weevil

It’s that time of year again: the time of year where my quantity of photos taken begins to exceed the quantity of photos I can work onto the blog. I take my camera with me virtually everywhere: every time I go out on a walk with Raven down the road, or a hike with Dan out in the park, or out to visit friends or family. I even take my camera when I go grocery shopping in town, just in case I should happen to encounter something along the way (this was prompted by encountering a young snapping turtle in the middle of the road last summer, so I stopped the car to get out to help it across, and I was kicking myself for not bringing my camera). If there’s anything that catches my eye or even slightly piques my interest, I take a picture. Many of these, the odds and ends that I can’t work into a full-length post very easily, languish in my computer’s annals. During the winter the problem isn’t pronounced, but as soon as spring starts to break, my backlog of photos really begins to build, and I just can’t keep up with all the subjects I take photos of.

Last year I tried addressing this through Today at Kingsford. I felt it was mildly successful, but ultimately still left lots unshared. This year I decided a better way to approach it would be to emulate the day-labeled themes such as “Skywatch Friday” or “Wordless Wednesday”, and start a regular series called Monday Miscellany. Although in my head Saturday is the most logical day for a week-end round-up, “Saturday Miscellany” just didn’t have the same sort of appealing alliteration. So Monday it is.

This week’s header image is of a Green-margined Tiger Beetle, Cicindela limbalis. At least, I think that’s who it is; tiger beetles tend to be somewhat similar in their markings and general colours, and I’m certainly no expert, unlike fellow blogger Ted of Beetles in the Bush. It doesn’t help that my primary reference for all things six-legged, the Kaufman guide to Insects, only covers a subset of the more common tigers. So I turned to a book that I haven’t used a whole lot recently, largely due to its tome-like size: Stephen Marshall’s Insects: Their Natural History and Diversity. This is a great book, with a much greater breadth of diversity than can be offered in the smaller Kaufman guide (Marshall’s book is hardly a “field” guide, but makes a great coffee-table reference). I rarely fail to find what I’m looking for in there.

In this case, Marshall notes, “The Green-margined Tiger Beetle lives on clay soils across Canada and the northeastern states.” BugGuide.net, my number one online reference for all things six-legged, adds that the habitat is “usually steep, moist bare clay soil, including… dirt roads”. They’re out in the spring and then again in the fall. I spotted it moving along our dirt road one warm afternoon last week as I was returning with Raven. She was very good as I asked her to sit-stay while I photographed the critter. The beetle was also very good, though I doubt it paid any attention to my command to sit-stay. Prior to this I had only ever seen Six-spotted Tiger Beetles (C. sexguttata), so I was rather excited to discover this one.

Insects figure heavy in this post. I’ve been seeing quite a few about recently, particularly late last week on perhaps the most gorgeous afternoons we’ve had so far this spring. This one is a bee fly, probably Greater Bee Fly, Bombylius major. This is a widespread species that flies in early spring (BugGuide.net says they’re most common in April), usually found near wooded areas, in sunny clearings either sunning themselves or visiting spring wildflowers. Last spring I noted one visiting the forget-me-nots in my parents’ garden. I saw four in various spots that day last week; this one was at the side of the road.

Photo number three is an unidentified weevil. I think weevils are cool, with their long snouty appearances. Although weevils are actually a type of beetle, they are generally thought of as separate organisms. Rarely any larger than a quarter of an inch, weevils are small beetles and this guy was as well. I was sitting in the leaves at the edge of a forest clearing, hoping for a bee fly like the guy in #2 (but not actually that individual) to come land near me, and I noticed this guy crawling through the litter and then up a grass stem where he helpfully sat and wiggled his antennae for a few moments while I took a photo.

On the evening that followed that beautiful day, I set up my moth sheet with great anticipation of what might arrive. I was not disappointed; I had a few hundred moths come in, of upwards of three dozen species. But they weren’t the only things to come to the sheet. There were also small beetles, a couple of ichneumonid wasps, and these guys, Giant Water Bugs, Lethocerus americanus. I encountered them for the first time last spring, at my parents’ place. They are the creepiest bugs, huge, some three inches long, with giant forearms that look fearsome. They are in fact capable of giving a good nip, and I haven’t tried handling them. They’re capable of flying, although they’re a bit lumbering as befits something of their size, and as I was standing out by the sheet it was hard not to get a little anxious with these huge bugs buzzing by me. There must have been at least 20 that arrived, drawn in by the blacklight. The leaf litter was alive with them.

At the abandoned property that I visit from time to time, some years ago the owner must have planted some spring bulbs, looking forward to a time when they would be moved in to the completed house and would have a full garden. The house was never completed, the owners never moved in, but the bulbs remain. There were crocuses, tulips, and a couple of patches of mini daffodils, all of which have grown over the years into small clumps. Two daffodils were blooming when I was there last, and were being visited by a few little insects, including this small bee (I think).

