Wasps: Not Just Flying Agents of Pain

One of the things I encounter a lot when I talk to people about pollination is an intense fear of bees, and most especially of wasps. But wasps don't just sting you (and most won't sting without provocation); they also are pollinators. While on holiday at the lake, I captured a great series of a wasp worker hanging out on Achillea millefolium.

Unknown species of wasp on Achillea millefolium

Wasps are generally less hairy/fuzzy than bees, so they don't carry pollen as efficiently. But less efficient pollination != no pollination. Indeed, wasps are important pollinators in many ecosystems.

Another possible reason that wasps aren't such efficient pollinators of bees is that they don't (for the most part) rely solely on flowers for food. This individual actually may have inadvertently provided pollination services to the flower, but wasn't there collecting either nectar or pollen. She was dining on something else entirely:

A wasp eating something - note the ball of wax-yellow stuff

So I wondered what in the world she was eating. I looked from the front angle, hoping another angle might illuminate the matter:

Wasp eating something -- ball of stuff still unidentifiable

Nope, that was no help. Still a generally formless lump of gunk.

A quick glance around the environs, however, provided the answer:

Seems like a colour match for that wasp's meal

This dead grasshopper was on the stem of the flower where I found the wasp, and judging by the colour match and the big old hole in the dead grasshopper's abdomen, I suspect that the wasp found herself a rich source of protein and was taking advantage.

I suppose one animal's rather grisly find is another's feast.

Anyway, wasps will seek out other sources of protein (often to feed their young), including other insects, whereas bees generally don't. This reduced reliance on flowers may make them less likely to do the systematic flower-by-flower collection that also makes bees such suitable pollinators for flowers.

Wasps are actually an excellent biological control agent, as many of them have preferred prey which are pest insects on crops. I encourage them in my own garden because they're so efficient at getting rid of unwanted insects.

These oft-maligned insects are actually pretty awesome -- as long as you don't swat them or approach their nests late in the season.

Syrphid Flies - Syrphidae

I have mentioned syrphid flies before on my blog, usually when mentioning the pollinators of a given plant. But what's a syrphid fly?

"Syrphid fly" refers to an entire family of insects, the Syrphidae, which are bee and wasp mimics. They resemble bees or wasps, which confers some of the natural defenses and safety that would be accorded those more dangerous species that they emulate.

Many syrphid flies are nectar and pollen eaters, and so will be attracted to flowers and provide pollination services. Many of these species are not nectar-robbers but pollinators, though we don't necessarily think first of flies when we think of pollinators.

This family is quite large and diverse. I am not, for the most part, able to identify particular species of syrphid fly. Sometimes it is obvious that two individuals belong to different species; other times, it takes close observation.

There were quite a lot of syrphid flies visiting the flowers of the insect gardens in the Montreal Botanical Gardens. They were mostly of the same size and shape, so probably the same genus. It wasn't until later when I was looking at my photographs that I realized that there were multiple species. Take this one here:

Syrphid fly

 This one has dark eyes, and a stripey abdomen which transitions from yellow to red at the tip.

Syrphid fly

This second one (I posted this photo yesterday for the discussion of Rudbeckia hirta), on the other hand, has red eyes, and a yellow patterned abdomen.

Likely these are two different species (I say likely because I am not certain of this; it is theoretically possible that there might be extreme polymorphism in a single species, but unlikely).

As I was looking through the photos another thing jumped out at me. In that first photo, the syrphid has a strange, bulgy yellow protuberance between its eyes. I wondered what it was: mouth parts? A sensory organ of some sort?

So I trotted down to reddit and asked the helpful entomologists on /r/whatsthisbug about it. I was told that that yellow protuberance is actually the antennae, which are frequently heavily modified in syrphid flies. So. Syrphids can have very strange-looking antennae indeed.