Extension Logo
Extension Logo
University of Minnesota Extension

Extension is expanding its online education and resources while in-person events and classes are canceled.

Nuisance invaders

Quick facts

Several types of insects can enter homes and buildings during late summer and fall as they look for shelter for the winter.

  • These insects are generally harmless to people and property and do not reproduce indoors.
  • Such insects are called as nuisance or accidental invaders.
  • Birch catkin feeders, hackberry psyllids and western conifer-seed bugs are nuisance invaders.
  • Pesticides are generally not necessary for control of these nuisance invaders.

Nuisance invaders take shelter in wall voids or cracks and spaces around buildings. You may see them emerging indoors during sunny, mild winter weather and again in spring.

You may not notice them during summer when they feed on plants. But, they become more noticeable during fall when people see them on the outside of buildings or indoors.

    How to get rid of nuisance invaders


    If you see any nuisance invaders indoors, remove them by physical means, such as a dustpan or vacuum. Pesticides are not necessary to treat these insects indoors.


    There is no need to treat the exterior of buildings in most cases. These insects go away on their own as weather grows colder.

    Using pesticides

    If necessary, you can spray the exterior of your home with a residual insecticide, such as permethrin, deltamethrin or bifenthrin. Spray around windows and doors.

    CAUTION: Mention of a pesticide or use of a pesticide label is for educational purposes only. Always follow the pesticide label directions attached to the pesticide container you are using. Remember, the label is the law.

    Pest-proof building exterior

    • Seal cracks and spaces around doors, windows, fascia boards and similar places as well as where utility wires and pipes enter buildings.

    • Install storm windows and 18 mesh size screens to keep out psyllids and other small insects.

    • Repair or replace damaged window and door screens along with any damaged screens in roof and soffit vents, or bathroom and kitchen fans.

    • Install door sweeps or thresholds to all exterior entry doors. Install a rubber seal along the bottom of garage doors.

    • Psyllids are attracted to lights at night. Keep outside lighting turned off or install lights, such as yellow lights, that are less attractive to insects.

    If you have hackberry trees in your yard

    • It is not recommended to cut down hackberry trees in your yard to prevent hackberry psyllid problems.

    • You could treat your trees before galls are produced because psyllids will not be killed later in the season.

    • Spray a pesticide such as acephate, when leaves are ½ expanded in the spring.

    • If hackberry trees are common in your neighborhood, psyllids can fly into your yard even after spraying. Take other control measures mentioned above.

    Birch catkin feeders

    Reddish brown insect with clear wings and brown antennae
    Birch catkin feeder

    Birch catkin feeders, are common on birch trees, especially white-barked birch, during August and September.

    Also known as birch catkin bugs, they have been found on azaleas, rhododendrons and some other plants.

    • They feed on the seeds of their host plants and catkins, in the case of birch.
    • These insects do not harm plants and control measures are not necessary in landscapes.

    These insects generally move to the sides of buildings on sunny, warm fall days.

    • Birch catkin feeders do not seek to enter buildings, but can accidentally fly through open windows or hitchhike indoors on clothing or other objects.
    • People usually only see a few birch catkin feeders indoors at a time and those that do get inside do not generally live long.
    • These bugs give off a bad smell when crushed.

      Hackberry psyllids

      A black-brown insect with black and white spots on the wings
      Hackberry psyllid

      Hackberry psyllids, are small insects that cause the galls commonly seen on hackberry leaves. These insects only affect hackberry trees and do not develop on any other plants.

      • Pachypsylla celtidivesicula is responsible for hackberry blister galls on the upper surface of leaves.
      • P. celtidismamma produce hackberry nipple galls on the underside of leaves.

      Psyllids are annoying because of their presence.

      • They can prick exposed skin as they ‘taste test,’ looking for food.
      • Otherwise, they are harmless to people, pets, houseplants, stored products and furnishings.
      • They are attracted to the sunny sides of buildings and enter through cracks and spaces around windows, doors or siding.
      • They are small enough that they can pass through most screens and are especially common around windows.
      • Psyllid numbers vary from year to year.

      Western conifer-seed bugs

      A black-brown insect with long, black legs and brown antennae
      Western conifer-seed bug

      The western conifer-seed bug, is a type of leaf-footed bug.

      • These bugs are common in small numbers in homes during fall as well as winter and spring.
      • They don’t bite or sting and are harmless to people and their property.

      Jeffrey Hahn, Extension entomologist

      Reviewed in 2018

      Share this page:

      © 2020 Regents of the University of Minnesota. All rights reserved. The University of Minnesota is an equal opportunity educator and employer.