Posts Tagged ‘crab spider’

Bumble bee’s enemies

July 10, 2011

Bombus bimaculatus paralyzed by ambush bug

The life of a pollinator can be quite hazardous. There are plenty of creatures willing to devour one of them, from insects and spiders to birds. In addition to that, there are many parasites and other pathogens. Perhaps the highest mortality comes from the so called parasitoids and cuckoos. Parasitoids behave somewhere between a parasite and a predator; they parasitize the host, feeding on it, and eventually killing it, while predators kill and eat the prey all at once. Cuckoo bees and wasps, just like cuckoo birds take over the nest, lay their eggs and let the workers of the host species take care of the brood. Many cuckoos are related species, mainly other bumble bees; in some cases they mimic the appearance of the host species.

In general, most birds seem to avoid bumble bees; although there are a few species that specialize on bees. Skunks, voles and moles can attack their nests and eat their reserves and grubs. These creatures destroy a good number of nests. There is a story about Darwin saying that the British armies owed a lot to old spinsters. This was his explanation: Old spinsters owned cats which ate field mice. Fewer mice meant that more bumble bee nests survived. In turn, the bumble bees pollinated the alfalfa that fed the cattle that fed the soldiers and kept them strong and healthy. It was just an unproven entertaining hypothesis, but still a nice illustration of the intricate web of life.

Crab spider on thistle

Crab spiders are so called because they look and move like crabs. They are among the most common predators. They build no webs; instead they hide inside blossoms, waiting patiently for prey and ready to pounce on the first flower visitor that comes within reach. They are well camouflaged and are capable of changing their colors if they have to move to another flower.

Ambush bug on multiflora rose blossom

Ambush bugs deserve the name. They sit for long hours, well hidden inside a flower or cluster of small flowers, waiting for flower visitors. Their contour is jagged making it hard to detect them. They are very good at holding still, tucked in between petals. Their front claws look like those of a preying mantis and they have a sharp beak used for stabbing their prey and sucking vital juices. Their venom must be very powerful because they can paralyze a bumble bee twice their size in the blink of an eye.

Conopid fly on common milkweed

Some flies of the Conopidae family parasitize bumble bees. They hang around flowers waiting for bumble bees and lay just one egg in the narrow space between body segments. The egg hatches, the larva gets inside the unfortunate bee and proceeds to feed on its blood, (its real name is hemolymph because it is more similar to lymph than to blood). As it grows it starts eating the tissues, eventually killing the host.

Bee wolf Philanthus gibbosus

Bee wolf wasps attack many types of bees, bumble bees included, and also other insects. They overpower them and take them to their nests to feed their young. They have a very thick, pitted body cover that serves them as armor.

cuckoo bumble bee, Bombus citrinus

Other enemies of bumble bees are bumble bees themselves, the so called cuckoo bumble bees. There are several species of them. They build no colonies, nor have any workers. A queen attacks and subjugates a colony of honest, hard working bumble bees. She usually kills the resident queen and destroys any eggs. Then proceeds to lay eggs of her own which are nurtured by the workers of the host species.

Bumble bees also suffer from many of the pathogens that afflict honey bees, such as mites, fungi, nematode worms, bacteria and viruses. The life of a pollinator is not an easy one.

Bumble bees. Introduction

Beginners Guide to Pollinators and Other Flower Visitors

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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.

Back to guide

Pollinators and other flower visitors. A field guide for young people

March 26, 2011

Insect flower visitors of many sorts

Flowers are visited by a great variety of insects, and some spiders too. Some of these insect visitors are very beneficial to the flower. They carry pollen from flower to flower performing pollination. This is what the plant needs to make seeds and thus make new plants and new flowers.
The list of flower visitors is extremely long and some of the insects are impossible to tell apart by sight only, so this guide doesn’t attempt to cover them all. I will just merely highlight some of the most common flower visitors, in particular those that pollinate flowers. You will be able to recognize some of them or, at least, you will know what group they belong to.

What do pollinators look like?

Insects have three body sections, called head, thorax and abdomen. The head carries the eyes, the mouth parts and antennae. The thorax is made of three segments and carries three pairs of legs and generally either two pairs or only one pair of wings. The abdomen is made of a series of segments.

What kind of pollinating insect is that?

Different groups of insects vary on the shape of the head, thorax and abdomen. Of special importance are the variations on the kinds of wings. Future blog entries will cover four main types of flower visitors: 1. bees and wasps, 2. flies, 3. butterflies and moths and 4. beetles.

