Don’t plant host plants next to my house? Why not?

It’s our instinct to plant beautiful host plants next to our house. In reality, it is best to plant them 20′ and more away from the foundation. If your house is on a slope, plant host plants uphill, not downhill.

Aquatic milkweed – Asclepias perennis

Too often people end up with an insect that is causing problems, such as termites, roaches, or ants. When the house and/or foundation is treated, the insecticide can travel laterally though the soil 15′ and more. The insecticide will then be absorbed by the host plant’s roots and the plant will become deadly to our caterpillars.

If we plant downhill, a good rain or irrigation will wash the insecticide down the slope to the roots of host plants, causing them to become deadly to caterpillars.

A Queen caterpillars eats a leaf of Charlotte’s Blush variegated milkweed

When we had termites in our walls, we caught it in time. Our foundation now must be treated every year but our house did not need to be tented. Each time, ant beds within 15′ of the house are soon covered with a thick layer of dead ants. Two months after treatment, I mistakenly used cudweed growing next to the house to feed American Lady caterpillars. Every one died.

Because we live in north Florida with sandy soil, we are able to have our house treated in late fall, after butterflies quit laying eggs. By spring, when butterflies begin laying eggs again, the insecticide is washed away. In the north or where soil has a good deal of clay or loam, this may not be an option. We no longer plant host plants near our house, even though we changed treatment time to late fall. It just isn’t safe enough for butterflies.

No neonicotinoids?

Does that mean the plant is safe for caterpillars? Absolutely not.

People are excited when nurseries stop using neonicotinoid pesticides. Of course! It’s a good thing. The question is whether we remember that neonicotinoids are only ONE grouping of pesticides. There are many pesticides that are not neonicotinoids.

neonicotinoid label
neonicotinoid label

Two plants can be grown exactly the same, next to each other, one treated with neonicotinoids and the other with a non-neonicotinoid pesticide. Caterpillars eating either plant will be just as dead.

Remember, the fact that a plant isn’t treated with neonicotinoids doesn’t mean it is safe for caterpillars.

Mosquito/insect spraying means …

When the mosquito fogging/spraying truck comes down your road or your neighbor sprays in his yard, what does that mean for your butterfly/pollinator garden? It can mean disaster. Or it may not affect your host plants at all.

Part of what determines the effect it has on your plants depends on several factors.

  1. Type of pesticide: what are the active ingredients?
  2. Is it a systemic or non-systemic pesticide?
  3. Where are your host plants located?
  1. Pesticides cause different symptoms in caterpillars, depending on the active ingredient. Whether it is organic or not doesn’t make a difference. Organic pesticides are as deadly as inorganic pesticides. What matters is the mode of action of the ingredient. Does it affect the nervous system, growth changes, or something else? As homeowners, we have no voice in the pesticide that is used. So, even if we know how it would affect our caterpillars, that bit of knowledge can’t actually help us at all.
  2. Is the pesticide non-systemic (lasts only a few days) or systemic (lasts for months)? If it is non-systemic, covering our plants before the fogging/spraying happens can help if we wait a good 9 hours before removing the covering. If it is systemic, it can be washed into the soil and the plant draw it up into its system. If systemic pesticides are used near you, growing host plants in pots placed on saucers can help. This prevents water from reaching the roots as it flows across your yard.
  3. Where are your host plants located? This is the area where you have greatest control. If your host plants are close to the road, where a fogging truck passes, you will see more deaths after the county fogs for mosquitoes. If your host plants are close to your neighbor’s yard, it would be easy for over-spray or wash to reach your plants. By planting your host plants away from the road and your neighbor’s property, you gain a great deal of control. Over-spray won’t reach very far except on windy days. Rain or irrigation water can wash the spray over into your lawn. Planting uphill from your neighbor, if possible, offers additional protection.

As we talk about pesticides, I want to again mention that those of us who must have our houses treated for termites, we should either plant at least 15′ away from the house foundation or plan treatments at the end of the growing season, about the time of your first hard freeze. For some of the US, this means that the systemic pesticide has time to work out of the plants before the last freeze and plants are growing again. (For the northern states, pesticide may take longer to work out of the soil. It is possible that termite treatment is not available just before the first hard freeze. If it is not, planting host plants away from the foundation may be your only option.)

