Pond creatures

Our house came with a pond, which, as an entomologist, made me nervous. Because, well, mosquitoes live and breed in standing water. Technically only the larval stages live in the water, but mosquito larvae turn into mosquitoes! And mosquitoes ruin nights on the porch and outdoor dinners.

Female mosquitoes are the only ones who bite. They are looking for blood because they need to feed before they can lay eggs. Interestingly, it is not the mosquitoes bite that makes your arm swell and itch. That happens because people’s immune system react to the bite with inflammation and itching.

Anyway, backyard ponds can be a large source of mosquitoes. So I was nervous about the pond, even though it is pretty.

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The first summer we put in about 15 small goldfish, which actually thrived. They more than tripled in size over the summer. I assume that they were getting fat on mosquito larvae because we didn’t see many mosquitoes in the yard. Same for the second summer. But the third summer was different. We changed the pond liner and the fish store was having some issues with their fish stock. We weren’t having any luck with the fish, and I was sure that the mosquitoes were going to get out of control.

But they never did. When I finally went to investigate, I found out why.

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The pond was full of damsel fly nymphs! There may also be some dragonfly nymphs but it’s hard to tell without catching them. For more about how to tell them apart and some biology see my older post about this https://getbuggy.wordpress.com/2015/07/31/dragonfly-damselfly/. These nymphs are vicious underwater predators (of things their size, no need to worry about your toes), and we had hundreds of them living in the pond.

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They were constantly patrolling the all surfaces in the pond. And nothing was getting past them!

Once they’ve gotten their fill of mosquitoes and other underwater creatures, the crawl up on a rock and split their exoskeleton open to become an adult. Going from what is around the yard, I believe that most of the nymphs become these pretty blue damselflies.

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They are also predators as adults. They are like the cheetahs of the insect skies, hunting insects in flight and attacking quickly. So they continue their hunt for insect prey out of the pond, which would help with any adult mosquitoes that come to the pond to lay eggs. And other insects. Actually, now that I think about it, they might be eating bees but I guess that is nature.

Dragonflies and damselflies are part of the insect order called Odonata. This order is very old, evolutionary. There were Odonates flying around when there were dinosaurs! In fact, they are thought one the insect lines that first evolved flight.

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While dragonflies and damselflies are not usually not on the list of beneficial garden insects, I’ve come to greatly appreciate them this summer!

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Aphids in the sky and underground

It’s spring! Well today is the first day that feels like summer, but it’s spring. In places where plants die back in the winter, spring is a full of new growth. And lots this new plant growth seems to miraculously get covered in aphids. Where do they come from?

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While some of them may already be in your plants, hitting as eggs, some literally fall out of the sky. It’s a strategy for finding new habitats. It’s amazing really. Aphids drift on the wind, high up in the atmosphere until they fall down to earth. A collection of insects at 30,000 ft found a substantial amount of aphids (and a certain type of spiders).

The chance of landing on your rose might seem infinitesimal, but there are millions of aphids floating around in the atmosphere. If only one lands on your rose, you’ve got aphids. As I discussed in a previous post (https://wordpress.com/post/getbuggy.wordpress.com/51), aphids reproduce by cloning themselves. So just one female can populate the whole garden over the summer.

But aphids are not just on the surface and in the air. They are also underground! Just like there are aphids that attack leaves, there are aphids that attack roots. They suck the juices out of the plant in the same way (see https://wordpress.com/post/getbuggy.wordpress.com/51 for more details on aphid feeding), but they do it underground.

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Root aphid on a root

This is particularly sneaky because you don’t know that they are draining resources from the plants. Plants with root aphids can have reduced vigor, wilting, and fewer flowers/fruits.

Then when it gets crowded down below, they can come up and feed on the leaves. So then you have aphids everywhere.

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Root aphid on a leaf

So what should you do about root aphids? There are several fairly effective, non-toxic ways of treating root aphids. One is the same treatment that I like to use for fungus gnats (https://wordpress.com/post/getbuggy.wordpress.com/325), predatory/beneficial nematodes. There are several species or combinations of species available on Amazon and in many garden stores. They should all work fine. They do need to be stored in a certain way and kept cold during shipping to be alive and effective.