Bee, hairy, pollen combs

Wasp, hairless, “wasp waist”

Bees and wasps have two pairs of membranous wings, they look like saran wrap. The main differences between bees and wasps are that wasps usually have a narrow waist (the separation between the thorax and abdomen) and are less hairy than bees. Female bees usually have a means to carry pollen, the so called pollen baskets or pollen combs, either on their back legs or on the underside of their abdomens. Sometimes these baskets are loaded with pollen.

Ants are related to wasps and resemble them in their appearance, but they have no wings. Only queens and males have wings, but they are seldom seen. Ants are also frequent flower visitors. They rarely can pollinate flowers because they don’t fly and are not likely to carry pollen a significant distance.

Fly, two wings, big eyes, very small antennae

Flies  are important pollinators too. Their wings are also membranous, like those of bees and wasps but they have only one pair instead of two. The flies that visit flowers often look like bees or wasps. They lack stingers so they are good mimics that try to fool hungry birds into thinking that they can sting. Some of the ways to tell them apart is by the eyes which are very large and by the short antennae, made of two separate parts. They are usually hairless and the legs are very thin when compared to those of bees.

Butterfly, wings with scales, knobs at end of antennae

Butterflies and moths  have wings covered by very tiny scales. If you touch them some of those scales come off and they look like dust. They have a very long tongue which they use as a drinking straw to sip nectar from flowers. When not in use they keep it rolled up under their chins.

Moth, wings with scales, antennae without knobs

Butterfly’s antennae end in little knobs, while the antennae of moths can either be feathery or like a string, but never with a knob at the end. Butterflies usually fly during the day, while moths fly at night, although a number of them fly during the day. Night flying moths tend to be rather colorless, but those that fly during the day can be as brightly colored as many butterflies.

Beetle, hardened wings

Beetles have two pairs of wings but the first set is modified and hardened into a wing case that covers and protects the second pair of wings.
You only see this second pair when the beetle is flying or getting ready to fly. This second pair is also membranous like those of bees, wasps and flies and they remain folded under the first pair.

Where can you find pollinators?

Field of goldenrods in the fall

Look for pollinators at flowers. The best flowers are native ones. Garden flowers, especially the double ones don’t attract many pollinators, so tulips or fancy roses are not very good for pollinators. Most pollinators are active when it is warm enough, when it isn’t windy and when the sun is shining. There are a few that fly when it is dark and visit night blooming flowers.

Common milkweed, flowers

Some flowers attract many visitors. Two of the best ones are: common milkweed and all the goldenrods.

Common milkweed blooms in June and early July. The plants can grow 6 feet tall. They have large oval leaves and bunch of flowers arranged like a ball. The flowers are pink and emit a very strong sweet scent.

Goldenrod

Goldenrodsbloom in the fall, from September to November, depending on where you live. There are several types of goldenrods; they all have yellow flowers arranged in rods that give the name to the plant. Their scent is not particularly strong but many insects are attracted to it or to the colorful display.

Asters and related flowers attract large numbers of pollinators.

Asters, blooming in the fall

Sunflowers and skipper

These include many daisy-like flowers such as sunflowers, black-eyed Susans, ragworts, cornflowers, as well as some plants which are not native, dandelions and thistles. The above mentioned goldenrods belong to this family, too.

Mountain mint and Queen Anne’s lace are also good attractants of a variety of flower visitors.

Bees
Honey Bee
Bumble Bees
Carpenter Bees
Halictid Bee or Sweat Bee
Mason Bees and Leaf-cutter Bees
Andrenid Bees

Wasps
Potter Wasps and Mason Wasps
Grass-carrying Wasps
Great Golden Digger Wasp
Hornets and Yellowjackets
Paper Wasps

Flies
Flower Flies or Syrphid Flies
Bee Flies
Blowflies. Lucilia

Butterflies
Monarch
Tiger Swallowtail
Hair Streaks
Pieridae Butterflies: Whites and Sulphurs
Silver Spotted Skipper

Moths
Hummingbird Moth
Hawk Moths
Ailanthus Web-worm Moth
Yellow-collared Scape Moth

Beetles
Tumbling Flower Beetles
Flower Long Horn Beetles
Soldier Beetles
Japanese Beetle
Ladybugs or Lady Beetles

Other frequent flower visitors
Ambush Bug
Crab Spider

——————————————–
Further readings
Overview of Orders of Insects
Native bees of North America
Bumble bees

 

You may purchase the electronic version:

Beginners Guide to Pollinators and Other Flower Visitors