Lookalike insect pests

This week while scouting for garden for pests, I came across an interesting coincidence. Two look-alike, but completely unrelated, insect pests showed up at the same time. They were in the same general area but on different plants in nearby gardens.

The first insect I spotted was rose sawfly larvae feeding on the roses. There were quite a few of them and were pretty big by the time I saw them.  They had eaten quite a bit of the foliage. If I hadn’t spotted them, they would have completely defoliated the bushes.

The other insect I came across, just minutes after seeing the sawflies, was cross-striped cabbage worms feeding on some cauliflower plants. It struck me how similar the sawflies and cross-striped caterpillars look. At that stage in their particular lifecycles, they were nearly the same size.

Even though they were each feeding on their preferred food, if you didn’t know better, you could easily confuse the two. However, cross-striped cabbage worms would never be found on roses and like-wise, rose sawflies would turn up their noses at cauliflower.

The sawfly larva at this stage looks like a caterpillar but is not.
The cross-striped caterpillar is a true caterpillar.

Both of these insects eat leaves and the damage they do is quite similar looking too as they both chew holes. That’s where the similarities end. They are unrelated species. The rose sawfly belongs to the wasp family while the cross-striped caterpillar is in the butterfly/moth family (Lepodoptera). About the only thing you can say about them is they are both insects.

That doesn’t make too much difference when it comes to killing them with chemical insecticides, but if you are an organic gardener, it can make a huge difference. For example the biological insecticide Bt (Bacillus thuringensis) infects butterflies and moths so will kill cross-striped caterpillars. But rose sawflies, because they are wasps and not Lepodoptera, are un-phased by Bt spores. They can eat Bt all day long and not be affected in the least.

I see cases of mistaken identity all the time. This is a good example of how easy it is to misidentify something if you’re not careful.

Bob

 

Holes in tomatoes

It seems like it’s been a tougher season than normal for our tomatoes. First they got a late start because of the cold wet spring. Then we had a blast of heat just when they were blooming, causing the flowers to fall off. Now insects are attacking any tomatoes that have made it this far.

In one of my gardens, well over half of my tomatoes have tomato fruit worm damage. This is the same insect that bores into ears of sweet corn and other vegetables.

On tomatoes the damage shows up as holes or depressions that are clearly caused by something eating them. Tomatoes can look fine one day, then bam! holes in them the next. Often the worms tunnel into the fruit and leave behind frass –worm poo — if nothing is done to stop them.

Typical tomato fruit worm damage.

The problem is you can’t find who doing the eating. You might suspect bird pecking or mice bites or even tomato horn worm damage. Tomato fruit worms are hard to find. I saw one today on a plant and by the time I retrieved my phone to take a picture for you it was gone, or at least I couldn’t find it again.

Holes chewed in the tomato fruit are a passageway for fungus to enter potentially causing serious fruit rot. When the holes are new, you can just cut away the damaged portion and still use the rest of the tomato.

About the only way you can control these critters once they found your garden is to spray an insecticide. I prefer to use the biological insecticide BT since it will not harm pollinators. Other insecticides will control them too.

If you are seeing symptoms of tomato fruit worm on your tomatoes, I suggest getting them under control ASAP before they do any more damage.

Bob

Cicada killers on the prowl

A few days ago I noticed a fresh pile of dirt near one of my tomato plants. Looking closer I noticed a hole in the ground next to the pile. I recognized the excavation as that of a cicada killer wasp.

That’s a descriptive, but unimaginative, name for them since they really do kill cicadas. These wasps show up each year shortly after the cicadas arrive during the dog days of summer.

These are big wasps that make a lot of scary buzzing sounds when they fly. Entomologists tell us that they rarely sting even when provoked. Mine were certainly even tempered. But I’m not the one that is going to tell you that they won’t sting you. I seem to remember a few years back some experts telling us that stingrays in the ocean are harmless, but I digress.

