Don’t Bug Me

Oak sap insect bar 3

I am not sure what type of hornets we had nesting above our door.  They were big, but I didn’t hang out with them long enough to pay attention to their detail.  I did, however, spend some time hanging out with a different bunch of flying insects, which I only discovered were hornets when I researched my photographs afterwards.  I wasn’t thrilled when I found words like aggressive attached to them, but I guess pointing my camera at them was not too threatening.

One of our oak trees had some damage to it’s bark and was leaking sap.  I don’t know if the porcupine had chewed at it, but something had caused a wound.  It was butterflies feeding from the sap that first caught my attention and when I got closer I saw there were quite a number of different insects all feeding from the sap and some of them were hornets.

My research informed me that there is more than one type of hornet, although the definition of a hornet seems a little muddy. Basically, it seems that hornets are wasps who are large in size, exhibit aggressive behaviour and have a potent sting.

The largest hornet in my photograph, with the red wings and some red markings, is a European hornet or giant hornet.  It is the largest of the vespid species in North America and I read that it is quite rare in Ontario.  The information I found on them said that they are very aggressive, so hovering over it with my camera may have been rather risky in retrospect.

Oak sap insect bar 4

There was also another type of hornet visiting the sap, the bald-faced hornet (the black and white hornet in the photograph above).  These guys seem to be very aggressive because I later saw one attacking a giant hornet that was more than twice its size.

Wasp encounterb

Wasp encounter

It kept going back time and time again heading straight for the giant hornet.  I can’t seem to find any information about smaller hornets attacking larger ones, but that seemed to be what I was witnessing.

I was hopeful that the smaller yellow and black striped insects on the oak sap were hover flies, but having done some research, I now know that hover flies have short antennae.  I am guessing the long antennae on my visitors makes them Eastern yellow jackets; the most common of the pest wasps.  Apparently they live in colonies of hundreds to thousands of individuals, so thankfully they didn’t tell the whole family about the sap whilst I was there!

The other insects enjoying the sap were metallic green “Green Bottle Flies”.  I am sure most people know how they can play an important role in forensic science; because they lay their eggs in decomposing tissue, which their larvae feed on.  The time of death can be calculated because these little guys are one of the first insects to arrive at the scene and they hatch in 8-24 hours.  They lay 150-200 eggs per clutch and 2,000-3000 eggs in their lifetime, but the adults only live for 2-3 weeks.

These flies really are little gems.  They look like little gems and if you can get past being grossed out by the idea, I think using them for “maggot therapy” is a gem of an idea. Disinfected maggots are used on wounds that won’t heal.  They clean the wound by eating the necrotic (dead) tissue, which then helps the wound to heal.   As I was reading how this fly has been managed in “pure culture” for the last 22 years, I assumed this was a somewhat “new” treatment, but apparently maggots have been used since antiquity for wound treatment.  And why the green bottle fly larvae?  The larvae of some flies only eat live tissue, some will eat live or dead tissue, but for wound healing you need a larvae that only eats dead tissue… Lucilia sericata, the common green bottle fly.

Before I finish my potted education on wasps, I will just introduce one last wasp visitor we have seen; a thread-waisted wasp. Now this little guy is most welcome – it is not aggressive!

Thread waisted Wasp

There are over a hundred thousand different species of wasps around the world.  The yellow jackets and hornets are in the Vespidae part of the wasp family. They are social and they live together in hives.  However, most wasps are solitary wasps. Some solitary wasps do build communal nests, but each cares for its own offspring and they don’t adopt division of labour like the social wasps.  Adult solitary wasps mainly feed on nectar, but the majority of their time is spent foraging for food for their young, which is mostly insects or spiders.  The thread-waisted wasps nest in burrows and provide caterpillars for their larva.

Whilst I prefer an encounter with a solitary wasp and vespidae wasps tend make me want to reach for the nearest newspaper, I need to remember that they each play a role in wildlife.  Wasps are beneficial predators of many damaging insects for our crops.  They also feed on flies, some even eat dead flies and provide us with a cleaning service. A recent discovery is that they carry yeast cells in their guts; so maybe we should be toasting our wasp friends next time we raise our glasses!






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