Tree Squad gets rid of Sawflies

The following scales are common on landscape trees throughout the Twin Cities. Most scale identification will require an experienced professional with a hand lens in order to be correctly identified.

Yellowheaded Spruce Sawfly (Pikonema alaskensis)

White, black, red, Colorado blue and Norway spruces

What you will see:

  • Loss of foliage
  • Especially noticeable towards the top of ornamental spruces
  • Often the tips of branches are stripped
  • This is caused by feeding on old and new needles

Life cycle:

  • Adult Sawflies emerge in late May
  • Females will then lay an egg at the base of needles
  • Eggs hatch in approximately a week
  • Larvae appear on new foliage from early June to late July
  • The Sawfly will hide in a cocoon over winter as a pupa

White Pine Sawfly  (Neodiprion pinetum)

White Pines

What you will see:

  • Feeding and loss of needles on old and new foliage
  • Pale yellow larvae with black heads and four rows of black dots going down

Life cycle:

  • Larvae hibernate in topsoil, surrounded by a cocoon
  • In the spring, adults emerge and lay eggs
  • The larvae feed on needles through September
  • Only one generation per year

Pine Sawfly  (Neodiprion spp.)

Prefers mugo and table top pines.
May also attack scotch, red, jack, and Japanese pines. Rarely, the pine sawfly will also feed on white, Austrian, ponderosa, shortleaf, and pitch pines.

What you will see:

  • Needles turn brown and wilt, appearing straw-like
  • Older foliage will be removed
  • Heavily infested trees will end up with a “bottle brush” effect, with older needles missing and new Needles intact

Life cycle:

  • Eggs hatch in April through mid-May
  • Larvae will feed in groups, three or four on a single needle, until mid-June
  • Mature larvae drop to the ground and form cocoons
  • Adults emerge in late August to September. They mate and lay eggs
  • Females lay their eggs in slits along the edge of needles, where they can survive the winter.

Redheaded Pine Sawfly  (Neodiprion lecontei)

Hard pines such as the jack or red pine are often attacked. Scots pine, eastern white pine, Norway spruce, and tamarack are sometimes attacked. Trees less than 15 feet tall are preferred by this insect

What you will see:

  • Reddish-brown needles that appear straw-like
  • Completely bare branches
  • Heavily infested trees may lose all needles, and some bark

Life cycle:

  • Adults emerge a few weeks into spring
  • Eggs are laid individually in slits at the edge of needles
  • Three to five weeks later, larvae are hatched and begin to feed
  • When they are fully grown, they drop to the ground and form a cocoon to survive the winter
  • Typically, there is only one generation per year

    Cultural Practices:

    • When there is only a small sawfly outbreak, larvae can be dislodged with a strong stream of water. infected needles should be destroyed
    • Avoid planting where the tree will have to compete for nutrients in the soil. A starved tree is a weak, and therefore susceptible, tree.
    • Enhance tree’s growing environment with the Root Enhancement System© include Mature Prescription Organic Matter©
    • Chemical treatments are effective to control this problem insect. Please consult with your Arborist for the best therapies.