(Lady) Beetlemania

We’re heading into winter—some of us in the US more than others–which means that you may soon find Asian lady beetles (commonly known as lady bugs) on your windows and in your light fixtures. Although they can be a nuisance, and can stink and stain surfaces if they’re crushed, they don’t do any harm. They’re just looking for a slightly protected space to hibernate.

Asian lady beetles. Photo courtesy of University of Minnesota Extension, http://www.extension.umn.edu/garden/insects/find/multicolored-asian-lady-beetles/

The Asian lady beetles are roughly a quarter-inch long, but their appearance varies. Their forewings may be yellow, orange, beige, or bright red. Ten black spots typically decorate each forewing, but it’s not uncommon for the beetles to have fewer spots, faded spots, or no spots at all. In the spring and summer, these lady beetles prey on aphids and scale insects, benefitting home horticultural and commercial agricultural crops alike. Cooling temperatures signal to adult lady beetles that it’s time to find a protected site where they can spend the winter.

There’s A Place

The lady beetles favor warm and sunny sides of buildings, as well as exposed, light-colored buildings, but any protected location offers some appeal. They may move indoors through cracks in weather stripping, or small gaps around window and door casings or through attic and soffit vents.

I’ll Be Back

You may have noticed that beetles frequently pick the same sites to overwinter. Research suggests that the beetles use chemical cues, possibly from beetle feces or attractant pheromones, to locate the particular crevice they want to inhabit, whether that’s in a tree or in your siding. Although they may seem to permanently inhabit, say, your overhead kitchen light fixture, they actually can’t survive for long periods within the centrally-heated rooms of your house. They prefer to shelter in wall voids or semi-insulated spaces. But they become more active on warm days and move towards bright surfaces, like light-colored walls or ceilings, or lighting fixtures or windowsills. That’s when you notice them.

It’s possible that large numbers of beetles may cause air quality problems indoors that could trigger allergies and/or asthmatic reactions. But fortunately for allergy sufferers, this lady beetle does not reproduce indoors. When the warmer temperatures of spring come around, they’ll move outside in search of food. And they don’t eat wood, so they won’t cause structural damage to your house or to your furniture.

Lady beetles clustered in doorframe. Photo courtesy of Iowa State University IPM. http://www.ipm.iastate.edu/ipm/icm/2007/3-26/asianladybeetle.html

If You’ve Got Trouble Here, There, and Everywhere, and Think It’s All Too Much, Remember All Things Must Pass. And I’m Here to Help.

What can you do to control the invasion?

You Can’t Do That

Don’t reach for the pesticides. You’ll waste your money. Pesticides are not very effective at halting beetle invasions. Spraying and fogging can be hazardous to your and your pets’ health, and excessive use may present fire hazards. Biological controls, like tachnid flies, offer limited effectiveness.

Blacklight traps can catch beetles well in some situations. USDA scientists in Georgia developed a trap that uses no insecticide and it catches the beetles alive for future release or disposal. The trap is about 12″ x 24″ and reportedly can be easily assembled or disassembled. Learn how you can build your own blacklight trap following the USDA’s instructions.

She Came In Through the Bathroom Window

The best approach is to exclude the beetles. Seal around windows, doors, siding, and fascia boards with caulk, weather stripping, or foam sealers. Snugly-fitting sweeps or thresholds on exterior doors can prevent beetles from crawling through those gaps. Keep your window screens in good condition and consider adding insect screens to attic and soffit vents. And as a bonus, doing those things will prevent cold air leaking into your house, saving you money on your heating bills and conserving energy.

Some people vacuum up the beetles. If you like this idea, try a tactic recommended by Dr. Susan Jones of The Ohio State University: Insert a knee-high nylon stocking into the vacuum’s extension hose and secure it with a rubber band. Then reattach the hose and vacuum up the insects. The beetles will be trapped inside the stocking. Remove the rubber band and secure it around the open end of the stocking, or simply tie a knot in the end. Take them outdoors to a protected space under a porch, deck, or shed, and let them hibernate there. In the spring, release them into your garden near aphid-infested plants. If the stocking approach is too much trouble, just use your regular vacuum bag, but be sure to remove it promptly and dispose of it outdoors.

 

For more information:

Controlling flea beetles in the fall garden (help wanted)

I didn’t get row cover on my beans in time this spring, and the flea beetles found me.

tired beans

Flea beetle is something of a catch-all term used to describe several species of beetles (not all of the same genera), all of which are tiny (1/16 to 1/10 of an inch long), that live in the soil and cause mayhem in North American gardens. They adore feeding on your vegetable plants, and can reduce a favorite crop to smithereens if not dealt with promptly. One treatment won’t suffice: They can produce four generations or so in a warm-climate growing season. Overwintering adults typically emerge when temperatures hit about 50 degrees (10 C). In recent years, it’s been 50 degrees at Christmas.

Here is my quandary: Their preferred cuisine is cruciferous, which happens to be what I need to get planted soon. Most winters are mild enough here that greens and root crops may be harvested year-round if grown under horticultural fabric, but that means getting seedlings and transplants off to a good start, starting now.

Row covers can be effectively employed to exclude flea beetles from pristine soil, but (clearly) that’s not what I have. Installing row cover where an infestation has already occurred just traps the beetles inside, keeping them safe from predators while they devour your spinach. Row cover must be sealed tightly all the way around to be effective, by the way.

Trap crops come highly recommended. “Plant a crop of mustard greens!” the gardening literature exhorts. Alas, the trap crops are what I want to eat this winter. Kale, collards, mustard greens, broccolini, radishes, tatsoi, arugula. These are the seed packets sitting on my desk, awaiting my decision. I fear that planting a trap crop, even far away (relatively speaking) from the vegetable bed, will only encourage more of the little punks to move in and feast upon everything in sight.

