As my trap experiment, I'm comparing location, trap contents, and trap container (mostly the container, hence the title).
I have 8 traps set up across 3 locations - 3 in one, 3 in another, and 2 in the last. Each location's traps all share an origin for the water they use and the bait they use, but each of the traps in a location uses a different type of container - either a dark blue bucket, white bucket, black bucket, or clear soda bottle. As a further variation, the soda bottle traps are much smaller that the bucket traps, giving another layer to the data.
The first set of traps - traps 1, 2, and 3 - are located near a large water quality pond (as seen below) and use its water, alongside fish food, to create an environment for the larvae. Trap 1 is made with a clear soda bottle, trap 2 with a black bucket, and trap 3 with a dark blue bucket.
The traps are set off the beaten (cemented) path and sit a bit into the forest (that is, should you be looking at the pond in the same way the photo is, behind you). They're in shade throughout the day, and when going to see them they haven't been knocked over at all, likely because there's been a couple large rocks added from the area to the bottom. There's also been a couple popsicle sticks duct taped to the edges of the containers for mosquitoes to lay eggs on (should they prefer that), but they've tended to come loose. Since these traps are set up under trees, they've gotten various debris like bits of ashe juniper (which most people call cedar, even if they're not exactly cedar trees - by the by, for those not living in the Austin area at least, these are rather plentiful), twigs, and leaves. Furthermore, since the traps use water from the nearby pond, various debris from the pond is usually in there as well.
In the image on the left is a demonstration of what the inside of the black bucket trap - trap 2 - looked like when the larvae were most recently collected. The larvae were visible on the surface - for example, the short stick-like particles visible floating over/on the rock in the bottom of the trap are larvae, as are multiple other particles (or whatever you want to call them).
The only reason I could get a picture of these like so is because the bucket had not yet been disturbed. Throughout collection efforts, I've noticed that larvae tend to attempt to escape to the bottom of the trap when their habitat is disturbed, and thus to collect and analyze the entirety of the larvae population I've been collecting the entirety of the water available, pouring the water into gallon jugs (like the Crystal Geyser spring water ones, if you know what I mean) and taking it home to analyze it in the adult mosquito-less relative safety of the AC (which is useful, because the mosquitoes and wasps in the area can be a Hazard).
The second set of traps - traps 4, 5, and 6 - are located near a stormwater drainage area that got established as a pond (also as seen below). The also use water from that pond and fish food, and trap 4 is made from a white bucket, trap 5 from a soda bottle, and trap 6 from a black bucket.
These traps are set right up against a copse of vine-overgrown trees, and also have not been found knocked over. They would have been under the trees, but they would have been even more of a pain to access than they already are, surrounded by thorny vines (that I believe are called greenbrier/greenbriar but don't take my word for it) as they are. Due to their position, they're in the sun for part of the day and in shade for part of it too. Like the previous set of traps, these are also held in place by local rocks. Unlike the other two sets of traps, these have some interesting qualities granted to them by the water of the pond they use - all three traps have already developed some sort of algae growth, much like the pond has, making the water collected from them a kind of pretty green color.
The third set of traps - traps 7 and 8 - are located on an empty lot in a neighborhood under an old live oak tree (again, as seen below). Unlike the other trap sets, these ones use good old tap water and fermented grass clippings. Trap 7 is made from a soda bottle, and trap 8 from a dark blue bucket.
The tree has left the majority of the lot covered in a layer of dead oak leaves thick enough for it to be difficult to get to actual dirt, but since it is summer and thus not tree shedding season, not a lot of leaves have found their way into the traps. These traps too have been spared being turned over, also because a couple rocks have been forcefully relocated inside of them, but I honestly wouldn't be surprised if some birds or squirrels have used the traps for their own gain - while the other two sets of traps have larger and better water sources near them that various wildlife could use, these traps don't have that. While various neighbors may have mercifully put out water, this is central Texas summer, which means being outside sometimes feels like being the witch from Hansel and Gretel about to test the temperature of the oven, and thus it would be entirely plausible that some entrepreneuring squirrels and/or birds have taken advantage of free water.
While this experimental setup has a lot of variables, most of the comparison is between the container types, e.g. the clear soda bottles and various colors of opaque bucket. Further comparison is also centered around the soda bottle traps at each location - the number of larvae from each of those can be compared to the number of larvae at the other locations, so an educated hypothesis can be (theoretically) formed about the presence of a nearby water source affecting the rate at which mosquitoes use the traps to lay eggs.
While these are the main comparisons I'm trying to look at, there's probably other comparison data that can be extracted from this experimental setup.
