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Archive for September, 2014

Boxelder bug nymphs

Aaaagh! They’re swarming all over the house! It’s like a scene from an Alfred Hitchcock horror movie! There are masses of them crawling over every screen trying to get in! Many can guess what I’m talking about – STINK BUGS!

Brown marmorated stink bug

Brown marmorated stink bug

The brown marmorated stink bug (Halyomorpha halys) has not only become an annoying invader of our homes but their populations have exploded to the point that they have become a major threat to many agricultural crops including both ornamentals and food crops.

Native to Asia, the brown marmorated stink bug (BMSB) is a relative newcomer to the US being first reported in Pennsylvania in 1998. Since then their numbers and range have slowly increased and they are now found in 30 different US states and are still on the move.

At least, these annoying pests do not bite, sting, suck your blood, or carry diseases that can be transmitted to humans. Thank goodness for small favors!

Stink bugs crawl over the screen

Stink bugs crawl over the screen

Late September and October is the time of year that these nasty pests begin congregating around the windows and doors of our homes seeking a warm place to spend the winter. As I sit here writing this, there is a stink bug flying around our office; crashing into light fixtures, walls, windows…

The sunny weather and unseasonably warm temperatures last Sunday must have rousted them out of their hiding places and encouraged them to start looking for an overwintering site. They were on every window and every door; trying to find any crack or entryway into the cozy, comfort of our house.

In the past few years, we’ve seen a few stink bugs around our house in the fall but never the masses that appeared on Sunday! It was impressive – in a BAD way! It was hard to open the sliding screen door to get to the deck without letting one or two in. Ugh! They were quite determined.

We managed to keep them out mostly. The ones did manage to sneak in provided amusement for the cats for a while until we were able to catch them and toss them out again.

Green stink bugs are also very damaging to vegetable crops.

Green stink bugs are also very
damaging to vegetable crops.

Because this particular species of stink bug is having such an impact on fruit and vegetable crops, a lot of research is being directed towards developing control methods. Some of this research has focused on natural enemies and pheromone traps in addition to chemical controls.

Horned squash bugs, closely related to stink bugs,  swarm on a cucumber vine.

Horned squash bugs, closely related to
stink bugs, swarm on a cucumber vine.

For the time being, exclusion is one of the best preventative measures for controlling populations indoors. Carefully examine the foundation and around windows and doors for cracks and crevices where they can sneak into the house. They will seek out these entry points in an attempt to find overwintering sites. Use caulk and weather stripping to seal any cracks.

 

Luckily our house is fairly tight and unless they sneak in through an open door, few manage to get in. The attic is a different story. I think they can manage to get in up there fairly easily but it’s hard for them to make their way into the rest of the house from the attic.

Boxelder bug nymphs swarm over a statue in the garden

Boxelder bug nymphs swarm over
a statue in the garden

The boxelder bug is another nuisance insect that can invade your home in droves at this time of the year. Like the stink bugs, they are seeking protected overwintering sites and your warm home fits the bill perfectly! I’ve seen swarms of the bright red immature boxelder bugs crawling over concrete statues and the surrounding plants in the Viette gardens at this time of year. I guess the concrete warms up in the sun and they take advantage of this late season warmth the same as they do when they are swarming on the foundation of your house. Creepy!

 

There are several control products available that will kill stink bugs and boxelder bugs on contact. Bonide Household Insect Control kills on contact but also has some residual action that creates a relatively effective barrier around windows, doors, and other areas where these pests might gain entrance to your home. Use according to the label directions.

Brown marmorated stink bug

Stink bugs are super annoying
in the house!

Stink bug traps have also been developed. Some of these traps, like the Bonide Stink Bug Trap and the Rescue Reusable Stink Bug Trap, use pheromones to attract and trap the bugs. The pheromone traps work best in the spring and summer when the stink bugs are seeking mates. Once daytime temperatures drop below 60° in the fall, they don’t work well. At this point, the mating season is over and their attention is focused on finding a place to spend the winter rather than finding a mate.

Traps that use light as an attractant may work better in the fall. The Rescue Stink Bug Trap has an optional light attachment that can be used to attract and trap the stink bugs that have made their way into your home.

I’ve never tried any of these traps but if you have large numbers of stink bugs in your home, they might be worth a try!

If you search online, you can also find other “creative” ways to control stink bugs in your home. Andre prefers the vacuum cleaner but you’d better change the bag afterward!

Until next time – Happy Gardening!

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Blue-winged wasp feeds on a clover flower

I had two different inquiries about this particular wasp last week.

Our nursery field manager, “Bo” asked me about them because he had noticed small groups of black wasps flying low over his lawn when he was mowing.

Just the day before, someone happened to e-mail us a photo of one of the wasps that had been hovering over his lawn. When I showed the picture to Bo, he said, “Yes! That’s exactly what they look like!”

Who are they?

Bo said these particular wasps weren’t aggressive at all. They were just flying low over the grass like they were looking for something. Well, that’s exactly what they were doing – looking for beetle grubs.

A blue-winged wasp feeds on the nectar of a clover flower.

A blue-winged wasp feeds on the nectar
of a clover flower. Photo sent in by Ralph.

These are one of the scoliid wasps; a group of fairly large solitary wasps that lay their eggs on the beetle larvae that feed on and damage the roots of your grass.

This particular wasp is the blue-winged wasp, Scolia dubia. It is fairly common throughout the United States. Finding these guys hovering over your lawn is both a good thing and a bad thing. The bad news is that if you see a lot of them, it means that you probably have a healthy population of white grubs in your lawn. The good news is that these wasps are out to parasitize the grubs and can actually help control them in you lawn.

You see, the female wasps search out these grubs and lay their eggs on them – one egg per grub. They dig into the ground under the grass or follow the tunnels made by the grubs. When they locate a grub, they sting it to paralyze it and then lay a single egg on its body. When the egg hatches, the wasp larva feeds on the grub, eventually killing it. Good wasp!

Female scoliid wasps will lay up to two eggs per day over about a two month period. That translates to a lot of dead grubs. The adults are active from June to October but the peak of their breeding activity seems to be in the mid to late summer, which, not coincidentally, corresponds to the hatch of their preferred hosts; green June beetle and Japanese beetle grubs.

Adult wasp visits a Rudbeckia flower

An adult wasp visits a Rudbeckia flower.
Felix Francis, University of Delaware,
Bugwood.org

As an added benefit, the adult wasps feed on the nectar of many different flowers and so aid in pollination. They aren’t the most important pollinators around but in these days of dwindling bee populations, every little bit helps.

All-in-all, these are pretty useful wasps to have around. They usually won’t sting you unless you happen to be a grub and they can help you by killing some of those damaging white grubs in your lawn. Good biological control without chemicals! In fact, these beneficial wasps have sometimes been brought in and released in areas that have severe grub infestations.

Another beneficial solitary “bee”! Who knew there were so many!

Until next time – Happy Gardening!

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