Sunday, May 30, 2010

The three lined potato beetle

A pair of three lined potato beetles copulate on a leaf. 

This pair of brightly colored beetles lives in a flower patch on a traffic island by the entrance to the Brooklyn-Queens Expressway under the Brooklyn Bridge on the Brooklyn side. They are three lined potato beetles, Lema trilinea, named for three black lines on their backs and an appetite for potato plants.

Potatoes? Brooklyn? What?

Three lined potato beetles eat other plants in the potato family, including tomatoes, peppers, eggplant, tobacco and petunias. But on Brooklyn streets they usually eat a purple-flowered weed called bittersweet nightshade or Solanum dulcamara. 

 Bittersweet nightshade is an introduced species that is now widespread in North America.  

Like many members of the potato family, bittersweet nightshade makes toxic chemicals in its leaves that deter herbivores. But three lined potato beetles are not deterred; they are actually famous for recycling the plant’s chemicals.

After eating nightshade leaves, three lined potato beetle larvae produce toxic feces that they let pile up on their backs. They carry it around, presenting a messy, distasteful, and toxic deterrent to would-be predators. Enough insects use the feces-on-the-back strategy that there is a technical name for the waste-based defense -- it's called a “fecal shield.”

If you find adult three lined potato beetles on a plant, look around and you will probably find leaves with patches of tiny yellow eggs and others with muddy green larvae munching away at the leaves.

If I were you, I would not touch the larvae.


Sunday, May 23, 2010

Butterfly Attack!

Red Admiral butterflies were patrolling New York City this week. 

They are breeding now. The territorial males defend patches of ground, preferably on sunny ridge tops, patrolling back and forth in rapid erratic flight. When a female passes through the territory, the male rushes up and starts courting.

Encroaching males get chased. Passing insects, pets, and people, get investigated and sometimes they get chased, too. A Red Admiral may fly at you and bat his wings threateningly -- even though you may not notice.

Red Admirals often land on people. It’s a good opportunity to look at their famous “brush feet.” They seem to have just four legs because their front legs – their brush feet -- are tiny and held folded up close to the body. The brush feet are covered with tiny hairs that can sense plant chemicals; females use them to evaluate the suitability of leaves for their eggs. Since the caterpillars will live where she puts the eggs, it is quite an important decision. She usually selects a tasty nettle plant.

Red Admirals are common in summer from Guatemala through northern Canada, from coast to coast. They can’t survive very cold winters, so the northern parts of North America are re-colonized from southern populations every year.

The Red Admiral butterfly, Vanessa atalanta, has a wingspan of about two to three inches. The upper fore wing is black with a bold red stripe across the middle and white spots near the tip. There is a red band on the rear edge of each hind wing.

There is more information about common butterflies in my book, A Field Guide to Urban Wildlife of North America, which will be published by Stackpole Books in spring 2011. 

Sunday, May 16, 2010

A beetle in the bathtub

The spider beetle, Gibbium aequinoctiale.

About once a year, first thing in the morning, I find one of these in my bathtub.

It stands out against the white background. It’s dark red, about one eighth of an inch long, and has a bulbous body, tiny head, and long expressive antennae the same color as its three pairs of legs. It sits in the tub, unexplained. If I touch it, it curls up and plays dead.

It’s a beetle, although it doesn’t fit most people’s mental image of a beetle. There are more than 350,000 kinds of beetles, and they come in lots of shapes and colors. This one looks a little bit like a spider because of its round body, and the long antennae can be easily mistaken for another pair of legs, which would add up to eight -- the number of legs on a spider.

Spider beetles also get misidentified as bedbugs pretty often because of they are the same color. Everyone is always happy to find out they are wrong about that!  Bedbugs are flat, not globe shaped.

Scientists usually report that spider beetles eat “a variety of dead materials of animal and plant origin,” including flour, old wood, seeds, wool, feathers, leather, and fabrics. Spider beetle can be pests of stored food products, and actually will eat almost anything dry, including more appealing sounding things like breakfast cereal, figs, instant soup mix, rye bread, spices, and chocolate powder. 

Hmmm. None of these things are ever found in my bathtub…so why do I always only ever find spider beetles there?

They forage at night, and most of them scurry back to their day resting places before I rise. But about once a year, an errant beetle making its nightly rounds discovers the dark bathroom. They are attracted to moisture. Exploring. Climbing. Oh no! It falls into the tub! It can’t get out! Morning comes, and behold – there is a beetle in the bathtub.

There is more information about spider beetles in my book, A Field Guide to Urban Wildlife of North America, which will be published by Stackpole Books in spring 2011. 

Sunday, May 9, 2010

Chimney swifts return to Northville, NY

Chimney swifts, Chaetura pelagica, lived in North America before Europeans arrived. Before cities. Before factories. Before the proliferation of brick chimneys.