Speaking of yellow flowers, our roadside, or at least portions of it, are awash in yellow Coltsfoot, Tussilago farfara. These are one of the earliest spring flowers, and at least for the past few years, have been the first one I see in the spring. They’re such cheerful flowers, bright and sunny, it’s too bad they’re non-native.

As Raven has gotten older, she’s taken a greater interest in sticks. She never eats them, but she likes to carefully and methodically shred them to bits. No bit of wood is too small for consideration. And few sticks, it seems, are too big.

One of my responsibilities while house-sitting for my parents is keeping the bird feeders well-stocked. With the period of extremely cold temperatures (at least for this time of year – we’d be laughing come February) the feeders were a hive of activity, and the seed levels dropped steadily. The sunflower and thistle seed feeders were filled again without trouble, but when I dug the scoop into the bag of mixed seed, I noticed a sharp, distinctly mouldy smell. Peering closer, it looked like perhaps the peanuts had started to turn, and it was maybe spreading to the other seed, but I couldn’t really tell. It didn’t look really bad yet, so I stood there for a moment or two, holding the container in my hand, staring at the seed inside as I pondered whether it was still okay to put out for the birds (mould can be poisonous to birds once it’s progressed).

I finally decided better to be safe and not put the seed out, but while I was standing there contemplatively staring at the seeds, I noticed something else. Some movement. The seeds were starting to wiggle. And then…

…from between them, out crawled a tiny beetle. And then another. And a third. And before I knew it, the top was crawling with a dozen or more little beetles. More accurately, little weevils, as I could clearly see the thin snouts protruding from the front of their heads. Weevils are sometimes also known as snout beetles because of this feature. There are some 60,000 species in the weevil superfamily, Curculionoidea. Most belong to the family Curculionidae, and about 2600 species from this family are found in North America. Most are herbivorous, and many are crop pests.

Probably the interaction most people will have with weevils is the opening of a bag of something to discover an infestation of them. They are common outdoor bugs, but are generally small and inconspicuous unless they happen to land on your drink glass or some other coincidental meeting. However, they do occasionally make it home in bags of grain or seed products. There are three species, all in the genus Sitophilus, who are encountered this way, but they tend to be so similar in appearance that identification to species is best left to an expert with a microscope. They have food preferences, but there is a lot of overlap and they will opportunistically infest other sources when their preferred food isn’t readily available.

The three species are Rice Weevil (Sitophilus oryzae), Granary Weevil (S. granarius), and Maize Weevil (S. zeamais), and their common names reflect their preferred food (here in North America, maize is more often called corn). They often come home in infested bags of bird seed (Granary and Maize weevils may prefer mixed seed, Rice Weevils are often found in sunflower), but will sometimes be found in packages of rice, beans, peanuts, or whole-grain cereals. I couldn’t tell which seeds specifically had been targeted in the package, although the amount of mould growing on the peanuts made me suspicious of them. I think that the decay of the seeds that the weevils had been feeding on, whichever ones they were, had lead to the mould.

The life cycle of these weevils takes about a month to complete, and requires temperatures of a minimum of 17 oC (62 oF), but ideally 27 oC (80 oF) and above, and moderate to high humidity. The adult weevil lays their eggs on appropriate seed or grains which will become the food source for the developing larva. When the egg hatches, the larva tunnels into the grain and sets up shop inside. It takes about 3 days for an egg to hatch from laying, and then the larva may be in the grain for another 18 days, at which point it develops into a pupa. Once the adult emerges from the pupa, some 6 days later, it stays in the relative protection of the grain until its exoskeleton has completely hardened and matured, about 3-4 days.

Because they spend most of their cycle inside the grain itself, it may be possible to be harbouring these little bugs in a stored product for a few weeks without even knowing they’re there. Generally speaking, the incidence of infestation is rare, and probably even if they are present the product is consumed before the eggs get a chance to develop and we’re never the wiser (consider it added protein). By the time the bugs reach adult, stage, however, consuming them or the secretions they produce can sometimes result in E. coli infections, depending on the weevil’s particular diet.

I dumped a few out on a blank piece of white paper to try to get some uncluttered photos of individuals, but I had minimal luck. They were just too quick! I found that initially they would curl up their legs and play dead, for instance if I shook the paper to knock them all back to a central starting point. But moments later they’d unfold and start hustling across the paper. Interestingly, their direction of movement wasn’t random. They all moved with a purpose, and while their particular direction varied, it was always directly towards the edge of the paper. I thought perhaps they were trying to get away from the bright halogen that was hanging over the center of the paper to provide illumination for the photos.

None of them ever tried to fly, which I think perhaps rules out Rice Weevil, which is supposed to be winged and attracted to lights. The Granary Weevil has poorly developed wings and can’t fly, and is also not attracted to lights. On the other hand, Rice Weevils are reddish-brown and have 4 pale marks on their wing covers (Maize Weevils are similar), while Granary Weevils are reddish-brown to black and unmarked. Going by that, it looks like I have both in this group. So who knows! When I submitted the images to BugGuide.net, the person who identified them thought it safest just to leave them at genus.

Tag: weevil

Monday Miscellany

Bird seed surprise