These ladies just won’t leave me alone this summer. We had to remove over 10 wasps nests from our porch recently. So they get another post.
The way that paper wasps nest is that one female (called the foundress) creates the original small nest, and she lays female eggs. These eggs develop with care from the foundress. Care includes keeping the eggs humidified by adding droplets of water, feeding the larva once they hatch, and guarding the nest from ants and other attackers. This allows the young wasps to develop in peace. I had some pictures of the eggs in my last post about this guys. But this time I found all stages of development.
The eggs hatch. The first look like small squishy balls.
And, as you can see above, the eggs become squishy caterpillar like things with faces. About a week before they emerge, the female caps the capsule. At this point the larvae don’t get any more food. They are undergoing metamorphosis into adult females.
They stay in the nest capsules until they are ready to emerge as adults. Then they chew their way out. The picture below shows the first hole made by their jaws.
Once the adults they help tend the nest. They are not allowed to lay eggs, only the foundress does that. But they assist her in caring for the brood, keeping the nest clean, and defending the nest.
And now a quick note about paper wasps nesting near your house. The wasps are not usually aggressive and will mostly not bother you. However, their sting is very painful. My philosophy is that if the nest is in a high traffic area of the yard, I will remove it (like right above the lounge chairs on the porch or on the back gate handle) but otherwise I let them be. They do eat caterpillars and pollinate some flowers so they can have a positive impact.
Today I have a fun insect story for you. Last fall my (very thoughtful) mother, gave me a piece of wood that had beetle larvae in it. I have not worked with or really studied wood boring beetles so I wanted to get a look at them. I could clearly see several holes where beetle larva could be living.
See the sawdust like material around the hole? That is wood the insect has chewed up. They like to fill in the hole with that stuff. Since it was likely there was a larva in the hole, I gently split the log around the hole. And, yes, indeed there was a giant larva in there!
Seriously, it was really big.
I thought at the time that this was probably a longhorned beetle larva. The guys are sometimes called roundheaded wood borers because they borrow into wood. They generally attack weak, dying, or newly dead trees. The female will chew a slit in the bark and deposit the eggs. Many conifers and some hardwoods are attacked by this type of beetle, but they are not really a forest problem because the stick to dead and dying wood. They can cause problems with newly cut wood that is being used for building or other things. As you can see from the picture, they cause significant structural damage to the wood. I mean look at those chompers!
Asian longhorned beetles are the best known pest of this beetle group. It is not known to be in my area, but I did keep the wood quarantined just in case. In fact what I did was wrap the wood in plastic and put it in a box in my shed. Then I waited.
I’ve been checking the bag regularly for the last couple weeks as spring has really set in. Then this week, there was a new addition. I opened the bag to find this guy.
This was not what I was expecting. I thought I’d be finding a pine sawyer (https://en.wikipedia.org/wiki/Monochamus). With a little investigation, I think that this is a yellow velvet longhorned beetle. There is not a lot of research on them, but like other flower beetles they are known to visit flowers to feed on pollen and nectar (not damaging to the flowers). It is quite a pretty beetle. So yellow!
It is possible that this adult beetle came from a different larva then the one I found so I am going to keep a close eye on the log and do some research about yellow velvet longhorned beetles!
As is hopefully evident, I love insects and find them fascinating. There are certain ones, however, that I would rather not interact with too much. I like to look at them but leave it at that. One of those is the ever-present paper wasp.
While they can look just like yellow jackets, they are actually a distinct set of wasps. They are distinguished by their distinctive house building technique. They chew up plant material, mixing it with saliva to make a paper like substance. Out of this they make chambered nests. Paper wasp damage on leaves looks like scalloping. Around Colorado, I’ve noticed that they love lilac. If you see your lilacs have scalloped edges, you probably have a paper wasp colony nearby.
Their nests are usually tucked into protected areas. This one on in a small space on my rock terrace garden wall. In each chamber they lay an egg. They provision the egg with a drop of sugar water. In the picture below you can see the slightly yellow eggs and the clear drops of water. Once the eggs hatch, the female continues to bring them food.
The nest is suspended by a stalk which the wasps covers in an ant repellent chemical to keep the nest free of ants. Plus the adults (all females) guard and care for the nest constantly. When the first brood develops into adults, they help the founding female take care of their younger siblings and guard the nest.
Although I am not fond of getting to close to them and many people hire exterminators to get rid of them, paper wasps are actually beneficial in your garden. They are pollinators and are often out earlier than other pollinators. They also attack and kill caterpillars to feed to their developing young. They do sting though so it’s a trade-off.