There are some cities and counties that have caring people in the right job. A nice, polite, and short letter or visit may do a great deal of good. Some counties will avoid spraying in front of a house where someone has asked for their property not to be treated. Rudeness and anger rarely bring the desired results, so politeness and education is the key.

Remember, if your caterpillars have been exposed to pesticide, you can try saving them. This does not work with all pesticides, only a few.

One of the wonder advantages of living in a city or subdivision is that there are neighbors to help when we need help. One of the disadvantages is that if they are too close, many things that they do will affect us.

Bright green liquid that stays green after five minutes is a sign of pesticide exposure.
Bright green liquid that stays green after five minutes is a sign of pesticide exposure. (Photo by Lorena Popelka)

Monarch butterflies are genetically the same in both the eastern and western sides of the United States.

Although it was believed for years that Monarch butterflies in the eastern US and the western US were genetically different, DNA studies have proven that they are the same.

Monarch butterflies overwintering in Mexico
Monarch butterflies overwintering in Mexico

There are two groups simply because they do not naturally fly over the Rocky Mountain Range as they migrate and fly about to mate and lay eggs. The western Monarch butterflies usually stay west and the eastern Monarchs usually stay east. Although Monarch butterflies have been seen in the Rocky Mountains, in high altitudes, it is not their natural flight direction. Unless they are migrating, they seek out milkweed and nectar plants, males searching for female butterflies which are often around milkweed and nectar plants.

Monarchs overwintering at Norma Gibbs Butterfly Park in Huntington, CA
Monarchs overwintering at Norma Gibbs Butterfly Park in Huntington, CA

The practice of tagging and releasing Monarch butterflies has revealed a fact that was not expected. First, some western Monarchs will migrate to Mexico. They are tagged in the west, wild Monarchs, and the tags are found in Mexico.

Second, it was discovered that if a Monarch raised west of the Rocky Mountains is moved to the Eastern US and released, it will migrate to Mexico and vice versa.

Migration destination depends on where it is located when it begins migration, not where it was when it emerged as an adult butterfly. Its DNA signals it what to do depending on its location at the current time and which direction to fly, depending on where it is when it is captured, tagged, and re-released.

This map is a Monarch Watch map, the information based on recovery of tagged Monarch butterflies.

Monarch Watch's Fall Migration Map
Monarch Watch’s Fall Migration Map reveals that some western Monarch butterflies migrate to Mexico.

Dr. Tom Emmel, University of Florida, believed that some Monarchs fly down Florida to Cuba to stay in mountains there. Some, after arriving in Cuba, he believed would fly to the Yucatan Peninsula and over to the overwintering sites in Mexico.

Although the genetics are the same in both eastern and western Monarch butterflies, the USDA does not permit them to be shipped across the continental divide.

Mia Munson provided this link to a Monarch Watch webpage that mentions the DNA study.

IS it eating the plant?

Quite often people will ask why a caterpillar that is known for hosting on one plant is eating a different one. Even today, people are discovering new host plants for species. Some eat it only in captivity and others eat it in the wild. But the question we first must ask is, “IS it eating the plant?” Quite often, it isn’t eating it at all.

Caterpillars move off a host plant for several reasons. Some move off to molt, to pupate, or simply are lost, working their way back to their host plant.

A Gulf Fritillary caterpillar molts on a Bahia grass seed stalk
A Gulf Fritillary caterpillar molts on a Bahia grass seed stalk

We’ve seen many species of caterpillars on plants that weren’t their host plants. Almost every time, they were molting or pupating.

A Zebra Longwing pupates on a marigold bloom
A Zebra Longwing pupates on a marigold bloom

Much to our amazement, we found a Buckeye chrysalis on a snail. You never know where they will choose to pupate.

A Buckeye pupated on a snail
A Buckeye pupated on a snail

We had Buckeye butterflies in a screened garden room. To my surprise, they stripped a butterfly bush (Buddleia davidii) of leaves, pupated, and emerged with no problem. Later we found caterpillars on butterfly bush in the wild. Evidently it happens but rarely.

Buckeye caterpillars eating butterfly bush
Buckeye caterpillars eating butterfly bush

Although there was no question whether the Buckeye caterpillars were eating butterfly bush leaves, we did tests, feeding that particular bush to caterpillars in captivity. They ate it with no problem. We tried another butterfly bush, one that bloomed a different color, and they all died. We bought the lavender blooming bush from a nursery without a label. When we returned to the nursery, they had no idea which cultivar it was.