When John James Audubon wrote about the birds in the early 1800's, they were known as American swifts. They lived in hollow trees and other natural shafts, and they were not found west of the Mississippi River.

As America expanded westward consuming forests, natural swift roosting sites declined but chimneys became more abundant. American swifts adapted to man-made structures and became chimney swifts. Their range now extends from the Atlantic coast to the Rocky Mountains. 

These birds are little dynamos. They fly from dawn until dusk, catching insects. They fly fast on slender pointy wings that curve behind them. They are about five inches long, gray to black, with silvery gray throats. They have somewhat stubby bodies and are sometimes described as "flying cigars." Most of us will only ever see them flying. They scoop up drinking water in their beaks while flying low over ponds, puddles, rivers, and lakes. They even snatch up nest material while flying.

Inside chimneys, they perch vertically, clinging to the rough mortar with long claws, stabilized by short stiff tails. Their little nests are made of twigs and stuck to interior walls of chimneys with the swift's sticky glue-like saliva. The nests protrude about two or three inches, like halves of saucers stuck to the wall. Each nest will hold three to seven tiny white eggs.

Like the famous swallows that return to Capistrano on the same day every year, chimney swifts are philopatric. They return from their wintering sites in South America to the same places and close to the same times each year -- close enough to predict the date. Like May 6th, when a flock returns to a particularly scenic chimney in Northville, NY, a village on the northern tip of Great Sacandaga Lake in the Adirondack Mountains.

I joined villagers and visitors to greet the returning birds on May 6th, 2010, in what has become an annual celebration there. It was awesome!

That's the Hubbell Memorial Chimney in the
photo, where the birds roost. It's all that's left of the Hubbell Glove Factory, which burned to the ground in January 1918.

The chimney is on
Second Street, just off Bridge Street.

This year, the school jazz band started performing around 7:00, providing entertainment while we waited for the bi
rds. Cub scout troop 55 made fried dough.

Neighbors milled and chatted.

Kids ran around.

Some even showed up in costume.

As the sun set and the sky began to darken, a few swifts flew high overhead, chittering softly. They always seem to appear out of nowhere and disappear just as suddenly. As evening deepened, groups of swifts swooped lower and closer to the chimney. People pointed. Old-timers said knowingly "they're coming." Around 8:15 a few dozen birds came flashing by, inspiring the children to shriek "THEY'RE COMING! THEY'RE COMING!"

Chittering swifts passed overhead.

But this year, the night of May 6th was unusually cold and windy. Although a few dozen swifts circled and made many close passes, I only saw two dive down the chimney. The next night was warmer, still, and fair. After 8:00, as darkness spread, the swifts came closer and closer, louder and faster.

It was exciting. The birds twittered and chatted, passing over more often, finally staying to circle around the chimney at tremendous speed. Then they whirled and dove head first into the chimney and were gone! Near the end, as birds plummeted from the sky to disappear down the chimney, they gave the illusion of being sucked into the chimney. People often say it looks like they are flowing down a funnel.

They fly so fast that photographing them poses a problem for an amateur like me. The fast flight needs a fast shutter speed. But it's dark, so a slow shutter speed is required to gather enough light. I end up with photos of blurred birds that look a bit like chimney smoke, I think of them as "impressions:"

The chimney swifts may have to change their habits again. Over time our chimneys have evolved from wide open-topped brick stacks to narrow metal-lined shafts with caps over them. Swift nests will not stick to metal. The birds need surfaces that they can grasp, like stone, firebrick, or masonry flue tiles with mortared joints. Although metal chimneys should be capped because animals can become trapped in them, homeowners routinely cover all chimney openings with caps or screens, so even if they are appropriate for swifts, they are not available.

Most people would probably not mind if swifts used their chimneys during summer, especially considering the benefits of having voracious insect-eaters nearby. Attracting chimney swifts requires only keeping the top of the chimney open and the damper closed from March through October (they show up earlier south of New York). It is also a good idea to schedule chimney cleaning for early March, after the fire season but before the birds return.

 One common concern about swifts is that sometimes the begging noise of nestlings can be heard from inside the house. The problem can be ameliorated by making sure the damper is closed and possibly by placing some insulation or foam rubber below it. Anyway, the period when they are loud enough to be heard is usually only for the two weeks just before they leave the nest.

You may find yourself looking forward to the return of your own chimney swifts!

Visit Northville between May 6th and mid-August to see the swifts turn in for the night.

Or try to find the chimney swifts that live near you by contacting a local bird group or nature society.

There is more information about chimney swifts in my book, A Field Guide to Urban Wildlife of North America, which will be published by Stackpole Books in spring 2011.