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

Hoverflies are beneficial insects

As mentioned in an earlier post on this blog, I planted a fairly large plot of buckwheat adjacent to our vegetable garden this spring. The main idea behind planting buckwheat was to provide forage primarily for honeybees and for any other pollinators that might be around to take advantage of it.

As it turns out honeybees are in the minority. When surveying the buckwheat plot, I noticed for every one honeybee I saw there were ten or twenty other pollinators. They included butterflies, small wild bees, small wasps, many kinds of beetles, flies and hoverflies.

Hoverflies are especially good to have in the garden. The adult hoverfly is a very agile flyer able to hover in one spot then zoom away, stop on a dime and hover in place again — they can even fly backwards.  They don’t have teeth or mandibles so they can’t chew or tear into things. Their mouth parts are spongy and are designed to soak up nectar and other liquids as well as picking up small particles such as pollen. That is why they’re so attracted to the buckwheat flowers.

Hoverflies have a superficial resemblance to bees.
Hoverflies have a superficial resemblance to bees.

Hoverfly larvae on the other hand are insectivores that eat small soft-bodied insects. In the garden that means mostly aphids, thrips, leafhoppers and scale. All four of these common garden pests have a stage in their lifecycle when they are soft-bodied.

After mating the adult female hoverfly buzzes around looking for a likely spot to lay her eggs, someplace where her young will have easy access to food. How does she know where the best spot is? Aphids and those other insects get all their nutrition from plant juices. They can only use part of the sugar in plant sap so they excrete the unneeded sugar as a syrupy liquid called “honeydew”. It’s the honeydew that attracts the female hoverfly: where there’s honeydew, there are insects for her young to feed on.

During the larval stage, each individual hoverfly will eat up to 400 aphids and other insects giving it the needed protein to go on to further development.

Since they are such good flyers, it’s very easy for female hoverflies to fly from the buckwheat to our vegetable garden and back again. The habitat that buckwheat provides enables the beneficial insect population to grow much larger than it would otherwise. That is a good lesson about the advantages of encouraging beneficial insects with plants instead of trying to maintain a garden in the middle of a sterile environment like a mowed lawn.

Bob

 

Pruning milkweeds

I saw my first Monarch butterfly several days ago. I know they were here much earlier because I found a caterpillar on my milkweed plants. That means there had to be a female butterfly around before that.

It takes around four days for a Monarch egg to hatch. The caterpillar stage lasts around a week and a half to two weeks. Since my caterpillar was almost fully grown, the female Monarch that laid his eggs arrived nearly two weeks ago. How did she sneak into the yard without me seeing her?

This monarch caterpillar has by now formed a chrysalis.

Most of my milkweed plants are on the verge of blooming. The plants are maturing and the leaves and stems are beginning to stiffen and get tougher in order to hold up the flowers and seed pods. Although female Monarchs will lay eggs on any milkweed, they prefer the more tender leaves toward the top of the plant.

A gardener I know suggested that I cut back my some of my milkweed plants to stimulate new growth and leaves. Theoretically, those new leaves would make my plants more attractive to the butteries than others in the area. I just snipped off the plant just above the existing leaves. That caused some milkweed sap to ooze out of the cut. That sap is poisonous and irritating so make sure you don’t in your eye.

Cutting the milkweed just above the leaves allows secondary leaf buds to sprout and grow.

This is the first time I’ve tried this with milkweeds. I’ll let you know how it turns out.

Bob

Check those plants you moved indoors for scale insects

With Christmas and other hectic, holiday happenings over, now is a good time to check those plants you brought inside for winter.

When potted plants live outside during the summer, they become susceptible to infestations of all kinds of insects. Usually, if they are in reasonably good health they can tolerate a moderate insect attack. And natural predators like lady bugs and lace wings will keep the bad insect population to a minimum. But when plants are moved indoors, they loose the protection of those natural predators which can allow the insect population to grow.

Scale insects are the ones I have the most problem with. When I start to find a sticky coating, called “honeydew”, on the lower leaves, table, nearby furniture or floor, I know that the scale insects are ramping up their feeding. They can get out of hand quickly at that point and do some real damage to the plant– not to mention the mess they make. Honeydew is sometimes mistakenly called “sap” because the plant owner thinks it is the plant leaking sap all over the place. It’s not always easy to spot a scale infestation if you’ve never seen it before.

The brown ovals are the outer shells of the scale insects. The clear substance is honeydew.
The brown ovals are the outer shells of the scale insects. The clear substance is honeydew.

Scale feed by poking their “beak” into the the plant and feeding on the nutrients from the plant juices. Like most other animals, they excrete waste. In this case it is in the form of that sticky, syrupy  honeydew. Honeydew contains a high concentration of sugar. But how and why do scale insects produce so much sticky residue? The answer is that they pick their feeding spot very carefully. If you remember from middle school biology, plants have two basic types of tubes inside. Those that carry water from the roots up into the plant are called xylem. The other tubes that carry nutrients manufactured by the leaves to the rest of the plant are called phloem.

It is the phloem where the scale insects like to poke their beaks. If they pierced a xylem tube by mistake, all they would get is mostly water and some dissolved minerals. The phloem sap contains sugars for energy, proteins for growth and other things necessary to sustain plant and animal life.

The scale can’t use all of the sugar dissolved in the phloem juices so they excrete the excess sugar which then falls all over the immediate area. Since it is primarily sugar, it is water soluble and fairly easy to clean up with a damp cloth. Small plants can be rinsed off in the sink or bathtub.