As my experiment progressed, I've made several observations:
1. As outside information, a discovery separate from my experiment is that spreading information about mosquitoes coming from water, as obvious as it may seem, is important. A direct example is our neighbor - unaware that this was creating more mosquito habitats, they have various vessels scattered across their backyard where water collects while they're watering their plants. One one occasion, I was able to obtain some data - below is a picture of what the contents of one of said vessels looked like. Taken just from that one, 331 larvae were counted, and while I didn't collect data from the other vessels (I'm aware I should have, but I neither had the time nor the confidence to be more overt about intruding and all), I made sure they were emptied.
2. As part of regularly collecting data, I one day endeavored to collect the water from my traps to analyze larvae count and all at home. Due to life going on, I ended up leaving the bottles of mosquito water for a couple hours, which apparently was enough for not one, not two, but seven of the larvae to decide it was high time to sprout wings. Below are two pictures of them, but at least four took a break for it the moment the lid of the container was opened. The container was from Trap 2.
3. I've noticed that in several of my traps where I used to have a lot of mosquito larvae I now barely have any, if any at all. These traps have something in common - odd worm-like things that I believe are planaria. A picture of one is attached. One of the things planaria eat are arthropods such as insect larvae, so I theorize that these guys are reducing the mosquito population - bad for the mosquitoes, and good for us.
4. After some deliberation and research, I believe the type of 'algae' in the water in traps 4, 5, and 6 is Cyanobacteria. Though I may be wrong, I suspect that it really is cyanobacteria, because in my most recent data collection traps 4, 5, and 6 did not contain any mosquito larvae - only some empty larvae skins (1 in trap 4, 4 in trap 6) and a couple culex mosquito eggs (trap 6). This is significant because according to the abstract of the article linked below, the toxicity of cyanobacteria can kill mosquito larvae. Furthermore, trap 4 is a white bucket, and trap 6 is a black bucket, and collected water from trap 4 held visibly a lot more cyanobacteria growth than trap 6, since trap 4 had clumps of cyanobacteria in it and the water collected from it was very, very green, and trap 6 had more greenish-cyan-colored water and practically no algae clumps.
We attempted to follow the directions of the other linked article to test whether it was truly cyanobacteria, but we weren't able to collect any of the actual physical algae in a bottle or ascertain via the stick test because the pond has a lot of other algae that interfered with conducting both tests.
Here's the article: https://pubmed.ncbi.nlm.nih.gov/17855939/
Cyanobacteria test: https://www.pca.state.mn.us/sites/default/files/wq-swm1-04.pdf
Here's a couple pictures of the water, though:
As for a final count of all of the data I've collected, here's a spreadsheet that I've made to track my larvae counts:
https://docs.google.com/spreadsheets/d/19N19Tq6oiBqiXK68kIQUtE10w8cUqvxEV1C8ABYIzek/edit?usp=sharing
And here are some charts I made for each trap I had:
Interestingly enough, Traps 5, 6, and 8 had spikes in larvae counts around July 4th, and Traps 1, 2, 3, and 7 had spikes around June 20th.
While it does seem that the soda bottle traps had higher larvae counts than the other types of traps, I now realize that there are several uncertainties that may have affected my data, such as when it was collected. For example, the very last set of data was collected slightly before a full week had passed, as well as a couple others, which may have affected how many of the larvae were still larvae, especially considering that on some occasions adult mosquitoes had appeared between the time of collection and the time when the larvae were counted. Also there may have been interference from the local wildlife - and plant life - that we may not have factored in. For example, raccoons are a bit of an issue around our our area, we observed things other than mosquitoes in our traps such as (possibly) planaria, and there was various plant life that got into the traps that may have affected the bait - for example, the traps with fish food bait technically didn't only have fish food in them, but also had fermented bits of leaves and twigs and et cetera that may have also served as bait much like the fermented grass served as bait.
From my observations, it seems like containers in shade, especially the smaller clear soda bottles, were more preferred, but there should be more research performed to discern which specific part the mosquitoes are more drawn to. Is it the size? Is it the fact that the container is clear? Is it some other factor I haven't considered?
Research can tell us a lot, but can also go on forever, trying to narrow it down to a very specific certainty.
About the author: Valentina is a student from Austin, TX. This blog describes a mosquito trapping experiment conducted as part of the NASA STEM Enhancement in the Earth Sciences (SEES) summer high school research internship. Her virtual internship is part of a collaboration between the Institute for Global Environmental Strategies (IGES) and the NASA Texas Space Grant Consortium (TSGC) to extend the TSGC Summer Enhancement in Earth Science (SEES) internship for US high school (http://www.tsgc.utexas.edu/sees-internship/). Valentina shared her experience this summer in this blog post.
