Sunday, August 28, 2011

The Carpenter Bee and the Tiger Bee Fly

The eastern carpenter bee is about an inch long, with a shiny black hairless abdomen that distinguishes it from bumblebees. 

It's no coincidence that I find carpenter bees and tiger bee flies in the local park. 

Carpenter bees are solitary bees, which means that they don't live in hives like the social honeybees that we normally picture when we think of bees. They are called carpenter bees because they make tunnels in wood. Typically, a female carpenter bee uses her strong jaws to evacuate a tunnel in weathered unpainted wood. She makes a round hole about one-half inch in diameter, and digs in as deep as ten inches. Then she goes to forage for pollen and nectar. When she returns, she shapes pollen into balls that we call beebread. She places a ball of beebread at the end of the tunnel and lays a single egg on it, and then she seals it off with a wall of chewed wood pulp. She provisions six to ten chambers in a row, each with a single egg and a ball of food. When the eggs hatch into larvae, they eat beebread until they become pupae. 

A carpenter bee near the entrance to a tunnel nest. 

New adults emerge at the end of summer, chewing through the soft chamber walls. They do not mate just then; they feed on pollen and nectar and return to spend a quiet winter in the tunnels. The next spring they come out to mate, and the cycle begins again. There is usually just one generation a year, except in warm southern places. They may make nests in human structures -- sheds, porches, roof overhangs, even outdoor furniture -- but they rarely cause anything more than cosmetic damage except when their nests are expanded extensively through repeated use. 

I often see carpenter bees foraging in the flowers at Brooklyn Bridge Park by the East River in New York City. But what's with this tiger bee fly?

The tiger bee fly, Xenox tigrinus, seems to have more than its share of names. Tiger is for the patterned wings. Fly  because it's a fly. Bee because it preys on bees. 

Tiger bee flies hunt for carpenter bees! When a female tiger bee fly locates a carpenter bee nest she may lay eggs at the entrance. The eggs hatch into larvae that find the carpenter bees within. Tiger bee fly larvae usually wait until their prey is in the helpless pupal state, and then they eat it. Notice that the tiger bee fly in the picture is visiting the kind of untreated unpainted wooden post that carpenter bees like to tunnel in. 

It reminds me of this nursery rhyme: 

Big fleas have little fleas, 
Upon their backs to bite 'em,
And little fleas have lesser fleas, 
And so, ad infinitum.

And the great fleas, themselves, in turn
Have greater fleas to go on;
While these again have greater still,
And greater still, and so on. 

See the light colored patch on this carpenter bee's face? That's how you can tell it's a male -- females don't have that mark. 

Sunday, August 21, 2011

The Japanese beetle and the blue-winged wasp

The rose borders around the amphitheater in Brooklyn Bridge Park are relatively new -- I think they were planted last summer. But already Japanese beetles are abundant there. Japanese beetles love to eat roses. And after a meal of petals they meet and mate.

A Japanese beetle couple in the Brooklyn Bridge Park roses. 
Adult Japanese beetles are shiny metallic green, oval, convex, and about one-half inch long with bronze-colored wings. Five pairs of white hair tufts project from under the wing covers on each side of the body and another pair decorate the rear end of the abdomen.

The Japanese beetle, Popillia japonica. Pretty! 

The first report of Japanese beetles in the United States was from a plant nursery in New Jersey in 1916. The insects quickly spread to the wild and we have been trying to eradicate them ever since. Adult Japanese beetles eat flowers, vegetable crops, fruit trees, and ornamental plants. They are famous for eating the soft flesh of leaves from between the veins and leaving behind leaf skeletons. They eat soft rose petals completely. As if that were not bad enough, the larval stage lives in the soil and eats grass roots, damaging lawns. A Japanese beetle larva is a white worm-like "grub" that is about an inch long at maturity; it has three pairs of tiny legs and a round brown head.

After mating, a female Japanese beetle lays eggs in the soil. She lands on the ground and digs a burrow a few inches deep. She lays a few eggs and then she feeds and lays intermittently until she has ensconced a few dozen eggs in the soil. The eggs hatch into larvae by midsummer. The larvae burrow around underground, eating grass roots. When cold weather comes the larvae dig deep in the soil to spend the winter inactive far below the surface. In spring they burrow back up to root level and eat and eat and eat. After a brief pupal stage they emerge as adults and dig themselves out of the ground.

The Japanese beetle life cycle takes a year. Ten months of that are spent underground. Summer is their time to shine; they have just two adult summer months to fly in the sunlight and eat roses.

