Last week (LINK) I announced a new venture to help people notice wildlife as they walk around their neighborhoods. This grew out of the observation that today too few children ever think about turning over rocks to see what lives under them. As a society, we are becoming “nature blind” generation by generation. In the hope that I might spark a small, guttering light in the darkness, each Wednesday I will post a brief introduction to one of the major groups of plants and animals that we can see “Whilst Out Walking” … starting with a run through the INSECTS for the next few weeks. I hope that you will find this interesting. We start today with Beetles. Plenty of those in the world to notice. Hard to miss.
The trouble with insects is that are just so many of them and very often they are the very devil to tell one from the other. Often, simply identifying an insect to its taxonomic family is quite a success while getting it to genus level shows that you know what you are doing. Going further down to species may require some abstruse knowledge and access to a dissecting microscope to help you count, for example, the number of hairs of a particular segment of the hind leg. Really, I am not exaggerating that much - hairs on the leg is a real life example from my student days. Our own McGill University has estimated the number of different species in Canada. At a rough count they suggest that there are 18,530 species of insects which have been named, plus another 11,800 that have not.”
Coleoptera (Beetles)
Beetles are insects (about 40% of all insects in fact - they are a very successful group) belonging to the order Coleoptera. Like most flying insects they have two pairs of wings but the front pair are hardened into wing-cases known as elytra which are protective and move out of the way when the rear pair of wings are needed for flight. Their larvae are mostly multi-segmented, often white, “grubs” with a hardened head - if you are gardener you will be well acquainted with the larvae of one species at least as these are the infamous “white grubs” that cause bald patches on your lawn.
So a “crunchy” insect with hard wing cases is a beetle.
I’ll start by taking as an example perhaps the most widely seen beetle of all. That’s right, the Ladybug/Ladybird. There are a number of species that fall under this all encompassing common name and the vast majority of the ones which can be found in your garden or sheltering in your home over winter are not even natives. All the species are placed in the family Coccinellidae.
Although there are several native species of ladybugs/birds the Asian or Harlequin Ladybug (Harmonia axyridis) was foolishly introduced into North America from Asia in 1979 to control aphids. It very much liked what it found here with the result that today it is the most common species, outcompeting many of the natives. You can tell them from the natives by the white markings on the back of their heads in the shape of a letter M or W, depending on which way you are looking at it. Just for the record, where I live, on a good day you may be able to find the Seven-spotted Lady Beetle, the Three-banded Lady Beetle, the Spotted Pink Lady Beetle, the Variegated Lady Beetle, the Fourteen-spotted Lady Beetle, the Black-spotted Lady Beetle and the Oblong Lady Beetle as well as the Asian species. May, but not easily.
Of course there are a good many more beetle species you can take an interest in. Some, well quite a few actually, are crop or flower pests. Do you grow vegetables? Then watch out for Cucumber Beetles, and the Colorado (Potato) Beetles for example and several other like nuisances. Do you grow Viburnum bushes in your garden? Then you may encounter Viburnum Leaf Beetles. The adults are small and not a problem but the larvae which in spring emerge from eggs laid the winter before in depressions or cracks in the bark are really troublesome. They are minute, very tiny indeed, but are suddenly everywhere just after the leaves unfurl and can reduce them to lace overnight.
The photo above is an Oil Beetle found in a field within the local arboretum. Quite large and very handsome. These are flightless beetles that move slowly and are to be found in wildflower-rich areas, such as grasslands and along woodland edges, where they feed on plants like dandelion and buttercups. Be careful if you meet one as when disturbed, they release an oily, yellowish substance from their leg joints which contains cantharidin, a highly toxic blistering agent. Cantharidin is a colorless, odorless fatty substance produced by male beetles and transferred to females during mating to coat their eggs for protection. This chemical is irritating and can cause severe reactions upon contact or if ingested. For this reason they are also known as Blister Beetles.
For true beetle annoyance I don’t think we can beat the infamous and ever increasing Japanese Beetle (Popillia japonica) - a hated insect and one of the most frequently seen. The larvae live underground and nibble on roots while the adults are totally indiscriminate and will eat anything green or floral. There isn’t much you can do either, short of hand picking them and drowning them in a pot of soapy water. Tedious but quite effective.
Many beetles are attractive and go about their lives alongside us. Some species will help remove carrion. Quite a few are important in recycling debris. The eponymous Dung Beetles bury dung as food for their larvae. Other such as Burying Beetles are striking and likewise dispose of carrion, while Wood-boring Beetles do this for dead trees and plants. Without the actions of insects like these we would be buried in dead vegetable and animal matter in a short time.
Then there are beetles that are quite innocuous. One example that is almost certainly in your garden is the Red Soldier Beetle (Rhagonycha fulva). If you have any of the carrot family in garden corners or on the edges of fields you will see them. Wild Carrot, Hogweed, Wild Parsnip and other related plants are often accompanied by dozens of these elongated small red beetles swarming over the flat flower heads. They are also often seen on various species of Asters. Many of the males will be quite clearly mounting the females - sometimes it seems that’s all they do, to the extent that in Europe (these are an introduced invasive species for our parts) they are commonly known as “Bonking Beetles”. The adults feed on aphids, and also eat pollen and nectar. Larvae prey on ground-dwelling invertebrates, such as slugs and snails, and live at the base of long grasses.
Then we have the Emerald Ash Borer which has single handedly been responsible for the death of almost all ash trees in North America over a remarkably few number of years. Again, not a native but ubiquitous.
The Fireflies we look out for and enjoy in our summer gardens at dusk - that is in our summer gardens if we don’t mow our lawns and allow some grasses and flowers to grow tall enough to welcome them - are beetles too. Not flies at all.
And not all beetles are black - many are very attractive. This Longhorn Beetle for example:
Looking for Beetles
There are beetles adapted to most habitats, some of them quite extreme. However, on a walk near your home of poking about in your garden first look in dark and damp areas such as under rocks and logs, and near ponds and streams - environments that provide food and where they can shelter from predators. Decaying wood attracts them.
“It is amazing what a lot of insect life goes on under your nose when you have got it an inch from the earth. I suppose it goes on in any case, but if you are proceeding on your stomach, dragging your body along by your fingernails, entomology presents itself very forcibly as a thoroughly justified science.”
- Beryl Markham, West with the Night
Next Wednesday we will look at the Lepidoptera (Moths & Butterflies)
From noted biologist J.B.S. Haldane: "The Creator would appear as endowed with a passion for stars, on the one hand, and for beetles on the other, for the simple reason that there are nearly 300,000 species of beetle known, and perhaps more, as compared with somewhat less than 9,000 species of birds and a little over 10,000 species of mammals. Beetles are actually more numerous than the species of any other insect order. That kind of thing is characteristic of nature." [Note: The more famous, but apparently apocryphal version of this quote is "God has an inordinate fondness for beetles."]
Excellent introduction to beetles. I've seen very few Red Soldier Beetles this year, they're usually common round Edinburgh. Harlequin Ladybirds have been introduced here too and are taking over, though early this summer we had a huge number of Seven Spot Ladybirds, I've never seen so many since the summer of 1976 (which is still remembered in the UK as the year of the ladybird 'plague')