The very hungry reclassified caterpillar

Posted on July 6, 2020 by missinghenrymitchell

Not, in fact, a tomato hornworm.

Last week I posted about the voracious caterpillars that decimated one of my tomato plants. I theorized, based on as close an identification as I could make, that it was a tomato hornworm, Manduca quinquemaculata.

Made sense. Fat, green guys with white stripes and brown spots? Check. Horns on their rear ends? Check. Munching on tomatoes? Check. My guys’ stripes weren’t as fat as the ones in the photo from the University of Minnesota Extension publication, but perhaps I had juveniles? Maybe after eating my entire plant, the stripes would grow as bloated as the rest of their bodies.

Not so fast. Enter iNaturalist, a fabulous nature-identification app that I’m in love with. Created as a joint project between the California Academy of Sciences and the National Geographic Society, it allows citizens to upload their observations and get critter identifications from other members. The data are shared with databases like the Global Biodiversity Information Facility, so you can feel good about contributing to biodiversity science.

Everyone on the app piled on to correct me. I don’t have tomato hornworms, although my mistake is a common one. I have tobacco hornworms, Manduca sexta. This link shows the differences very clearly. Tomato hornworms have V-shaped stripes and bluish- or black horns on their rear ends. Tobacco hornworms have white diagonal stripes bordered in black, and have red horns on their butts.

White stripes, red horns. Clearly, tobacco hornworms.

Treatment is the same: pick ’em off and feed them to hungry birds. I’m happy to report the sad, naked tomato stalk grew a few new leaves this week, so maybe it will pull through.

Here at MHM, we believe in science, so I wanted to correct the record. 🙂

The very hungry caterpillar

Posted on July 2, 2020 by missinghenrymitchell

Yesterday’s healthy tomato plant reduced today to a stick? Tomato hornworms may be to blame.

What’s new in your garden? In mine, it’s tomato hornworms.

My vegetable garden is in a location where I walk by it virtually every day. One day, my plants were tall and lush. The next day, one looked like this.

Holy cow. It couldn’t have been deer or groundhogs; the garden is fenced off in a way that prevents either of those from invading. A closer look (much closer, because the little rotters are exceptionally well adapted to their dinner of choice) revealed them to be tomato hornworms, Manduca quinquemaculata.

These suckers were, as you can see, the size of an adult thumb after having munched a five-foot-tall tomato plant to the stalk.

tomato hornworm caterpillar manduca quinquemaculata

How to treat tomato hornworms

Being an eco-friendly pest management type, I grabbed a pair of scissors from the kitchen (I will touch a lot of things in the garden, but not these guys) and snipped off the part of the stem where they sat munching away. With a collection bucket in hand, I dropped the stalk remnant and fat caterpillars into it, then collected another three (thankfully, much smaller) ones from adjacent plants. I dropped them in soapy water and disposed of them in the garbage. Alternative control methods include Bt (Bacillus thuringiensis) and insecticidal soap, but using scissors means you don’t have to go out to the store.

Monitor plants several times a week to stop these guys before they decimate your entire tomato planting. (Decimaters…?)

(Lady) Beetlemania

Posted on December 6, 2014 by missinghenrymitchell

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:

Multicolored Asian Lady Beetle: OSU Extension Fact Sheet.
Multicolored Asian Lady Beetle, Pennsylvania State University Extension Fact Sheet.
Adapted from “Multicolored Asian Lady Beetles Inside Houses,” by Waldvogel et al., North Carolina Cooperative Extension Service. For more information, visit http://www.ces.ncsu.edu/depts/ent/notes/Other/goodpest/note107.html

Controlling flea beetles in the fall garden (help wanted)

Posted on September 4, 2014 by missinghenrymitchell

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

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.

Back in action

Posted on January 28, 2013 by missinghenrymitchell

Please pardon my absence last week. My family played “pass the virus” amongst us but we’re all feeling better now. It’s been a brutal winter for many friends around here; I hope you are staying well where you are.

I got the roses sprayed with lime sulfur last Monday; fortunately, it only has to be done once a year (what a smell!). I sprayed the azaleas and viburnums with dormant oil and as I was strolling around, inspecting the troops, I noticed that the boxwoods are looking a bit rough around the edges.

It appears they are infected with boxwood leafminers, which cause the blistered appearance as well as the splotchy spots on the leaves. They overwinter in the leaves (drat!) and emerge in the spring to lay their eggs and start their cycle again.

Not this year! Although I don’t like to use a lot of chemicals in the landscape, I acknowledge that at times they are necessary, and then I use them very carefully, according to the label instructions (friends, more is not better). Between now and mid-April I’ll be doing some research to find out the least toxic option to manage these critters. The damage is pretty significant on a few of the shrubs and I don’t wish the hedge to look as gappy as the resident 7-year-old’s teeth.

Not only do I have leafminers, but I also appear to have mites as well. Mites are very small insects that suck plant sap out of the leaves. Fortunately, they may be controlled by horticultural oil and insecticidal soap.

I’m hoping my observations this winter will help me stay on top of the problem this spring (which, from the forecast, may happen tomorrow). Fingers crossed!