But Japanese beetles are not the only insects that have moved into the new park. I found the blue-winged wasp pictured below sipping nectar from goldenrod flowers in the park's water garden. The blue-winged wasp in about an inch long. Its head, antennae, and legs are black. Most of its abdomen is reddish brown. Two bright yellow spots on the upper surface of the abdomen make it easy to identify.

The blue-winged wasp, Scolia dubia
Female blue-winged wasps take breaks from sipping nectar to fly low over grass. They search for beetle grubs. They love Japanese beetles. The wasp burrows into the soil to find them. (Not surprisingly, they are sometimes called digger wasps.) The wasp will sting a captured grub to paralyze it. Then she digs deeper, constructs a little cell, lays an egg right on the unlucky grub, and departs. When the wasp egg hatches into a larva it will feast on the beetle grub its mother left for it. The wasp larva grows, eating grub, and eventually makes a cocoon right inside the grub's corpse where it spends the winter. Ghoulish, eh? The new wasp emerges as an adult in spring or summer, just about when the Japanese beetle grubs are beginning to fatten up.

This is almost enough to make me stop complaining about mosquito bites -- obviously some species have much bigger insect problems!

Blue iridescent reflections give the blue-winged wasp its common name. 

Sunday, August 14, 2011

Honeybee takes a drink!

Call me quirky. I like to watch insects drink from water droplets. I had my camera with me when this honeybee decided to take a drink. Enlarge the photos by clicking on them for a very close look.
The honeybee was finishing off a drop of water when I got there. 
Then it paused while deciding on another. 
It found a nice drop and stuck its proboscis in. 
Just one camera click later and the drop was half its original size. 
On hot days honeybees sometimes spread water on their hives and fan it with their wings for evaporative cooling! 

Sunday, August 7, 2011

The Killdeer

Run, stop, hesitate...head bob. Run, stop, hesitate...head bob. 
The killdeer travels at its own peculiar pace. 

Although the killdeer is technically a shorebird it can be found far from the ocean in fields, parks, parking lots and pastures and on lawns and golf courses. It forages in such places for grasshoppers, snails, beetles, ants, flies, insect larvae, and worms.

Killdeer breed in summer across the United States and Canada. Northern populations migrate south for the cold months. They can be found in the southern states all year. Their winter range includes Central America and northern South America.

Killdeer (the plural can be killdeer or killdeers) get their common name from their loud piercing cries of kill-deer! kill-deer! Their calls are so loud that they have also been called the chattering plovers and noisy plovers.

Males and females look alike and their plumage is essentially the same year round. They are eight to 11 inches long, grayish brown above, and white below. They have reddish feathers on the rump and two black bands on the chest. The tail ends in a white-tipped black band. They have a white stripe above the eyes and a white bar on the face above the beak. Their bold plumage acts as disruptive camouflage, breaking up the body outline and making the bird surprisingly hard to see when it stands still.

Killdeer make nests on open ground with a view all around and usually near water. They are minimalists. Their nests are just little scrapes in the ground that may be lined with pebbles, grass, wood chips, or debris. A scientific study showed that killdeer prefer light colored nesting material; when scientists removed material from killdeer nests and placed white and black sticks nearby as possible replacement material, the birds overwhelmingly selected white sticks. Killdeer usually make nests on light colored backgrounds like oyster shell piles, pale roof gravel, and even the crushed-limestone boundary lines of sports fields. Building on reflective white substrates may help keep their nests cool, which is a problem for them as they nest in the open without shade from the sun.

The eggs are tan with splotches of brown or black and they can be surprisingly hard to see even though they are in plain sight. One naturalist described finding perfectly camouflaged eggs against a background of trash and broken glass on a rubbish pile. Eggs in nests on sandy gravel and on the tarpaper and stone roof of a racetrack grandstand were equally well concealed.

But nesting in the open is still risky. Killdeer have an active strategy when camouflage fails; they pretend to be injured to draw invaders away. The bird crouches with wings drooping and drags its fanned tail on the ground. It appears to have a broken wing. It cries in apparent distress. It may flap its wings against the ground. Facing away from the intruder, the bird looks over its shoulder while walking away. When the strategy works, the intruder follows in pursuit of what appears to be an easy victim. At a distance from the nest, the killdeer drops its pretense and flies away. While all this goes on, the downy chicks, perhaps as large as a human thumb, lay flat and motionless in the nest with necks outstretched -- lying low and hoping for the best.

Killdeer were once hunted for plumes to decorate ladies' hats, and for eggs, and as food. John James Audubon wrote that although killdeer were sold in the markets year round, they were only really good when they were fattened up in autumn. It became illegal to harm killdeer when they came under the protection of the Migratory Bird Treaty Act of 1918.

That's a couple of food and fashion fads that everyone should be glad to see the end of.

The Killdeer, Charadrius vociferus.