Posts Tagged ‘predator’

The Milkweed Community

May 13, 2015
Monarch butterfly on common milkweed © Beatriz Moisset

Monarch butterfly on common milkweed
© Beatriz Moisset

The monarch season is coming, and many gardeners throughout the country are getting ready to welcome the arriving butterflies with milkweeds lovingly cultivated in their gardens. They also brace themselves to battle whatever ills may affect the caterpillars. Milkweed bugs and milkweed beetles are seen with hostility. The “dreaded” tachinid flies, and “hated” stink bugs infuriate gardeners even more. Aphids are not welcome. Lady beetles and lacewings generate mixed feelings because they feed on aphids but they are not loath to snack on some monarch eggs or small caterpillars.

Spotted Lady Beetle larva (Coleomegilla maculata) © Beatriz Moisset

Spotted Lady Beetle larva (Coleomegilla maculata)
© Beatriz Moisset

It is important to take a look at entire ecosystems, not just single species as Carole says in “Saving the Monarch Butterfly

“The Monarch Butterfly is in deep trouble, and many passionate organizations have been created to save this single species. But a focus on protecting habitat instead of concentrating on a single species will provide lasting benefits for all species of wildlife and the native plant communities that support them, a far more worthy effort to many environmentalists and wildlife gardeners.”

So, let us take a quick look at some members of the milkweed community. Despite the formidable defenses these plants have, many species have coevolved with them and can use them as food. They incorporate the milkweed toxins and use them to deter their enemies. In turn, many predators have also coevolved and can eat the milkweed eaters. An entire food chain has developed this way.

Large milkweed bug, Oncopeltus fasciatus on common milkweed © Beatriz Moisset

Large milkweed bug, Oncopeltus fasciatus on common milkweed
© Beatriz Moisset

Milkweed longhorn beetles on common milkweed © Beatriz Moisset

Milkweed longhorn beetles on common milkweed
© Beatriz Moisset

Most monarch lovers are familiar with the brightly colored milkweed bugs and milkweed longhorn beetles. Bear in mind that these insects are represented by a fairly large number of species. That is, there are more than just one milkweed bug and one milkweed beetle. A few other beetles also feed on milkweeds, and several moths also do so, among them the tussock moth and the delicate cycnia.

Tussock moth caterpillar © Beatriz Moisset

Tussock moth caterpillar
© Beatriz Moisset

Sooner or later, those who raise monarch caterpillars are bound to meet two insects which will make them unhappy; one is a predator, the spined soldier bug, the other a parasite, the tachinid fly, Lespesia.

The spined soldier bug, Podisus maculiventris, is a good hunter of caterpillars and beetle grubs. It has a sharp beak with which it impales its victims. It injects some saliva which turns the inside of the prey into a smoothie and so it proceeds to drink this nutritious cocktail. The sight of a shriveled monarch caterpillar hanging from the beak of a stink bug causes great distress to the gardener.

Predatory stink bug, Podisus maculiventris on goldenrod. © Beatriz Moisset

Predatory stink bug, Podisus maculiventris on goldenrod.
© Beatriz Moisset

Podisus maculiventris juvenile (nymph) feeding on dogbane caterpillar © Beatriz Moisset

Podisus maculiventris juvenile (nymph) feeding on dogbane caterpillar
© Beatriz Moisset

The tachinid fly mentioned above goes by the name of Lespesia. It lays its eggs on caterpillars of a large number of species. The tiny fly larva digs inside and proceeds to eat its victim until it reaches full size. Then it comes out of the dying caterpillar and dribbles a sticky trail until it drops to the ground. Not a pretty sight.

Tachinid fly, Lespesia © Stephen Luk

Tachinid fly, Lespesia
© Stephen Luk

Tachind fly, Lespesia, Puparium and parasitized tent caterpillar's cocoon © Stephen Luk

Lespesia puparium and parasitized tent caterpillar’s cocoon
© Stephen Luk

Although these two insects on occasion kill some monarchs, we should not hate them. Actually, their diet is so diverse that it includes a number of pests. They are both used as pest controls for this reason and even sold for this purpose. Podisus is known to eat Mexican bean beetles, European corn borers, diamondback moths, corn earworms, beet armyworms, fall armyworms, cabbage loopers, imported cabbage worms, Colorado potato beetles, and velvetbean caterpillars. The tachinid fly is reported to feed on tent caterpillars, armyworms, cutworms and corn earworms.