I wanted to get a photo of the cicada killer when I first spotted it but it wouldn’t sit still long enough. As soon a I was able to get close enough to focus my phone camera, it would take off with the immobile cicada in tow. A few days later I forgot all about the wasp and was placing some straw around some of the tomato plants to keep the fruit off of the ground. Low and behold, there was a cicada killer, with a cicada, looking for a way to get into her tunnel. A shallow layer of straw slowed her down long enough for me to snap a couple of photos.

The straw slowed down the wasp enough for me to snap a photo of the wasp and her prey.
The straw slowed down the wasp enough for me to snap a photo of the wasp and her prey.
She found her way into the tunnel entrance.
She found her way into the tunnel entrance.

The female wasps are responsible for all the digging we see. They construct tunnels that are between six and 12 inches deep and can be three or four feet long, or even longer. That’s a lot of dirt for one insect to move all by herself. Often there are side rooms in these tunnels.  Not only does the female wasp dig the tunnels, she also does all the hunting for the cicadas. The male is unable to hunt even if he wanted to since he does’t have a stinger. He does help however by scaring away predators.

Once the female finds a likely victim, she plunges her stinger into the cicada, not to kill it mind you, but  just to paralyze it. She wants the cicada to be alive when her offspring eats it. Once the cicada is immobilized, the wasp flips it over so it is face to face with its prey. Even though the cicada can weight more than twice as much as the wasp, she is such a strong flier that she can lift it and fly with it to her tunnel. There she carries it down to one of the rooms and places it there as sustenance for her young. She then uses her stinger, which is actually an ovipositor , to lay an egg in just the right spot of the cicada.

The wasp grub hatches from the egg right away and quickly starts eating the cicada in such a way to keep it alive as long as possible. In a few days, there is nothing left but the hollowed out shell of the cicada. In the meantime, the grub has grown into a full size larva. If the grub is a female, she gets to eat a second cicada.

Once mature, the larva spin a cocoon and pupate underground until next summer when they emerge as an adult wasp. Like many insects, the adult wasp has a different diet than its larval stage eating only tree sap and nectar from flowers. They don’t even take a nibble from the cicadas they kill.

Cicada killers prefer sandy soil with sparse vegetation — that pretty much describes my weed-free tomato patch. Also there needs to be trees nearby with cicadas in them to provide hunting grounds.

Bob

 

Sphinx moth caterpillars

When you spend a lot of time outdoors in the garden, you’re bound to run across some interesting things from time to time.

This week I was working around some grapevines. In one area I was cleaning up neglected rose bush pulling out an assortment of weeds including a small wild grapevine. It was there I found the odd-looking, pink caterpillar of a Achemon sphinx moth munching on grape leaves.

The next day I was moving a few small grapevines from one location to another and found two more caterpillars, one orange and the other green. One was another Achemon the other looked to be a Virginia creeper sphinx moth. They are closely related to each other and both are related to tomato hornworms, as you could probably guess that by the horn on their posterior.

It’s been a few years since I’ve seen these even though there are a lot of grapes in our area. I usually have to travel to another area to see them and that was the cases this week.

A pink caterpillar this size really catches your eye. Here the caterpillar's "horn" has shrunk down to resemble an eye.
A pink caterpillar this size really catches your eye, over two inches long. Here the caterpillar’s “horn” has shrunk down to resemble an eye.

Because they are so big at this stage, they can eat quite a bit but not enough to do any real harm to the grapevines and harvest size is not affected by their feeding either. They will keep eating and get bigger. In a week or two when they are full size, they will burrow into the soil then form a pupa. There they will stay until next summer when they will emerge as a large moth.

The yellow caterpillar was feeding on concord grape leaves.
The second caterpillar was feeding on concord grape leaves.

If left alone they have the potential to overwhelm a vineyard but their numbers are kept in check by parasitic wasps. Those wasps deposit their eggs into the caterpillar’s body where the eggs hatch. The young wasp larvae then feed on the caterpillar and eventually complete their larval stage of life.

Like a lot of moths, they are only active at night sipping nectar from flowers. Although I’ve only seen a few at night, I occasionally have found them in the morning clinging to a walls near a flower garden. One time I even found one inside, it must have flown in when someone open the door.

