Scary specimens!

I don't know about you, but I still get a big kick out of Halloween. I like all of the pumpkins and candy and decorations, and the crisp feeling in the air - especially today after that cold front! Anyway, over the years I've noticed that one little invertebrate seems to be featured around this time of year in various decorations - the black widow spider.

Most people are very familiar with the black widow spider (genus Lactrodectus). They're easy to spot, and it's hard to mistake them for something else - most of the time. More than likely, if you live in the United States, you're quite familiar with this gal here: 

http://en.wikipedia.org/wiki/File:Black_Widow_11-06.jpg

Beautiful, isn't she? Black widows are certainly very striking spiders. Here is a great close-up picture of her hourglass marking. It serves as a warning, saying "Danger! Do not mess with me."

http://en.wikipedia.org/wiki/File:Blackwidow_macro.jpg

Female black widows are the ones that are particularly dangerous to humans, as her bite contains much more neurotoxin than that of a male black widow. Black widow bites can cause severe pain and cramps in humans. In rare cases it can be fatal, but more than likely the bite just leads to a very unpleasant experience.  

Male black widows look much different than females. They are usually more of a brown color, but also have some white and orange coloration as well. They're smaller than females, and sometimes have the unfortunate fate of being snacked on by the female after mating. They are not dangerous to humans. Below is a picture of a brown widow - unfortunately I could not find a usable male black widow photo. I think that they look similar in to this brown widow, both in coloration and body structure, except for the hourglass - males don't seem to have those.

http://en.wikipedia.org/wiki/File:Brown_widow_spider_Latrodectus_geometricus_underside.jpg

Black widows tend to have very tough and sticky webs, and they look chaotic and somewhat half-hazard. When we think of spider webs, we usually think of round, intricate webs that have a pattern. Not so with black widow webs. If you see a web like this outside, stay away. Black widows will leave you alone if you leave them alone. 

We do have some black widows in our collection. Something that I've noticed is that when they are kept in ethanol, their red hourglass turns white or sometimes even a chartreuse color. 

This spider is in a large jar of spiders in the black widow family, Theridiidae. You can just barely see the hourglass that has turned white from the ethanol preservation. The spider is upside down, with the abdomen facing up towards the top left of the vial. 

Happy Halloween, everyone!

Mini Urban Zoo

      Over the last one hundred or so years of human civilization there has been a dramatic shift from people living primarily in rural areas, where agriculture and other primary resource generating activities occur, to living in urban areas such as cities. It was estimated that in 2007 the majority of the world's people would be living in urban centers (McKinney, 2002). What this means is that more people that ever are living in altered urban environments and farther away from native wildlife and plants, so getting out and finding nature can be a bit more difficult. However, compared to other animal groups, insects are a bit easier to find for even a little dose of nature.
     When I moved to Oklahoma to start my job here at the Sam Noble Museum, I rented a tiny apartment not far from the museum. There is a field behind the museum that was left to return to a prairie environment, but the area around my apartment complex proper was far from natural. It was mowed, sprayed, chopped, and otherwise a very neat landscaping job. When I poked around the little yard I had behind my apartment, I wasn't expecting to find much in the way of bugs or plants.
      However, come later that summer, I saw a plant start to crop up in the back area of my yard. Looking closely at the flowers, I noticed it was a monocot (one of the two major groups of plants) and that there was stuff feeding on it. Excitedly I started looking more closely at it, trying to figure out what plant it was, hoping it was a native plant.

Commelina communis, image from wikipedia.com

    I took a plant sample (traditionally botanists take as much of the plant as they can, including the flowers and roots if possible, to identify it), and sat down with my botany book to figure out what it was. It is Commelina communis, or the Asiatic dayflower. And...found out its an invasive, non-native plant from China. Sigh. Its still pretty.
    My second thought was "well, even if the plant isn't native to Oklahoma, maybe the bugs that are feeding on it are!". Many native species of insects have successfully "switched over" to feeding on plants not originally from North America. This includes feeding on things like apple, corn, and other crops produced for food as well as landscaping plants (bushes, ornamental trees). Maybe what was munching on the plant switched too. So, sitting next to the plant one afternoon in the sun with a container to put the bugs in, I caught two things that were feeding on the plant.
     First, I found this beetle.

Criocoris sp. Sorry for the fuzzy image, still figuring out my new camera!

     The beetle is part of the Chrysomelidae family, or the Leaf Beetles. These beetles primarily feed on plants, and usually on one or two types of plants only for each species. This particular beetle, a member of the Criocoris genus, feeds mostly on asparagus (hence its common name, asparagus beetle). They are native to Europe and Asia, where asparagus is also from, and were likely brought over when we brought the plant to farm and eat here in North America. And what is interesting is that not only was little guy not feeding on the non-native asparagus, but instead switched to the non-native dayflower. Both plants are part of the monocot group, so it was a relatively similar group of plants to switch to.
     The second thing I found was this bug:

Sixeonotus sp.