My citrus trees are way too big to rinse off in the bathtub and too heavy for me to move to the shower. Instead I use a damp cloth — or even my bare fingers– to rub off the scale from the leaves and branches whenever I find them. I find that if I do a few leaves every day, I can usually keep up with the multiplying insect population, especially if I remember to start early. If you wait too long, it can turn into a tedious, frustrating job.

One other by-product of honeydew is sooty mold, a black, powdery mold that grows om the surface of leaves and other surfaces. All of that sugar provides food for sooty-mold fungus which will grow and leave sticky surfaces with an unsightly black film that can rub off onto clothing.

Even though you may feel overwhelmed by the holiday rush, remember your plants, they will thank you for it.

Bob

 

Look for squash bugs on pumpkins and squash

The squash crop is looking pretty good so far but has had its share of problems.

Earlier in the season we were worried about squash vine borers moving in. Now we have a new pest that we need to take care of, squash bugs. A few days ago I spotted a very familiar sight, squash bug eggs. Once you’ve seen them, you’ll have no trouble finding more.

The eggs are small, shiny, metallic-looking usually found on the underside of the leaves. Many egg clusters I’ve seen this year however, are appearing on the top side of the leaf. Usually, the female lays clusters of eggs that follow the outline of the veins of the leaves giving the clusters a roughly triangular shape.

Here's a couple of squash bug egg clusters. Down in the whorl of the leaf is a group of squash bug nymphs.
Down in the whorl of a squash leaf is a group of squash bug nymphs. To the left and right of the nymphs are two small egg clusters.

Squash bugs can do a lot of damage to your vine crops if you are not careful. Several years ago I had nearly half an acre of pumpkins that became infested with squash bugs. We tried battling them with the first line of attack, crushing their eggs whenever we came across them. After crushing literally hundreds of egg masses, it became apparent we were not going to be able to keep up with the insects. We ended up having to resort to applying an insecticide to save the crop.

The eggs hatch about ten days after being laid. The young newly hatched nymphs have a very soft “skin” making them very susceptible to contact insecticides. Spraying the nymph stage is your best chance to control these pests since the adult bugs are very tough and hard to kill.

Bob

Squash vine borer defense

Squash vine borers are one of the most insidious insect pests in the garden. They attack many vine crops in the vegetable garden especially pumpkins, winter squash, summer squash such as zucchini yellow crook neck, and gourds. Sometimes they will infest muskmelons, watermelons and cucumbers. I’ve had many times in squash and only once in cucumbers.

Although the adult stage of the borer is a moth, it doesn’t look like or act like a moth. Unlike most moths it flies during the day. And instead of fluttering around like a moth, it flies quickly, like a wasp.

The female adult lays its eggs on the base of the main vine, the eggs hatch and the baby borer eats its way into the vine and keeps feeding for about four weeks. It’s very possible that our squash and pumpkin vines have borers in them right now even though they are not exhibiting any visible symptoms.

At first it’s easy to confuse borer symptoms with drought. The plants wilt on hot, sunny days then recover overnight. If left alone, eventually the plants suddenly and completely collapse. The most startling symptom of a squash borer infestation is seeing healthy vigorous vines one day then seemingly the next day they are collapsed, wilted and dying.

I would hate to lose my squash vine at this point.
I would hate to lose my squash vine at this point.

You can help your vines minimize borer damage by taking advantage of  vine growth habits. You’ve probably noticed that squash and  other vines sometimes root themselves further away from the base of the plant. Those roots are actually functional and contribute to the vines growth. By encouraging rooting along different places along the vine, you can minimize the damage the borers do since the vine can get still get water and nutrients from the soil because of the extended root system. If the plant had to depend only on the roots at the base, no water would be able to reach those parts of the vine past the area damaged by the borer.

Rooting happens at the nodes.
Rooting happens at the nodes.

Rooting takes place at the nodes of the vine; those swollen spots on the vine from where the leaves grow. To encourage rooting, cover several nodes with a shovelful of garden soil. The secondary roots that form will support the plant even if the primary vine is destroyed by borers.

Bob

Local lacewings in your garden

While inspecting my garden today I ran across some very cool looking structures on the underside of a leaf. I could tell immediately that they were lacewing eggs. The thin stalks, each holding up a tiny white egg on its end, was the giveaway.

Lacewing eggs are held up on tiny stalks about 1/4" to 3/8" tall.
Lacewing eggs are held up on tiny stalks about 1/4″ to 3/8″ tall.

Lacewings are a good ally to have in your war against insect pests because they are a major predator of aphids and other soft-bodied insects like mealy bug, mites and even small, newly hatched caterpillars among others.

It is the larva stage of the lacewing that terrorizes the other small insects, especially aphids.

If left alone, aphids can rapidly overwhelm a plant by sucking the juice out of a plant's leaves and stems.
If left alone, aphids can rapidly overwhelm a plant by sucking the juice out of a plant’s leaves and stems.

Lacewings eat so many aphids that entomologists have nick-named them “aphid lions”. A single lacewing larva can eat over 200 aphids a week. The adult on the other hand, eats only nectar and pollen.

Depending on the weather conditions, the lacewings will stay in the larval stage for about two to three weeks devouring small insects all the while. When the time is right, they then spin a cocoon and emerge five days later as an adult. The adults mate and the females lay their eggs on the underside of a leaf or other sheltered spot. About four or five days later the eggs hatch and the cycle starts over again.

Watch for lacewing eggs on your plants and avoid spraying insecticide when you find them. Let them do their work and they will reward you by building up their population and eating even more insect pests.

Bob