I ended up moving the caterpillars to an old, well-established grape vine where I knew they couldn’t do any harm. Once they settled down from all the ruckus, they went back to happily munching  leaves as if nothing happened.

Bob

 

Join the International Monarch Monitoring Blitz

By now I’m sure you know we are in danger of losing the monarch butterfly migration in our lifetime. This critical situation was addressed in 2014 when President Obama met with President Pena Nieto of Mexico and Prime Minister Harper of Canada about it. At that meeting they agreed to “to establish a working group to ensure conservation of the monarch butterfly”. Since then much has been done to encourage research into the habits of monarch butterflies. One such result is the establishment of the annual International Monarch Monitoring Blitz.

This is an event that takes place all across the range of the monarch butterfly that spans large parts of  The United States, Mexico and Canada. The purpose is to try to get a count of the number of monarch butterflies during a small window of time. This year the count started July 28th and runs through August 5th.

Scientists are looking for help during the Blitz, they’re asking for “citizen scientists” to step forward and pitch in for the butterfly count.  It’s simple and fun to participate as a citizen scientist, anyone can do it. All you need to do is count the number of monarchs you see in all stages of the insect’s development; egg, larva, chrysalis and adult and make some observations about milkweed plants. Once you’re done, report your findings online at the Monarch Larva Monitoring Project website.

There’s another one! Add him to the tally.

This is only the second year of this international event, so now’s your chance to get started as an amateur researcher. Years from now as the Blitz expands and becomes more well known, you’ll be able to proudly tell your friends you were among the earliest participants.

We’re working on our part of the Blitz right now  and hope you find the time to join in too. It’s a great way to spend some time outdoors while knowing you’re doing something tangible to help save our beloved monarch butteries.

Bob and Judy

Become a bee helper

By now, most people are aware of the declining honeybee population. What is not as well know is wild bees are having the same problems.

Wild bees are important because in many instances they are more efficient at pollinating some crops than are honeybees. They are also highly adapted to pollinating wild flowering plants making them an essential part of our ecosystem.

Some commercial beekeepers make a large part of their income by renting hives of honeybees to farmers who grow valuable food crops. Almonds are one example of a crop that requires honeybees to pollinate large plantations of trees. There are now a new breed of beekeepers who are commercially raising wild species such as alfalfa leaf cutter bees and renting them out to farmers. I guess in that case they’re not wild anymore.

So what can we do to help out out little flying friends? We can plant pollinator friendly plants in the garden. We can be be aware not to spray our fruit trees when wild plants like dandelion or dutch clover are blossoming in the orchard. But not everyone has fruit trees or even has space for a garden. Not everyone has the inclination or desire to become a keeper of honeybees either. Or if they did, they may not have the time or resources to spend on a hive of bees

You can however become a beekeeper of sorts with very little effort. Instead of keeping honeybees, you can provide a home for wild bees. Most species of wild bees are solitary. They do not congregate together to form colonies like honeybees. They never will see their parents or siblings unlike honeybees who are surrounded by thousands of family member all pitching in to raise them.

When an adult female solitary bee looks for a place to lay her eggs, she doesn’t look for a hive. Instead she looks for a sheltered spot where the egg will be safe while it is incubating on its own. This is most often a crack or fissure in a tree or even better, an opening made by some other animal such a a hole left behind from a tree boring insect.

Complete bee houses are available already built. Or you can build your own, bees are not picky.

Small bee houses for these solitary bees are available to those who would like to help out our wild bees. These bee shelters come in an almost endless variety but they all have one design feature in common, holes that mimic natural cavities for female bees to lay their eggs. Some designs are not much more than simple blocks of wood with many holes drilled into them. Others use stacked up hollow stems of bamboo to form the shelters. Sometimes a roof is attached to keep the rain out.

You can make your own or buy these bee houses at garden centers or online. Either way it is an easy way to become a beekeeper or at least a bee helper. Unfortunately, solitary bees don’t make honey, they have no reason to.  On the other hand they don’t sting.

