More recent entomology questions and answers

Entomology answers

Black widow's red hourglass turns white

I caught a black widow spider and put it in 70 percent alcohol, but the red hourglass turned white. The container is not airtight. Would that have everything to do with it?

It is normal for the red hourglass to turn white when black widows are placed in alcohol and it has nothing to do with the container not being airtight.

The red coloration of the hourglass is the result of biological pigments. These pigments are produced by living cells and so they are not produced when the cells die. This happens to many dead insects or spiders whose coloration comes from pigments. However, pigments are only one form of coloration. Many insects or spiders do not lose certain coloration when they die because colors are also a result of the structure of their exoskeletons. The microstructure of the surface scatters or diffracts light into different wavelengths much like a prism does, and this structure doesn't change when they die, so the coloration persists.

Most insects or spiders have a combination of both pigments and structural color. What you are seeing is a normal change in the hourglass due to the nature of its coloration. If its color were structural it would stay red, but since it changes, we know the red color is due to a pigment.

Richard Houseman
Assistant Professor of Entomology
State Urban Entomology Extension Specialist

Resembles a hummingbird

I have been watching some type of flying thing around my flowers. I thought it was a hummingbird since plenty are around here. However, when I was able to get close to it, I saw it was something else. It's wings were moving just like a hummingbird. It's thorax was black and yellow like a yellowjacket, but rather fuzzy. It's antenna were like a butterfly's, but it doesn't look anything like a butterfly. It gathered pollen with a long tongue like a bee, and it was about three inches long. It had no stinger and wasn't aggresive at all. What could this be?

From your description, one possibility is that you have seen a hummingbird moth, also known as a hawk moth or sphinx moth which can certainly resemble hummingbirds as they fly around flowers.

Simeon Wright
Plant Diagnostic Clinic Coordinator

Protect house from black widows

I just killed a black widow spider in the garage. How do I protect my house from them?

You can protect your house from black widow and other spiders by following these guidelines:

Make sure the building is in good physical condition. Caulk any cracks or crevices around door and window frames, etc. Install proper screening on all openings to reduce entry.
Keep the premises around the home free of debris such as boxes, papers, rocks, lumber piles, etc. Wear protective gloves and clothing when cleaning out cluttered areas. Remove firewood and lumber piles, landscape timbers, stones, etc near the structure.
Mow lawns and grass around the structure regularly to three inches in height and trim back any vegetation in contact with the structure.
Inspect for spider webs regularly and immediately remove them and any round egg sacs with a vacuum cleaner. Seal and dispose of the bag afterwards. You can spray live spiders on the web with aerosol killers before removing the web.

Black widows are known to be common in protected places. Outdoors, they are found among and under stones, wood, hollow stumps, trees, abandoned rodent burrows, shrubbery, and under decks. Some of their favorite places to live include barns, outhouses, henhouses, sheds, meter boxes, behind brick veneer, barrels, and woodpiles. Indoors, they are typically found in little-used areas of the garage, basement, and crawlspaces. They prefer more cluttered areas because of the harborage it provides for their insect prey.

The black widow's venom is a neurotoxin. The female is usually shy, but will be aggressive and attack immediately after laying eggs or when guarding her egg sac. Their initial bite isn't always painful. The only reliable evidence of a bite is the local swelling it causes with two tiny red spots where the fangs entered. The pain from the bite reaches its maximum within one to three hours. Symptoms include fever and elevated blood pressure, profuse sweating, and nausea. There is an antitoxin available. Immediately call a physician or go to an emergency room. Take the spider with you. If treated, bites are rarely fatal except occasionally in small children.

Richard Houseman
Assistant Professor of Entomology
State Urban Entomology Extension Specialist

Ants or not

There are ants, at least I think they are ants, in my house. I got stung by one in my bed. I have seen them outside a lot, in dirt mostly, but the baby ones are coming inside. The adults are about an inch long, they are black with red stripes on the rear, and the adult stingers are about a quarter inch long. They have a shell that almost makes them impossible to kill. What are they, how are they getting in my house and how do I get rid of them? I have a couple of dead ones if you need one.

I am not sure from your description that the insect is an ant. The MU Plant Diagnostic Clinic can identify insects and provide control recommendations. I suggest taking some digital photos and/or collecting a sample of the insects and submitting them to the clinic for identification.

Simeon Wright
Plant Diagnostic Clinic Coordinator

Strange, smooth, brown caterpillar

A couple of days ago in my driveway, I saw this strange, smooth, brown caterpillar with "eye spots." It was less than two inches long and had a light colored underside. I've never seen anything like it. Do you know what it is?

Based on the size of the "eye spots," I suspect it is the larva of a tiger swallowtail butterfly, Papilio glaucus.

Bruce A. Barrett
Associate Professor of Entomology