Douglas-fir Needle Midge (Contarinia pseudotsugae)
GDD Window (base 50): 200-400 (adult emergence)
Overview:
- Larvae reside in the swollen areas of needles
- Often not observed during mid-summer
- Maggot is less than 5 mm in size
- Larvae can be exposed later in the season by opening the swollen area with a sewing needle
- Larvae drop to the ground in November or December and overwinter in the soil under the tree they infested
- Pupation occurs in early spring as soil temperatures increase
- Adults emerge in late April and May
- Adults can create mating clouds before beginning to lay eggs in the new needle growth
- Causes a twisted distortion of the needles, with yellow banding & swollen areas
- Swollen areas turn brown or purple at maturity
- Symptoms mimic the Cooley spruce gall adelgid & some needle cast diseases
- Host plants: Douglas-firs
Management:
Cultural Practices:
- Natural predators: parasitoids (Platygaster and Gastancistrus parasitic wasps)
- Plant varieties with a delayed bud break
- Increase tree diversity
- Remove heavily infested trees
- Prune heavily infested branches
Materials:
- Contact insecticides:
- Pyrethroids [3A]: -thrins
- Systemic insecticides:
- Organophosphates [1B]: Acephate
- Considerations:
- Can harm non-target species
- Determine best treatment window using traps
- Traps should be placed before late April
- Detection traps can be made with an upside-down plastic recycling bin
- Cut a hole in the side of a box to fit a clear empty jar inside
- Place a dry, crumpled paper towel in the jar to absorb moisture
- Emerging adults will be attracted to the light coming from the jar
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Photo: Sandy Gardosik, PA Dept. of Ag
- Control sprays should be made within one week of the first catch
- Additional sprays can be made after 10 days
Disclaimer – Materials do not cover all possible control scenarios and are intended for licensed professionals. Tradenames do not imply endorsement and are used as examples. You must strictly follow the label for each compound prior to use. Rutgers is not responsible form is used materials or damages thereof. The label is the law. Labels will provide detailed information on use and restrictions. Additionally, application intervals, compatibility, surfactant use, PHI, PPE, important and other key information is described in detail. Always discuss treatments with your local agents. Note: Neonicotinoids can only be legally applied in commercial agriculture settings by licensed applicators. Guidelines and recommendations made in this presentation are specific to the state of New Jersey.