   These bugs, which are members of the Miridae family (or, Plant bugs). They are part of a subfamily of bugs called the Bryocorinae, which primarily feed on ferns and monocots. Because Commelina is a monocot, these guys also seemed to switch over to feeding on that plant versus our native Oklahoma monocot plants. However, unlike Criocoris, with Sixeonotus I finally found a native Oklahoman bug, since these bugs are found in North America. I was really happy to find a native Oklahoma bug, even in my highly maintained apartment complex back yard!
     So, in short, even in modified urban habitats where you have a lot of non-native plants and insects, if you look close enough you still can find a little native Oklahoma sneaking in and persisting. Next time you are in your back yard, even in one as small as one like mine, take a closer look at what is there. You may have your own little patch of nature ready to be explored!

To fly or not to fly

   One of the first, and maybe the biggest advantages invertebrates have over vertebrates, is their ability to fly. Primitive insects were the first animals on earth to fly: before dinosaurs, before birds, before bats. There are many different hypotheses about how flight evolved in insects and it remains a contentious subject. However, once insects did evolve the ability to fly, they were able to take over an environment no other animal had laid claim on. And they soon dominated it.

Some Pepsis wasps, showing off their large orange-colored wings

 Once insects were able to fly, they were able to move across large areas very quickly in search of food, new habitats, and mates. If the water dried up in a pond, they could fly to another one. If the plant they were feeding on lost most of its nutrition, they could fly off to find a new plant. Until dinosaurs, birds and bats evolved, the only other predators insects had to worry about were other insects. Many insects got very large earlier in Earth's history, with some species related to dragonflies getting as large as 6 feet in diameter, wing-tip to wing tip (Meganeura)!
    So, with all of the benefits of flying and having wings, why would a grasshopper, like the ones in the family Romaleidae (Lubber grasshoppers) have evolved to have small, nearly non-functional wings?

Brachystola sp. Lubber grasshopper found at Black Mesa, Oklahoma

   Well, its because having wings can be "expensive" for the body. Being able to fly requires large amounts of muscle tissue to be able to bend, twist, and move the wings. Especially for insects, which have a hard exoskeleton they have to pull and push like plates. This requires a lot of protein, energy to fuel the muscles, and weight.
    In many cases where the cost to the insect's body to maintain the muscles and wings is higher than the cost without them for finding food, a mate, or escaping predators, some insects have evolved to put those resources and energy to other structures as part of a "trade off". For insects such as grasshoppers, which spend most of their time munching on plants as herbivores to extract the nutrients from the grasses and other plants (think of them as the cows of the insect world of sorts), it may be better to not have wings if you aren't going to use them. Especially since grasshoppers have another formidable way to get away and disperse...they can jump really well! If investing more in their legs to jump is better than the wings, then evolution will likely push the grasshoppers to bigger legs and smaller wings. Check out how big the hind legs are on the grasshopper above!
     So, while most insects still fly and fly very well, there are a few insects that took the route less traveled and are now sticking to the ground again. If you are looking for insects, don't forget to look down as well as up!

Creating a stink about Stink Bugs

This weekend I will be attending the annual Oklahoma Bioblitz, which is held every fall at a different location in the state to count as many species as possible in a 24hr period. This year's meeting is in Foss State Park in Oklahoma, which is in the Western-Central area of the state. My duties at this year's meeting will be the Invertebrate Team leader (which means I keep track of how many species we find), and the resident expert on Heteroptera (true bugs).
   One of the most common bugs I usually run into on Bioblitzes here in Oklahoma are stink bugs. Stink bugs are members of the family Pentatomidae, and have a very distinctive, shield-like shape and are intermediate to small in size. They also get the name "stink bug" because they have tiny little glands on the underside of their body that look like little slits that, when threatened, will secrete a peppery smelled chemical that some people think stinks.

Some pinned stink bugs from West Virginia showing their body shape.

Scent glands in stink bugs on the bottom of their body. Drawing from Jason M. Squitier, University of Florida and found at http://entnemdept.ufl.edu

Most stink bugs feed on the soft parts of plants, especially the fruits and seeds. In the wild you can usually find them near trees or other plants in small numbers. However, in agricultural settings you can get them in large numbers when they find a crop of plants they like to feed on. This is a serious problem for many farmers, especially for crops such as cotton and rice. The needle-like mouth of the bug causes tiny holes in the plants, which can scar them to the point they can't be used or sold.
     One particular stink bug has received a lot of attention: the brown marmorated stink bug. This stink bug was accidentally brought over from Asia, and has caused significant damage to trees and other crops on the East Coast. It also has the annoying habit of clustering together inside houses because in their native habitat they group together on cliffs and caves to stay warm and protected during the cold months. Unfortunately houses are perfect artificial "cliffs" here in the United States.

However, there are some that are actually useful for keeping pest insect levels down in some crops or other agriculture because they feed on other insects. These bugs are part of the group Asopinae, which are also unique because they are able to bend their needle-like mouth parts forward to stab their prey. They are especially effective against caterpillars or other insects that can damage plants.

  The reason I like to collect them, though, is because many stink bugs are really pretty. Many come in reds, blues, yellows, and a lot are various shades of greens and browns to match their plants. So, I hope to collect a few beautiful Oklahoma ones this weekend too and add them to our species list!
         Have a great weekend everyone!