Sunday, December 13, 2020

Stink, squash and seed bugs: Uninvited pests

According to northern New York homeowners, there are three bug species that refuse to follow the social distancing guidelines. Six-legged interlopers are occupying residences and gardens en masse this holiday season. The purpose of this article is to describe the bugs, and discuss control strategies for each insect. 

Seed bug

The western conifer seed bug Leptoglossus occidentalis Heidemann (Hemiptera: Coreidae) has become an unwanted roommate in many northern New York homes. They reached New York in 1990, and now occupy at least Columbia, Essex, and Greene Counties. Native to the western United States, the pest is debatably considered invasive on the eastern seaboard. Entomologists who view it as an invasive species argue that it deserves the label because it congregates in houses; however, other scientists argue that the western conifer seed bug is a natural member of the North American insect community, that simply expanded its range eastward. It may be a nuisance, but it should not be considered invasive within the United States. The western conifer seed bug’s colonization pattern is not typical for invasive insects, many of which are introduced from other countries. 

Stink bug

The brown marmorated stink bug Halyomorpha halys Stål (Hemiptera: Pentatomidae) is one such invader. This insect arrived in Allentown, Pennsylvania in 1998, on a shipment from either China, Japan, or a similar location. The brown marmorated stink bug has spread throughout the United States and Canada, infesting homes, gardens, and orchards.

Squash bug

The squash bug Anasa tristis De Geer (Hemiptera: Coreidae) represents a third category of problematic insect. Squash bugs can feed on many species of squashes, gourds, and melons. The bug is native to the United States, but when Native Americans began cultivating squash in the region, the bug began attacking the plant, and has been an issue ever since. Squash bugs are typically not home invaders, although they can be a problem on cucurbit plants grown near residences. 


It can be difficult to tell these three pests apart. The squash bug and the western conifer seed bug are members of the family Coreidae, also known as the “leaf-footed bugs.” The two can be differentiated because the western conifer seed bug has a wide section on each of its hind legs. The section is referred to as a “bell-bottom.” Squash bugs do not have this feature. 

Stink bugs are classified in the family Pentatomidae, a name based on the Greek words “penta,” meaning five, and “tomos,” meaning sections. This name was chosen in reference to the five segments of their antennae. The antennae of western conifer seed bugs have four segments.  It will likely require a hand lens to see the segments, so it might be easier to identify the stink bug by observing the large, semi-triangular armored section on their backs. This region is known as a scutellum. The western conifer seed bug and the squash bug have much smaller triangular sections on their dorsal sides. 

Control methods

Proper identification of the pest is necessary, because different methods are used to control the different bugs. Hardware stores sell sprays that effectively kill stink bugs, such as the Terro spray. Pheromone traps are available from Harris Seeds, but they only work in the summer months, when the bug is reproductively active. Regarding the western conifer seed bug, there are currently no registered pesticides for indoor use against this pest. Efforts to control western conifer seed bugs revolve around preventing the infestation through disruption of the insect’s life cycle. 

Adult seed bugs overwinter by entering insulated locations, such as rodent burrows, bird nests, and piles of leafy detritus. Ironically, installing insulation prevents them from entering warm locations, because it seals the gaps that allow them entry. Removing rodent tunnels, old bird nests, and leaf piles can help keep the pest at bay.

The landscape can also be managed to prevent outbreaks of western conifer seed bugs. Areas with lots of conifers act as staging grounds for western conifer seed bug invasions, so homeowners who add these plants to their properties may want to keep an eye out for bugs on their plants. The insect deposits barrel-shaped eggs on conifer needles in May and June, so early summer is the best time to seek and destroy them. 

If prevention is not possible, physical removal of western conifer seed bugs is the only reliable option. When selecting resting places, the western conifer seed bug prefers crevices. Vacuuming them from the crevices is effective, but take heed not to crush the insects, or they may release a foul smell. Panels on the outside of houses may be overwintering sites for the western conifer seed bug. Removal can be labor-intensive, but nature has some assistants ready to help out. 

Natural enemies of the western conifer seed bug can be found in New York. Parasitoid wasps in the families Platygastridae, Encyrtidae, and Eupelmidae, attack the eggs of western conifer seed bugs. These small, black wasps are not harmful to humans. They have been observed attacking eggs laid on pines, so it is possible that different parasitoid complexes exist for the control of western conifer seed bugs on other plants. 

Western conifer seed bugs can be damaging on tree farms. Synthetic pyrethroids have been used to kill seed bugs in Idaho’s conifer farms, but the sprays may also kill the natural enemies. If a grower chooses to spray, they should wait until the seed bug eggs have hatched. The wasps attack the egg stage, so if eggs are present during the spray date, the wasps may be killed. Synthetic pyrethroids are not organic-approved.

Starlings are known to eat adult western conifer seed bugs. These birds are native to Europe, and were brought to New York’s Central Park by Eugene Schieffelin in 1890 and 1891. He wanted to introduce the birds to North America because they were mentioned in the works of Shakespeare. European starlings are considered by some ornithologists to be invasive because they compete with bluebirds and other cavity nesters for space. The fact that these birds can provide some pest control services adds to the controversy surrounding their presence in North America. 

Birds are also known to eat squash bugs. Unfortunately, the bugs are less active as the amount of sunlight drops, so there are fewer opportunities for birds to eat them. The squash bug overwinters outdoors in piles of dead leaves, so removing detritus is the best way to prevent their populations from surviving the cold months. Parasitoid flies can attack this pest, and some varieties of squash can resist the bug. For more information, contact your local Cornell Cooperative Extension office. 

Seed bugs, squash bugs, and stink bugs can be unwelcome visitors. Hopefully, these tips about insulation and detritus removal can help homeowners avoid stinky surprises. Through diligent monitoring and the conservation of natural enemies, perhaps the hemipteran harassment can be averted. 


Related Stories

Shane Foye is an entomologist volunteering with the Cornell Cooperative Extension of Essex County Agriculture Program. Learn more about Shane and the on-farm projects he's working on at the CCE Essex Agriculture page:

9 Responses

  1. Boreas says:

    Worst year yet at my place with WCSB. They seem to have taken the place of the Asian Ladybug in my house.

    Thanks for the article!!

    • Same here, it’s been bad for two years with squash bugs. I ended up scraping all the eggs i could find off the leaves but still ended up with a bunch of them this year.

  2. Susan weber says:

    Thanks for this piece. Wish there was more info on stick bugs, tho, since they’re the ones I have inside, even now in December. What do they eat? Where do they like to live? Are they harmful or just a big nuisance?

    • Boreas says:

      I just pick them up and put them back outside. I don’t know how effective this is. They are harmless, but if you squeeze them or handle them roughly you will find out how they got their name. I have the best luck picking them up by a back leg.

      • drdirt says:

        my exterminator friend says my nearby farmers melons attract the stinkers .,., we have had 3 tough years .,.., my wife smashes them .,.,. I let them drop in my hand and either flush or throw them outside .,., I have used a serious poison in the past, but it stains the siding.

        my grandson calls the squash bugs ‘female stinkbugs’.

      • Susan weber says:

        Thanks…we usually sweep them into our palm and toss them outside. Good to know they are harmless. Perhaps they are food for something….

      • jeep says:

        Yes, pick them up by a back leg,. This happens to be the same method some suggest the best way for smelling Moth Balls!

  3. Michael Glenn says:

    Excellent information.

  4. Pat B says:

    I did some more reading about stink bugs. I’ve found there besides the one described in this article there is another called a predatory stink bug. Here is a link to info on determining the difference between the two varieties.