A Week's Worth of Thistle

Episode 3

 On a particularly windy day, I checked on the thistle plant to find a new drama unfolding. Two metallic spiders were signaling back and forth. The smaller, green spider I took to be the male and the larger, dark purple I figured was a female. They looked like jumping spiders, but with long abdomens that made me think of ants. They were so focused on each other, I even managed to get a video of the male attempting the court the female, and then fleeing for his life when she charged forward.

 I figured that there would be at least some research done on these guys since they're so brilliantly colored and somewhat charismatic. Nope. All I found was a video on youtube with little to no information. I had to dig through a dichotomous key just to find the scientific name Tutelina elegans, which after plugging in to Google Scholar, gave me only papers that list jumping spiders in different states. After digging around some more, I found just a snippet of information saying that they are ant mimics that specialize in hunting them. This is interesting since ants are usually tough and sometimes toxic, so most spiders avoid them.

This lack of a common name and life history, shows just how little we know of the invertebrate world. How can we claim so much about the world around us, and yet not pay attention to the smaller creatures that abound right under our noses? It's things like this that push me towards the study of insects, since there obviously are holes in the information we claim to have.

A Week's Worth of Thistle

Episode 2

Another search of the thistle left me somewhat disappointed. The Fourlined Plant Bug had gone and the tortoise beetle larvae, as if channeling their common name, seemed to have only grown and not moved. I looked on every leaf for something exciting, and finally turned to the stem.

A pocket of foam made me curious. I thought that it might possibly be an egg case, which was exciting, but then I reasoned that the foam was too fragile and wet to be a proper egg case. So, yet again, I decided to look it up. 

The most likely cause of the foam was a Spittlebug. Spittlebug's are the larval form of insects commonly called Froghoppers. The adults are the tiny, pill-shaped bugs (and it's a Hemipteran so that's correct) that land unexpectedly on arms and legs, and upon closer inspection, will explosively jump away.

The larvae, or nymphs since they are hemimetabolous, feed on the plant's inner fluids, which are then converted to the foam. The foam, like the tortoise beetle larva's shield, provides multiple forms of protection. For one, it keeps the nymph out of view and prevents it from desiccating, and it also helps regulate temperature. 

Again, these guys are considered pests, but one or two will only cause minor damage to a plant that it can easily bounce back from later. If you would like a view of these guys, you can actually use a blade of grass to break up the foam to see a tiny off-white nymph underneath.  

A Week's Worth of Thistle

Episode 1

After a short span of time had lapsed, I returned to the thistle. I found that the tortoise beetle larvae had grown substantially, along with their shields, and that we had a newcomer.

I could tell by the piercing mouth parts that it was from the order Hemiptera, which contains "true bugs". Yes, that's right, there are a group of insects that it is perfectly acceptable to call them "bugs" without anyone being snobby and going "I think you mean, 'insect'." Anyway, I know the image isn't the best, but this guy was racing around so much I could barely catch up (plus I was using my phone's camera). So with my cruddy image, I tried to ID this guy. I figured with such a striking coloration of brilliant lime green contrasting with the black I wouldn't have any trouble. Unfortunately, I needed to get a better dorsal picture to be confident in my ID'ing, but I'm fairly certain it's a Fourlined Plant (or Leaf) Bug.

These are considered pests of perennials, and leave a distinct mosaic pattern on the leaves they feed on. The thistle did not exhibit this sign of feeding, so I assumed it was more interested in the flowering plant the small plot was originally intended to grow.

A Week's Worth of Thistle

Prologue

Last week, while cleaning the garage, I noticed something on the thistle that had invaded the small flower bed just outside. I got closer and found what almost looked like a pillbug, but with something on its back.

After extensive researching, I found that it possibly was a tortoise beetle larva. These little guys keep a pile of waste (basically poop and exuviae, or shed skin) on their backs as a means of defense. These work in a couple of ways, for one, a predator flying in might take a piece of this shield rather than the larva by mistake, or, depending on the larva's diet, the shield may be full of foul smelling and tasting chemicals.

When I found this out, I returned to the plant to get a closer look at these guys, and was surprised at what I found.

A spider had captured one of the larva despite the shield being in place. It made me wonder how the spider navigated around the shield in order to catch the tasty meal underneath.

It was at this point that I decided that the drama going on with this single thistle plant would be my day-to-day soap opera.

Pheromone Pest Control

A study last year from Penn State has gotten my attention.

Researchers have been trying to find more effective means of controlling the invasive Asian Longhorned Beetles that have been costing taxpayers billions since their first detection in NYC in 1996. These beetles have a life cycle that revolves around deciduous trees, such as the already imperiled ash, elm, maple, and willow to name a few. These trees are popular in more urban areas where the beetles were possibly introduced through the import industry. Luckily, they've been found in mostly urban and suburban areas, but there is concern that they may find their way to our forests.

The researchers studied mate attraction as a possible means of pest control. The females will secrete a pheromone that attracts males to a tree, but repels virgin females. Even after mating, females will continue to produce this hormone to either encourage more suitors or simply keep their last one engaged, to ensure a successful copulation.

A chemist for the USDA was able to create a synthetic version of this pheromone, but I was unable to find anything stating whether it had been tested and if so, how effective it was compared to a natural secretion from a female.

Either way, this is promising news. This attractant could be used in conjunction with a biological control agent, such as a pathogenic fungus, in order to thin out the numbers in an area. Simply spray it on a tree along with some spores and wait for the males to come flying in. If those males did manage to find a receptive female before the infection got too far along, they would spread it to her and she would then spread it to any subsequent mates. Just like that, an epidemic would be going through the population.

For more information on the Asian Longhorned Beetles, check out the USDA's website dedicated to them.

I'm Back with a New Format!

It's been...wow, three years since I've posted. Quite a few things have changed since then. For one, I now have a job that makes it very difficult for me to go sampling when the sun is up, and two, I no longer have my tank to even put samples in. With this in mind, I'm going to change up the format of this blog. I'll still try to get some photos from the field, but since I can't guarantee anything, I have to change things up.

From now on, I'm going to post on issues and findings in the field of entomology that I find interesting, or at least worth letting the public know about. I'll try to be informative and not preachy, but like I said, no guarantees. Also, I'll be linking posts to my facebook page where I can more easily answer questions and read comments. All in all, I'm going to try to up my connectivity and hopefully my posting frequency.

Thanks again!