Another way to deal with root aphids are entomopathenogic micro-organisms, mainly Beauveria bassiana. B. bassiana is a fungus that attacks insects. I’ve had the most success with a product called Mycotrol (http://www.bioworksinc.com/products/mycotrol-eso.php). The fungus spreads out through the soil and gets inside the insects. B. bassiana and similar organisms are part of the soil. It’s one of the reasons that maintaining healthy soil is so important. Because while I love aphids, I (and you probably) don’t always want them on my plants.

Happy spring!

 

Why do some insects have really fluffy antennae?

Have you ever noticed that some insects have smooth antennae while some seem to have fluffy antennae? Maybe or maybe not. But I do!

Well, here’s an insect insider fact. Most (maybe all) of the insects you see with fluffy looking antennae are male. As in many other animal species, some insects species have sexual dimorphism, which is a fancy way of saying that males and females look different. This can take many forms such as female velvet ants (pictured below) don’t have wings but males do.

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Antennae are sexual dimorphic in many insects. In order to talk about why, we need to cover some other stuff about insects. In addition to, or sometimes instead of, using just vision and hearing to navigate the world, most insects can sense their environment through chemicals. This is call chemoreception. Humans use chemoreception too, mainly through taste and smell. But for insects it’s a much bigger part of how they perceive the world and operate within it. Ants can taste the ground they are walking on through chemoreceptors in their feet. Same with butterflies. Herbivorous insects often track chemicals in the air to find the plants they need to eat. Queen honey bees suppress reproduction by female works by putting out lots of a certain chemical. And so much more!

One important way that insects often use chemicals is to find a mate. These chemicals are called pheromones. Females release pheromones that males can use to track them down. This is where the big antennae come in. It’s easier to pick up the pheromones of a female if your antennae have lots of surface area to collect and perceive molecules. The ‘fluffy’ male antennae are really highly branched, providing lots of surface area to sense incoming pheromones. Just look at the surface area of this male midge’s antennae! (I think the overwintering pupae are starting to transform into adults because we’ve seen a couple of them around the house in the last couple days.)

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Midges are flies in the Chironomidae family. Some midges bite, but many are non-biting midges like the one pictured above. Female midges lay their eggs on water. Each egg mass can contain up to 3,000 eggs depending on the species. The eggs sink, and then the larvae hatch and bury into the mud. They feed on organic matter in the water and mud. After about 2 weeks, they emerge from the water as adults. Adult midges do not feed and have only 3-5 days to live once they emerge. So finding a mate quickly is important!

I don’t have any good pictures of male moth antennae, but they are also often fluffy in appearance. BugGuide has a bunch of comparisons to look at though. Here is a link to one of male and female Luna moths. As you can see, the male’s antennae are much more branched!

Studies have shown that males in some moth species will track female pheromones over long distances. Their ability find females this way is essential for the survival of the species. This can be exploited by humans who don’t want certain insects in certain places. For example, researchers have developed methods to control pest moths, like codling moth in apples, by releasing lots of female pheromones from traps. The males follow the scent to the traps and are unable to reproduce.

Lots to think about next time you happen to look at ‘fluffy’ insect antennae!

No, the spiders will not eat all the people

I talked about this a little in my original For the Love of Spiders post, but researchers have just published an article about exactly how much spiders eat. It’s a lot. In a paper in the Science of Nature researchers Martin Nyffeler and Klaus Birkhofer estimated how they eat and, thereby, how big a role they really play in our ecosystems. In their estimate, spiders eat 400–800 million metric tons of prey each year! As the Washington Post put it, that is more than the weight of all humans on the planet. One, that’s a lot of prey. And two, that’s a lot of spiders! (Also, no spiders could and would not eat all people, it’s just a comparison of weights.)

There are  more than 45,000 species of spider that have been described and many many more that have not been described (as is generally true for all insects). Spider density and, therefore, prey consumption are greatest in forests and grasslands. Spiders, however, only play a minor role in agricultural systems. The authors speculate that this is because agricultural fields are disturbed, meaning mostly that large plants are not able establish. But, seriously, there are still so many spider in my garden and most of the production fields I’ve been in. There are so many of them, and they are so cool!