Bob

 

Finding a sphinx moth pupa

Butterflies and moths overwinter in different forms depending on the species. For example, the famous Monarch overwinters as an adult, swallowtails in the chrysalis stage. Other species of moths or butteries spend the winter as as eggs or as pupae.

Earlier this week I was filling up a plant container with growing mix that I had saved from last fall. The mix was stored in a few open trash cans inside the barn. Using an antique coal shovel, I was able to make good  filling transferring the potting soil to the planters. I noticed in one trash can, lying there in the soil mix, was a brown, leathery looking cigar-shaped thing. Looking closer I could see it was a large insect pupa, that of a sphinx moth.

A sphinx moth is the adult stage of the tomato horn worm, those big, ugly, destructive caterpillars we often see chomping away on our tomato plants during the summer.

Sphinx moths are one of those species that overwinter as pupae. As autumn approaches, the huge hornworm caterpillars leave the plant and burrow into the soil to morph into a pupa. Although hornworms are abundant, finding a pupa is relatively rare. That’s because they burrow so deeply. Most rotary tillers only till to the depth of six or seven inches or so. A gardener with a spade may work the soil as deep as eight inches. The hornworm tunnel down to at least a foot, well under the disturbed topsoil layer.

A sphinx moth pupa is not uncommon but is rarely seen.

 

The caterpillar that formed the pupa that I found came from one of two places, it either traveled from the garden and crawled up the side of the trash can into the mix, which is highly unlikely. Or, I missed it when I was emptying the deep planters last fall, which is probably what happened. One of the planters did have a couple of tomato plants in it, that would explain why the hornworm was there in the first place.

The sphinx moth pupa has a kind of “jug handle” structure that contains the moth’s long tongue.

We have a love-hate relationship with these insects. During their caterpillar stage they can be quite destructive, defoliating entire plants sometimes.  As an adult however, they are fascinating. They don’t have much color but they are quite large and at first glance are often mistaken for a humming bird. They act like a hummingbird too as they hover over flower blossoms gathering nectar.

So, I have a decision to make: should I squash the pupa so it won’t develop into a garden pest later in the season, or let it go to emerge as an interesting visitor to the flower garden. What would you do? Let us know in the comment section below.

Bob

Use warm temperatures during January thaw to control insects with water

 

During many winters we have a January thaw. We had a very welcomed warm spell last week and it looks like there will be another warm-up this week too, even though it may not be quite as warm this time around.

I always like to take advantage of those warm mid-winter days to freshen up my house plants and others that I have growing  inside.

Three of my citrus trees, which are about six feet tall including the pot, share space in a southern window in my woodworking area. That means their leaves are often covered in fine sawdust depending on the project I’m working on. I recently finished a project that required quite a bit of sanding which developed a lot of sawdust that settled on the citrus tree leaves.

Last week’s thaw gave me the opportunity to haul out my two wheel hand-truck and wheel out the heavy potted trees out to the driveway. I didn’t need to hose off the plants because of the drenching rain that came later in the day. That rain was all that was needed to get them clean. Since then however, I’ve generated more saw dust and they’re all dusty again.

The good news is that temperatures are predicted to be near 50 degrees F during the next couple of days. That’ll be the the perfect time to wheel them back out and rinse them off again, only this time I’ll have to drag out the hose. Some of my larger house plants are going to get a good outdoor rinsing too.

I rinse my citrus trees every year we have a January thaw. My trees are 17 years old.

This mid-winter rinsing not only washes off dust but even more importantly, it removes many of the small insect and other pests found on indoor plants such as spider mites, mealy bugs and scale. The population of  those types of pests can build up to a damaging level inside a warm, dry winter environment like we have in many Michigan homes this time of year. Rinsing with water knocks back the insect population to a tolerable level.

Mature citrus tree leaves are tough and can handle strong streams of water. Other plants though have more tender leaves which can be bruised by a too vigorous spray from an exuberant gardener — I know, I’ve done it.