The garden literature also recommends scouting newly planted beds and counting the beetles as they arrive. This presumes the gardener can count insects best differentiated from dirt with a hand lens before they jump to the safety of the earth. Anyone who has brushed against a plant infested with flea beetles has seen a spray of tiny bugs fleeing the scene of the crime. Who can possibly count them in situ? Even if the gardener manages to hunker silently down and get a view of the action, must she hold her breath to avoid disturbing them? What if she needs to sneeze? (It’s fall pollen season, you know.)

Flea Beetle Management for Canola, Rapeseed, and Mustard in the Canadian Northern Great Plains. Graphic by the Government of Saskatchewan.

I don’t want to spray if I can avoid it. I have been known to pull out the neem oil from time to time, but it’s only moderately effective against flea beetles.

What to do, then?

Possible solutions to flea beetle infestation

I’m tempted to try one or a combination of the following. Have you had success with any of these?

1. Diatomaceous earth. DE is a fine powder made of fossilized remains of diatoms, a kind of algae. When used as an insecticide, the powder absorbs components of the waxy coating of insects’ exoskeletons and causes them to dehydrate. It’s critical to obtain food-grade DE for this application to be effective.

2. Interplanting with garlic. Garlic is a moderately effective insect repellant when sprayed on plant surfaces. I have to plant my garlic somewhere; I suppose it may as well go between my rows of kale.

3. Parasitic nematodes. To read about parasitic nematodes is to discover another of Mother Nature’s horror shows. Employing them can be a bit tricky, because the gardener must get the correct kinds of nematodes (families Steinernematidae and Heterorhabditidae, and some species are picky about who they infect); time the application to coincide with a larval stage of the target species; and keep the soil moist, not too hot, and not too cold.  On the plus side, they don’t infect birds or mammals.

Parasitic nematodes. Photo by Penn State University Extension.

Given my warm climate, and extrapolating unscientifically from the graphic above, I guess I might be able to interrupt a larval cycle if I went out tomorrow and applied the nematodes…maybe?

Please send your advice, post-haste.

Dragonfly season

The dragonflies have started making appearances around my garden.

blue dragonfly

A Great Blue Skimmer? (Libellula vibrans) perching on a dead flower stem.

I love watching these graceful insects buzz around my garden. A small pond in my front yard, perhaps three feet long and two feet wide, seems to be enough to attract them by the dozens. I like how this one seemed to cock his head and consider me as I photographed him.

dragonfly in pond

One of my goals for the summer is to learn more about the dragonflies and other insects that visit my garden. I think this one is the Great Blue Skimmer (Libellula vibrans). Lots of these come to visit, and they’re enormous.

I hope they’re eating lots of mosquitoes.

dragonfly profile

 

Hunger games: The joys of aphid-lady beetle IPM

This weekend, as I cleaned up the spent blooms of my bearded iris (Iris germanica), I noticed that one of the leaves was absolutely covered in aphids. I don’t like to use pesticides if I can avoid it, and bearded iris don’t need them. But aphids enjoying my iris will soon find my roses, my tomatoes, and other edibles–and I really don’t want to use pesticides on anything I’m going to eat.

I noticed a ladybug (or more correctly, lady beetle; I think this is Coccinella septempunctata, or seven-spotted lady beetle) on the ground. I gently picked her up and held her to the iris leaf. I hoped she would make like a high school football team at an all-you-can-eat crab legs buffet.

Lady beetle preparing to feast on aphids on Iris germanica.

Lady beetle preparing to feast on aphids on Iris germanica.

Unlike teenage Homo sapiens, lady beetles apparently aren’t a gluttonous species (though hungry adults can apparently eat up to several hundred aphids per day). But they’re no dummies, either, and know to eat when they are presented with easy prey.

I watched with delight as the aphids, acknowledging her presence, migrated down the leaf towards the ground. They’re slow creatures but can move when faced with imminent threat. As the faster aphids began moving away from the ladybug, the ladybug overtook one of their witless chums.

Lady beetle approaching her prey on a twigWatching a ladybug tear into an aphid is as thrilling as any David Attenborough-narrated documentary on life on the African savanna.  She (not that all lady beetles are female; they’re not) seized that aphid and crushed it in her jaws. In just a few seconds, she had eaten the aphid alive.

I didn’t have my camera at the time, so I raced into the house to grab it. Perhaps she had already feasted on other aphids in the garden, because by the time I came back, although I tried to coax her into eating more, she seemed to be full. So she settled down on the leaf to digest her dinner.

Ladybug content post-meal

No, thank you; I’m full. The lady beetle had eaten her fill by the time I came back.

Want to see the horror show for yourself? Here’s a video showing something similar to what I saw.

Something beneficial: Praying mantis

The other evening, I stepped out to purge my pathway of spotted spurge. And as I did a little deadheaing of the Rudbeckias, I noticed something:

praying mantis

A praying mantis.

These are terrific insects to have in the garden. Beyond being fascinating to watch, they eat other insects that are less desirable, such as aphids and grasshoppers. They also eat beneficial insects like lacewings and ladybugs, but as I have far more aphids than lacewings, I feel positive on balance about this fellow’s presence.

praying mantis closeup

Their heads can apparently swivel 180 degrees to watch their prey, and they have a visual range of up to 65 feet. These predatory insects typically eat their prey alive, although if the prey vigorously resists, the mantis will often start with its victim’s head in order to make the meal a bit more relaxing.

I couldn’t discern what this fellow was watching, but I wouldn’t want to be it, whatever it was.

praying mantis recumbent