It’s that time of year when the tulips bloom, then it snows, then it’s warm and sunny, then it freezes. All very stressful for a recently returned Colorado gardener. I was particularly sad to see my peonies slumped over after a frost last week. Luckily for them, and for me, they seem to have made a full recovery. In fact, they are flourishing and have put out more buds then I’ve ever seen on them.
While I was out examining the buds this weekend (I want flowers!), I noticed some fun entomology happening. On almost every bud there was an ant! I am new to growing peonies so I didn’t know this was thing with them. Being me, however, I am always interested in why insects are where they are and what they are doing. The ants on the buds were clearly feeding. They kept probing at the edges of the sepals on buds.
A little research on this told me that although it used to be thought that the ants were necessary for the peony flowers to open because they forced open the flowers, this is not the case. Ant-less peonies perform just as well. So what are the ants doing their anyway? Peonies produce a type of nectar (sugary water) along the edges of the sepals and flowers. In the picture below you can see the liquid pooling at the base of the bud. The ants are attracted to and eat this liquid. In this video you can see the ant checking all over for the delicious juice.
In return the ants guard the plant from herbivorous insects. This strategy is actually not that uncommon in the insect-plant world. Acacia trees and their guard ants are the classic story. The tree provides housing (in its thorns) and nectar for the ants, and the ants guard the trees from herbivorous animals and other plants. They even attack (MUCH larger) giraffes. National Geographic has an interesting story about this relationship here.
But back to my peonies. Did you notice that the ant is basically as big as the peony bud? That is partially because the buds are still relatively small but also the ants are huge!
These are carpenter ants. Carpenter ants are all in the genus Camponotus. This one might be Camponotus pennsylvanicus, but I haven’t gotten a full list of Colorado carpenter ants so I’m not sure. Carpenter ants live up to their name. They build elaborate homes in decaying and decayed wood. Unlike termites, the ants do not eat the wood. But they do excavate their houses and can cause structural problems in dead trees or untreated wood porches. Like other ants, they have a queen who founds the nest and lays all the eggs that become workers. The workers take care of the queen, the new young, and forage for food. In the spring, an established colony will produce a cohort of new queens. These fly away, mate, and found new colonies. Beside peony juice, they eat other insects they find, honey dew from aphids, other material scavenged from the forage area. People sometimes think of carpenter ants as pests because they can damage wood associated with our homes. Most of the time, however, they are manage to live without much interaction with people. I actually really like seeing them around because it means that the ants haven’t been completely overrun by Argentine ants yet. Argentine ants are another story though and will have to wait for another day.
In summary, the carpenter ants are not hurting the peonies, and there is no need to worry about them. They are just doing what the plant wants them to do.
Most insects are solitary, meaning the live their lives alone expect for mating. There are some insects, however, that have more complex social structures. Insects (and other animals) can be classified by their social arrangements. The most common categories of social arrangements are presocial, subsocial, communal, quasiscocial, and eusocial.
Presocial: Some otherwise solitary insects come together at certain points in their lives to build new nests or participate in mating. These are called presocial insects. Subsocial: An insect that cares for it’s young but does not interact with it’s peers is subsocial. The ground nesting bees I wrote about in an earlier post are subsocial because they provision their young with food. Communal: Insects that live in a common dwelling but care for their own young are communal. Some types of bumble bees are communal because they build a shared, underground nest but each female cares for her own young. Quasisocial: Similarly to communal insects, quasisocial insects also share a dwelling. But the young (often called brood) are care for collectively. Eusocial: Eucosial insects share a nest and cooperatively care for the young. Additionally, they have reproductive castes and that adult generations overlap. Reproductive castes means that only some members of the nest are allowed to reproduce. For example, only queen bees lay eggs while the other bees have different tasks such as foraging and caring for the young. Overlapping generations means that the young and multiple generations of adults are present at the same time. Eusociality is somewhat rare and is confined to two insect orders: Isotera (termites) and Hymenoptera (ants, bees, wasps). All termites are eusocial as well as all ants. Bees and wasps each have each have about 600-700 eusocial species. Honey bees are the most common example.
Now that the terminology is out of the way, I want to talk specifically about termites. They mostly get attention for being destructive, but really they are very interesting insects. By sheer numbers and range, they are one of the most successful insects. Termites are found on every continent except Antarctica! They live in large colonies and have an extensive caste system that divides labor: workers, soldiers, and reproductives.
Workers are the numerically the largest caste although they are physically the smallest. Their job is to find and digest the cellulose in wood and provide food for the colony. They are small and usually light colored. Below are pictures of eastern subterranean termite workers peeking their heads over ground.
Soldiers are physically larger than the workers. Their job is to guard the workers and the nest. In many species the soldiers have large jaws. In fact their jaws are so large they cannot eat and have to be fed by the workers! I do not have a good picture of a soldier, but this video on youtube is a pretty good demonstration of how big and aggressive they can be.