If you plan to do a mid-winter rinsing, I suggest you start with a fine spray and increase the pressure if needed.  You’ll have to use your best judgement as you go along. I use a three-hole nozzle that puts out a very fine, yet strong stream of water that knocks off just about everything without damaging leaves. Be sure to spray the under-side of the leaves. That’s where the biggest concentration of pests will be hiding.

Bob

 

 

 

 

 

 

 

New research on potential organic insecticide

While it’s popular to bash seemingly frivolous tax payer funded scientific research, I think most people would agree that a vast majority of research is worth while.

There is some really interesting research happening over at the US Department of Agriculture that may have the potential to spill over into the organic gardening area. A naturally occurring chemical called methyl bromide may turn out to be a safe, effective, natural insecticide suitable for organic growing.

If methyl bromide sounds vaguely familiar, it’s because you’ve probably seen it on a list of food ingredients on the package of one of your favorite foods or beverages. It’s often listed under one of many different names such as methylbenzoate, benzoic acid, methyl ester and others.

Methyl benzoate is found naturally in the flower aromas of daffodils, tuberoses, kalachoe, snapdragons, petunias, and many others. These flowers produce methyl benzoate as part of their fragrance to attract bees and other insects. This substance contributes to the flavor of bananas, cherries, cloves, allspice, mustard, coffee, black tea, dill, kiwi and other plant foods. It’s used in the food industry for its nutty, cherry-like flavor and fruity, flowery scent.

As it turns out, this chemical, when isolated or as part of a formulation, can repel or even kill many insect pests. Plus it leaves no long term residue that can build up on food or in the environment. All of this is still in the early stage of research, but if it turns out that a methyl benzoate formulation is effective, it probably won’t take long for it to gain governmental approval.

Many insect pests are developing resistance to current pesticides this may help to fill the void left by insecticides that are no longer effective. Also, organic insecticides are not always good at killing certain types of pests. If it works, methyl benzoate will be a valuable addition to the organic insecticide arsenal.

As a side note, methyl bromide is scent drug sniffing dogs are looking for. Methyl benzoate is produced when cocaine is exposed to the moisture in the air.

Bob

Large population of painted lady butterflies this year

Just about everyone knows what a monarch butterfly is and its amazing migration to and from Mexico. But not nearly as many people have even heard of a painted lady butterfly; until this year that is. Reports of painted lady butterflies seem to be all over the twittersphere. The most popular one I’ve seen is the weather radar in Colorado picking up a huge swarm of the migrating butterflies.

In a garden that I tend, I’ve been seeing lots of painted ladies during the past week or so. Although there’s many more than normal, they’re not in radar-detecting numbers, that’s for sure. Since it is the middle of October, most of the plants in the garden are done for the season.  There are however, a couple of hundred late-planted zinnias still going strong. That seems to enough to convince the butterflies to stop by the garden to tank-up on zinnia nectar before continuing their journey south. I’ve noticed there is a wide size variation in the ones I’ve been seeing, some are only less than three-quarters the size of the larger ones. Apparently, the larger insects had much better feeding conditions when they were caterpillars than did their smaller companions.

Although not as big as monarchs, painted ladies are one of our larger butterflies

A quick search online shows not much is known about this species compared to the the intensely studied monarch. They’re still figuring out how they find their way south and what triggers them to migrate. Unlike the monarchs that take more than one generation to migrate, the painted ladies make the entire trip as a single adult. They’re often found in their southern range all beat up from the long flight, yet they still search out just the right plants on which to lay their eggs.

All round the country the same thing is happening: a large expansion of the painted lady butterfly population. Some scientists are so impressed by some of the reports that they are comparing this rare event to this summer’s total eclipse. If you don’t want to be left out of what is possibly a once in a lifetime occurrence, find a place that still has a few flowers in bloom and take part in some fun butterfly viewing. You probably won’t see clouds of painted lady butterflies around here but you certainly won’t have to look very hard to find them.

Bob