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What are their prey? And what would those prey animals be doing if they weren’t eaten by spiders?? According the literature review conducted in the paper, the top groups eaten by spiders are Diptera (flies), Hemiptera (true bugs like assassin bugs), Hymenoptera (wasps, bees, and ants), Collembola (very old insects), Coleoptera (beeltes), Lepidoptera (moths and butterflies), Orthoptera (crickets), and Araneae (spiders).

If these weren’t eaten by spiders, they could be doing things like buzzing around your head at a picnic and eating decomposing leaves. Although population growth followed by starvation would probably kill many of them even without predators.

I am going to take advantage of this occasion to put up all my pictures of spiders and spiders eating stuff that I have posted yet. I don’t have as many as I should really, but I like them anyway. I am going to go in order of frequency of prey. Flies are very common so it makes sense that they are a main prey item. Here is a picture of a spider eating a hover fly in my garden.

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Hemiptera, the true bugs to an entomologist, include sedentary insects like aphids, which make easy prey for hunting spiders. I’ve never actually captured that on camera or video, but I’ve seen it happening. Bees and wasps are also very common and often visit flowers for nectar. A flower is a good place to be grabbed by a spider, as is happening in the picture below.https://getbuggy.wordpress.com/2016/02/08/for-the-love-of-spiders/.

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I don’t have pictures of spider predation of Collembola, Coleoptera, Lepidoptera, or Orthoptera. I’m actually pretty surprised that I don’t a have photo of spiders eating moths since moths are often caught in webs. Here is a spider of a web though. Orbs spiders, like the one pictured below, are common web predators in gardens and forest. Despite the fact that they look scary, they are harmless.

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That’s all I’ve got for now. Don’t let the spiders eat you!

A brief foray into another type of invertebrate

This blog is pretty much about insects because that is what I am interested in and what I love taking photos of. However, we’ve recently had a pretty crazy experience involving another type of invertebrate, and it was just too weird not to put up here.

A little over a month ago, we got a salt water fish tank (clearly a dog, two cats, and 6 chickens is not enough pets). We got the tank on Craiglist from a person who didn’t have time anymore to deal with it. It was a fully set up  6-8 year old, 30 gal tank with two fish, two snails, a shrimp, lots of mushroom coral, a torch coral, and two smaller unidentified corals.

There was also about 10 lbs of live rock. Live rock, which it not actually alive, houses all sorts of tiny beneficial organisms that act as a biological filter in the tank. These days much live rock you might buy is made in ‘captivity’, meaning that it was not harvested from the ocean. But this did not used to be the case. Our tank had been set up with this rock 6-8 years ago, and it’s safe to say that this rock came from the ocean. How do I know that? Well, the rock was not the only thing from the ocean in the tank. And I am not talking about the fish, which I knew were there of course.

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One night I happened to glance at the fish tank on my way out of the living room and saw a blur of motion that disappeared into a hole in the rock. I thought I’d seen legs and nothing in the tank should have had that many legs… so I got a flashlight and tried to look into the hole. I could just make out something that look kind of like shrimp antennae, but the shrimp was in a different part of the tank. After some internet research, I thought maybe we had a large bristle worm… but they don’t have antennae like appendages so I wasn’t convinced.

Every morning I’d creep into the living room to see if I could get a glimpse of the thing before it knew I was there. And eventually I did! It was, indeed, not a bristle worm. It looked like a large underwater centipede. SO MANY LEGS. Further internet research seemed to indicate that what we had was actually an Eunice aphroditois, also known as a bobbit worm. This realization was quickly followed by a plan to get it out of the tank before it started eating the fish and coral. And also the realization that I had TOUCHED it’s house when arranging the fish tank! I haven’t put my hand in the tank without gloves since.