The reproductive caste is established at the start of a new colony. Only one male and one female, called the kind and queen, will reproduce in each colony as long as they are alive. This is different from the eusocial Hymenoptera, which only have queens. Heirs to each position are also kept in the colony in case one of them dies. Kings and queens are larger than the other castes. Below is a picture from http://lpm.net.au/termite-management/termites/ that shows a huge queen, the smaller kind and soldiers guarding them.
The queen produces workers and soldiers to maintain the colony but also new reproductives to create new colonies. This is how a colony reproduces. The new reproductive termites have wings and leave the colony to go found new colonies.
Often this happens all at once, called a reproductive swarm. This is a video of subterranean termites coming up in a reproductive swarm. And this is what the swarm looks like as it’s trying to disperse. Reproductive swarms often happen in spring when the ground is moist so keep an eye out for them! Hopefully you will see them while out hiking and not near your house.
This social structure has worked well for termites. They have been successful for millions of years and will likely continue to be.
People who garden or keep houseplants are bound to encounter insect pests eventually. As I mentioned in an earlier post about fungus gnats, keeping track of the insects in your plants and gardens is the first step in managing the problem. Fungus gnats are easy to monitor using yellow sticky traps. Some pest, however, are harder to find. Sometimes damage on the plants themselves is what alerts you to a problem.
This happened to me last week with my wood sorrel (Oxalis Acetosella) houseplant. I noticed that its newest mature leaves were crimped. And the older mature leaves had clear patches on them.
The crimping is caused by early damage to young leaves by thrips and aphids. In order to determine which problem I had, I gently shook the leaves over the table. Juvenile thrips and live aphids were crawling around on the tabletop! And not only live aphids, but a whole bunch of their dried molts. Aphids, like other insects, shed their exoskeletons periodically in order to grow larger. This process is called molting. The presence of aphid molts tells me that they have been there for a while.
The reason that it took me so long (too long!) to spot this infestation is that there is a delay between when the damage occurred and when it becomes visible. The crimping in the leaves is caused by thrips or aphids feeding on very young leaves. As the leaves grow, the damaged areas cannot, distorting the leaves. This problem is certainly not specific to wood sorrel. In fact, crimping and other distortion from thrips is a big problem for many crops. Strawberries, for example, can have serious damage from thrips. When thrips feed on strawberry flowers, you cannot see it at the time. But it causes fruits to mature in irregular shapes or never fully ripen. The frustrating part is that you don’t know that there was damage to the flower until the fruit is already formed!
So keep your eyes open for any sign of insect damage. Shaking the plants gently onto a white sheet of paper is a good way to see what is on them.
Two of my good friends from graduate school, Lauren Ponisio and Katherine Wilkin, recently published a paper about their work on pollinators and forest fire. If you have access to Global Change Biology you can read the whole the here. (Maybe I should have a post about how ridiculous the current publishing system is, but that will have to wait for another day.)
Kate and Lauren spent many many hard hours hiking around Yosemite documenting pollinator diversity in places with a variety of fire types. Backpacking through Yosemite for work sounds like a pretty nice gig, right? And it can be. But it is also very hard work with long hours and uncertain rewards. This thing with research is that you mostly don’t know what you are going to find. You can have a good guess, but you’ll never know for certain. You could spent two summer collecting pollinators in the far out areas of Yosemite and then learn that fire diversity is not related to pollinator diversity.
But luckily for Lauren and Kate, that was not the case. The found, basically, that forest fires allow for more flowering plants in forests, which is good for pollinator diversity. More specifically, in areas in which there were a diversity of forest fire types, there were more flowering plants and more species of pollinators.
What is fire diversity anyway? There are different kinds, types, of forest fires. Some burn along the ground, feeding on dried grass and dead trees and never getting that hot. Or they can burn hot and in the tree tops, killing trees along the way. There are others in-between but you get the picture. Fire diversity is a measure of how many different types of fires occur in an area. Different types of fires have never different effects on the surrounding environments.
The policies of fire suppression that have been in place in the US for a long time have created conditions in which we often only have the most extreme type of forest fires. These extreme fires kill a lot of tress and cause significant destruction in an ecosystem. Kate and Lauren studied areas under that had had fire suppression and extreme fires as well as places that had more natural fires. The areas with more natural fires had more pollinator diversity (meaning there were more species and they were more abundant).
Fire diversity is important for maintaining pollinator diversity in our forests. As Lauren and Kate suggest in their paper, this information is important for fire manager to know. Changing fire management practices, shifting away from suppression, would be helpful for pollinators.
If you want to read more about Kate’s work with fire management, she has a great blog post from last year on our department’s site. Check it out! website http://ourenvironment.berkeley.edu/where-fire-working-california#1