlock sapling
12" tall

3-year-old balled & burlapped hemlock sapling
4' tall

8-year-old hemlock
15' tall

30-year-old hemlock
60' tall

Hemlock root flare

Hemlock trunk / bark

Hemlock canopy

Hemlock branch with new
green growth in spring

Hemlock cones in summer

Hemlock cones & seeds in fall

Normal needle shedding
in spring & fall

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-green color,
limb 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

Application Methods

Soil injection

Soil drench

Dry tablets (Imidacloprid only)

Foliar spray

Trunk spray (Safari only)

Soil Injection Sequence

1.  Mix treatment product with water & shake well
(use WARM water for powdered product).
Wear gloves.

2.  Pour mixture into injector tank
through funnel and paper paint filter

3.  Measure trunk diameter at breast
height (circumference divided by pi 3.14).
Read to zero mark if using diameter tape.

4.  Per dosage card, inject treatment material
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 

Soil Drench Sequence (not trench)

1.  Mix master batch of treatment material & shake well
(use WARM water for powdered product).
Wear gloves.

2.  Measure trunk diameter at breast
height (circumference divided by pi 3.14).
Read to zero mark if using diameter tape.

3.  Per dosage card, measure specific amount of
treatment material into pouring container & add more water

4.  Scrape back ground cover
& make holes in soil close to base of tree

5.  Pour measured amount of treatment material
around base of tree. 

6.  Mark each tree as it is treated 

Dry Tablet Application Sequence

1.  Measure trunk diameter at breast
height (circumference divided by pi 3.14).
Read to zero mark if using diameter tape.

2.  Check dosage card to determine
total number of tablets needed.
See Resources page.

3.  Scrape back ground cover
& make holes in soil close to base of tree

4.  Insert tablets into holes, distributing them evenly
around tree.  Wear gloves.

5.  Press holes closed

6.  Mark each tree as it is treated 

Basal Trunk Spray Sequence

1.  Put WARM water in mixing jug for master batch
of treatment material.  Wear gloves.

2.  Add Safari granules
using special measuring cup & shake well

3.  Measure trunk diameter at breast
height (circumference divided by pi 3.14).
Read to zero mark if using diameter tape.

4.  Per dosage card, put specific amount of
treatment material into sprayer through filter

5.  Spray entire contents of sprayer slowly onto trunk
from 5 1/2 feet to 6 inches above ground.
Weare gloves, goggles, mask, and long sleeves.

6.  Mark each tree as it is treated 

Predatory Beetles that feed on adelgids

Sasajiscymnus tsugae

Scymnus sinuanodulus

Scymnus ningshanensis

Scymnus coniferarum

Laricobius osakensis (male)

Laricobius osakensis (female)

Laricobius rubidus

Laricobius nigrinus
feeding on adelgid egg sacs

Beetle Rearing Highlights

Oviposition jars in which
beetle eggs are laid

Tent in which beetle eggs
are reared to adults

Scientist inspecting and
counting beetle eggs and adults

Clip dish used for releasing beetles
into the forest

Fungal Diseases
Additional information can be found in Pests of Hemlocks - Fungal Diseases. 

Fabrella needle blight
caused by Fabrella tsugae

Hemlock rust caused by
Melampsora abietis-canadensis,
Pucciniastruin myrtilli,
or Pucciniastrum hydrangeae

Rosalinia needle blight caused by
Hypoxylon herpotrichoides
(formerly known
as Rosellinia herpotrichoides)

Tip / shoot blight caused by
Sirococcus tsugae

Insects & Mites
Additional information can be found in Pests of Hemlocks - Insects & Mites.

Bag worm

Elongate hemlock scale

Hemlock borer larval gallery

Hemlock looper

Rust mite damage on hemlock

Indian wax scale

Spruce spider mite damage