Like many many ocean creatures, we don’t actually know all that much about E. aphroditois. The have been found in relatively shallow to somewhat deep water (10m to 40m). They are ambush predators that bury themselves in rock or sand. They sense fish and other prey with the five tentacles on their head (the things that I thought looked like antennae). They catch fish with their sharp jaws and drag them back into their burrow. Here is a cool, if somewhat overdone, video of it https://www.youtube.com/watch?v=5_bzyAlspNI (not one I took). The worm has a powerful bite and can cut fish in half. Some sources say that they can cause permanent paralysis to humans (I touched it’s house!). They are believed to be broadcast spawners, but no one is really sure about what the eggs look like or where they develop. Some scientists also believe that what we call E. aphroditois is actually a number of different species (differentiating species can be really really hard). This means that identifying its exactly behaviors and life cycle is even harder because there could be multiple species with different traits.

Removing a bobbit worm from a tank is hard. So we blocked out 6 hrs on Saturday evening for the challenge. Luckily some lovely friends wanted to join in the process, which certainly made it more fun. We put it’s rock in the a bucket of tank water in the dark basement because the worms only come out when it’s dark. We created a red light flashlight to use because the worms cannot see red light.

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We started by trying to lure it out into a trap with shrimp bits. It came out about 4 inches but wouldn’t go into the trap. Then we tried to lure it into a lasso. It would go through the lasso and grab the shrimp bait but it was too fast to catch. Even if we had caught him, they are really hard to get out of their holes because they dig their back legs in. People have created very elaborate pulley systems to pull them out of their rock holes. That seemed impossible in our case. So we then resorted to our final option: break the rock apart with a chisel.

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Somewhat amazingly we managed to keep it alive through out the process. We got it back into salt water in a Tupperware pretty quickly. Actually once it was partially exposed, we got it out by putting it’s head in the water. It then slithered out.

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And then in full nature-nerd mode, we watched it for a while. Here is a video of it https://youtu.be/mjfVXKYw0W4.

It is pretty creepy (and very crawly!) but that’s kind of my style. It was a rainbowy shimmery color and had so so so many leg appendages. Really a very cool creature.

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We might have kept the worm if we wanted a second tank (and it didn’t possibly cause permanent paralysis). But instead we gave it to the Denver aquarium. To me, it’s a reminder that there are so many animals/plants/organisms out there that we do not know much about. The world is an incredible place, and there is a lot of exploration left to do!

 

A balancing act

It’s been a while! I got busy and then it was winter, a less inspiring time for insect photography. Recently, however, I got asked to give an insect related talk at a conference, and it’s motivated me to get this up and going again. Also my wood sorrel just got aphids again.

How to control insect pests while getting most of what you want is an age-old problem in both agriculture and horticulture. Looking at it through an ecological lens, there are really two main approaches; we call them top-down and bottom-up. Top-down is exerting control from ‘above’ the plant. This includes natural ways, such as using predatory insects, and chemical ways, mainly insecticides. This area gets a lot of focus. What insecticides work best? When should the beneficial insects be released and how many do you need?? I think about questions like these a lot, both professionally and in my own garden. And I like to take pictures of the process, like this lady beetle eating an aphid (providing top-down control).

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A convergent lady beetle eat aphids

There is a lot of advise out there about how to manage top-down control. But top-down is not the only way to control insect (or non-insect) plant pests.

Bottom-up control refers to mechanisms for control that go through the plant. There are many variations on this. One you may have heard of is resistance. Some plants are resistant to certain pests or diseases. For example, some tomatoes are resistance to a disease called fusarium wilt. Resistant tomatoes will not suffer from the disease like susceptible tomatoes even though they are treated the same. You can see this clearly in this photo from the Missour Botanical Garden (http://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/pests-and-problems/diseases/cankers/fusarium-wilt-of-tomato.aspx)

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Some plants deter pests from eating them by tasting bad to particular pests. This is a whole field in ecology, but for our purposed today, we are just going to say that this is a form of bottom-up control.

The type of bottom-up control that I want to talk about has to do with the inputs a plant gets (how much fertilizer, water, sun, etc) and how those affect both pest and beneficial insects. Just like a child’s diet impacts how various aspects of their development, a plant’s access to nutrients, water, and sunlight changes want the plant will look like as it grows. It also changes how the plant responds to insects and how insects respond the plant.

The most basic version of this is that giving a plant more nutrients can increase the number of pest insects attacking the plant. This is common for roses. If you over-fertilize your roses, you are very likely to have lots and lots of aphids on those plants, especially if the roses also have lots of water. The rose pictured below, for example, was covered in aphids.