Nature is far more complicated than it appears at first sight. It may seem paradoxical, but the spined soldier beetle and the Lespesia fly are indirectly the friends of monarchs, because they help cut down on pesticides. Moreover, we must remember that they have coexisted with monarchs for eons without driving them to extinction. The same can be said about the milkweed herbivores –beetles, bugs and moths. They haven’t driven milkweeds to extinction and they are not likely to do so. We are the ones that pose a threat to milkweeds and to monarch butterflies with our pesticides, habitat destruction and introduction of invasive species.

Let saving the pretty butterfly be the portal to saving the entire community, all the creatures that creep and crawl, the ones that jump or fly and even the ones that kill or get killed. Let us embrace the web of life in its totality, with all its beauty and ugliness.

Delicate cycnia © Beatriz Moisset

Delicate cycnia
© Beatriz Moisset

Additional readings
You may find this Flickr album interesting: Milkweed Visitors
More members of the milkweed community
The monarch butterfly as part of the food web: Monarchs and their Enemies

This article first appeared in Native Plants and Wildlife Gardens


Ambush bug

April 30, 2011

Jagged ambush bug

Poor pollinators! They have to contend with dangerous creatures hiding among the petals of the flowers, not just crab spiders but also sinister ambush bugs. The name is well deserved. These bugs are very good at hiding and waiting patiently until a bee, a fly or some other flower visitor comes near. Then, swift as lightning, they impale their victims with their sharp beaks loaded with fast acting venom. In addition to this form of attack, they have powerful spiny, enlarged front legs that spring into action catching the hapless victim. Just like crab spiders they don’t chew their preys, they drink the fluids and drop the dried up husk down when done feeding.

Ambush bug and prey, a large bumble bee

Ambush bugs are usually smaller than many bees and bumble bees, which doesn’t prevent them from catching them. They have a very unusual shape, with protruding, pointy parts. The rear end is wider than the front. The color pattern is broken. All this makes it hard to see their contour and contribute to their camouflage.
The males are considerably smaller than the females. Sometimes they ride on a female, when mating and don’t hesitate to take food from them.

Habitat. Practically all the habitats visited by all the flower visitors mentioned in this guide. Everywhere where there are flowers.

Season. Most common from July to October. In southern states, also found from February to December

Flowers. A vast array of flowers, usually those grouped in clusters likely to attract many visitors; they like flower heads with many florets that makes it easy for them to hide: goldenrod, asters, queen Anne’s lace, sunflowers.

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Crab spider

April 26, 2011

Whitebanded Crab spider on thistle (Misumenoides formosipes)

Not all flower visitors are insects and not all are pollinators. In fact, some are a threat to pollinators. Such is the case of spiders, crab spiders in particular. The name is very appropriate: they look and they move like crabs. They are very adept at hiding between petals and waiting patiently for prey to fall right in their clutches.

Whitebanded Crab spider hiding on goldenrods

They are not very discriminating; any flower visitor will do. Bees of many kinds, as well as flies and butterflies and even beetles fall prey to them. They are capable of overpowering creatures bigger than themselves. With their fangs they inject saliva, rich in enzymes that act the way a strong acid would, dissolving the tissues of the victim. Spiders can’t chew solids, so they take this “soup” instead.

Crab spider and prey, a small bee

A different type of crab spider and honey bee

Female crab spiders come in different colors. Usually they match well the color of the flower where they are hiding.

Goldenrod Crab spider (Misumena vatia)

It is said that they can change coloration if they move to another flower of a different color and that this change takes several days. Males are a lot smaller and have thinner abdomens. They are not seen very often.

Habitat. Sunny fields, gardens.

Season. From April to October. Practically year round in southern states.

Flowers. they prefer flat open flowers, especially in the Asteraceae family. Asters, thistles, sunflowers, goldenrods provide just the right kind of hiding places.

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Grass-carrying wasps

April 11, 2011

Brown-legged Grass-carrier on mountain mint

Grass carrying wasps get their name from their habit to carry long pieces of grass which they use in their nests. If you see a flying stem or blade of grass, look again and you will notice the wasp that is carrying it. They are black, slender and with an incredibly long and thin waist. That is why their other common name is thread-waisted wasps. Their wings have a smoky or violet color.

Grass-carrying Wasp, Isodontia mexicana

They can be as large as ¾”. They make their nests inside hollow tubes, such as twigs or holes in wood. Sometimes they use the tracks of window screens or window frames which they stuff with grass before placing some prey and an egg. There may be a row of similarly prepared cells. There is nothing to be alarmed; these wasps pose no threat to humans and don’t damage your house. They catch katydids or crickets to feed their young, so they are good pest controls.

Habitat. Fields, open areas, grassy areas.

Season. From March to December in most of North America. Most common in July and August.

Flowers. Many kinds of flowers of the aster family, including goldenrods, also fennel, queen Anne’s lace and sedum

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