Monarch butterflies often pupate on milkweed. They also often pupate off milkweed.

A Monarch caterpillar pupate on a pipevine leaf (1/3 way down on the right side of the photo)
A Monarch caterpillar pupate on a pipevine leaf (1/3 way down on the right side of the photo)

Why would a caterpillar eat another or a chrysalis?

Sometimes a caterpillar eats eggs, another caterpillar, a pre-pupa, or a chrysalis, even when there is enough food. Why?

A monarch caterpillar eating a pre-pupa

When we stop to think about it, we realize that an caterpillar is simply a mature egg plus host plant. A pre-pupa is addition of time and more host plant. A chrysalis is the addition of … you get the idea.

Because a caterpillar, pre-pupa, and chrysalis are made entirely of the host plant, so to speak, the taste of the insect would be tasty to caterpillars that eat the same host plant, whether they are the same species or not. We know that some caterpillars that eat distasteful plants are distasteful to many predators. The taste of the host plant controls the taste of the insect.

An egg about to hatch was eaten by a caterpillar, leaving the head of the caterpillar. Another egg has been hollowed out.

The instinct of some species of caterpillars, when they hatch, is to eat its egg shell. Once that shell is eaten, if there is another egg nearby, that instinct may cause it to continue eating eggs.

A painted lady caterpillar had eaten half another caterpillar. (At the time it began eating the other caterpillar, there was food in the container. They were moved for the photo.)

Although it happens more often when caterpillars are contained and run out of food, cannibalism happens even when there is plenty of food available.

Cloudless sulphur caterpillars are well known for cannibalism, out in nature. Even on a large host plant, they often attack and eat other caterpillars. They are one species that are often raised separately, one per plant stem.

Pipevine swallowtails and gold rim (polydamas) swallowtails are extremely cannibalistic in captivity. Once they are near pupation, many farmers raise them separately. As young caterpillars, they are gregarious, staying together on a leaf. Once they grow to three or four instars, they naturally separate on the plant.

Pipevine swallowtail caterpillars are gregarious.

To be safe, simply make sure they have plenty of food and learn which species tend to cannibalize in captivity. Separate them at the appropriate age.

Spring has sprung!

In parts of the world, it is now spring and gardens are growing.  Butterflies are flying, laying eggs, caterpillars are eating, and warm weather is the new normal.

We’ve weeded most of our garden and mulch was spread Saturday.  Although there isn’t much bloom yet, there is enough for butterflies to enjoy the garden.  Quite a bit of the garden still needs to be weeded.

(All photos are from previous years.)

Persimmon tree
Persimmon tree for us and for the butterflies that like fruit

We fenced in the garden, 150’x150′, with 7′ tall fencing because of deer.  They eat so many of our plants.  In the garden we grow fruit trees, vegetables, but primarily butterfly host and nectar plants.

Our garden: a photo from a previous year
Our garden: a photo from a previous year

I haven’t seen a hummingbird yet but I did hear one as I worked near the flowering bottlebrush shrubs.  We normally have hummingbirds in the garden every day, enjoying some of the same nectar plants that long-proboscis butterflies enjoy.

Hummingbird with salvia
Hummingbird with salvia

A hummingbird tries to drink from an ornamental flower

Eggs and/or caterpillars are beginning to appear on our property:

  • Cloudless sulphur on cassia
  • Spicebush swallowtail eggs on camphor tree
  • Gulf fritillary eggs and caterpillars on passion vine, both maypop and Lady Margaret
  • Red admiral eggs and caterpillars on pellitory
  • American lady caterpillars in cudweed, which we specifically leave growing in the garden when it appears
  • Pipevine eggs on the tiny native Virginia snakeroot
  • Giant swallowtail eggs on Hercules’ club

This year we’re planting even more passion vine, more pipevine, more hollyhock (for tropical checkered white butterflies), and of course, more milkweed.  We haven’t had monarch eggs or caterpillars in the garden yet.

The flowering portion of the garden
The flowering portion of the garden

Now that it is spring, what are your plans for this year’s butterfly garden?  Please let us know in the comments below.