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Aphids get their nutrients from the plants they feed on. So when a plant has more nutrients, more of them get passed to the aphids. Then the well-nourished aphids can grow and reproduce faster. This leads to larger populations of aphids on the well-fed and well-watered roses. As long as you are not giving them WAY too much water and fertilizer, these roses will usually make more flowers for you to look at as well, which is why people feed and water their roses in the first place!

But the interaction can get even more complicated when you start to look at beneficial insects too (adding in top-down control). Sticking with the roses example, let’s say that lacewings and parasitoid wasps (how have I not done a post on those yet?!) are attacking the aphids. Juvenile lacewings, like the one shown below, eat the aphids.

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3rd instar lacewing larvae

The well nourished aphids on the well nourished plants are bigger, meaning one aphid is a larger meal for a lacewing. This can lead to the lacewings actually eating fewer aphids, since each individual aphid is more food. In this situation, the lacewings are providing less top-down control than they would on a plant with less-nourished, smaller aphids. This is doubly bad for the plant; it has more aphids because they are growing and reproducing faster AND fewer of these aphids are being eat by lacewings.

But what about the wasps? First, some parasitoid wasp biology. 1) The wasps lay one egg inside of each aphid they attack. 2) Only the females do this. 3) Wasps can determine the sex of the egg they lay (another future post). With that covered, I’ll continue on.

Many species of parasitoids will choose to lay female eggs in larger aphids (like those larger aphids on the well-nourished roses). This leads to an increased in the proportion of female wasps in that population, which in turn leads to more aphids being attacked since only females attack them. So this can mean that while a well-nourished rose bush is getting less top-down control from lacewings, it is getting more from parasitoids. And parasitoids are almost always more important in top-down control than lacewings.

Striking the balance between top-down control and bottom-up control to achieve the biggest yield (roses in our example, but it could easily be soybeans), is a tricky business!

 

National Sneak Some Zucchini onto your Neighbors Porch Day

It’s mid August, and most people with gardens are over-run with squash and zucchini. There are many jokes are trying to foist your extras off on other people. This year I learned that there is actually a holiday for this, National Sneak Some Zucchini onto Your Neighbors Porch day (http://www.nationaldaycalendar.com/national-sneak-some-zucchini-into-your-neighbors-porch-day-august-8/)! I didn’t learn about it in time to celebrate this year, but next year I will be participating.

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Squash and zucchini are fruits, and, therefore, need to be pollinated. They are pollinated by bees. In fact, they are in the genera Peponapis and Xenoglossa, and they are one of the most important pollinators in agriculture. These bees also pollinate pumpkins and other winter squashes.

If you have squash plants of any sort, you can mostly likely find these bees in the flower in the early to mid morning. I find them every time I look in the morning. While they are similar size to honey bees, there are several distinguishing features that can help you tell the difference. The best one is that the squash bees have longer, darker antennae.

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They also have dark rear ends with more defined stripes.

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As you can see in the last photo, you will often see the bee with it butt up and it’s face in the flower. They are drawn to the nectar at the bottom of the flower. In fact, they are using their extra long, forked tongues to lap up it up. Below is a picture of the bee’s tongue. Because I was focusing on the tongue, the bee is just a black blob, but you can see the forked tongue licking the bottom of the flower!

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And one more just cause it’s cool.

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They move their tongues all around the base of the flower, lapping up all the nectar. It is mostly the female bees that do this. The male bees fly around from flower to flower looking for a mate. The females nest alone, digging 1-2 ft burrows with chambers at the end. They lay their eggs in the chambers and provision them with pollen bundles. If you watch the loose dirt areas of your yard or open space, you can often locate the nests of ground nesting bees, including squash bees. Just be careful walking over them!

Interestingly, after a frenzied morning, the bees go to sleep in the flowers which wilt and close the bees safely inside. I discovered this when I picked a wilted flower and 3 bees started buzzing inside! A little research showed that this is a common behavior for this bees and not a mistake. So be careful with wilted blossoms. And remember to thank the squash bees if you are the recipient of National Sneak Some Zucchini onto Your Neighbors Porch day.