“Every kid has a bug period… I never grew out of mine.”
Edward O. Wilson
When we consider biodiversity, no single taxonomic group that we can readily observe comes close to the insects. The estimates of the number of extant species ranges from a low of 1.5 million to a high of 30 million, but the latest estimates point to about 5.5 million species (Stork 2018). It should be noted that there is considerable uncertainty in these estimates because of under-sampling, e.g., northern Canada has been quite poorly sampled, and cryptic diversity, i.e., parasitic species are poorly known and difficult to study (Forbes et al. 2018). There is no great surprise, then, that our gardens and homes are alive with insects and other arthropods. A recent study discovered hundreds of insect and other arthropod species in urban and suburban homes in Raleigh, North Carolina (Bertone et al. 2016). A similar survey in a single home in Toronto resulted in the discovery of 112 species of arthropods (The Great Wild Indoors). Taking all organisms into account including all three domains, Larsen et al. (2017) in an interesting paper estimated total species richness at between one and six billion (one billion = one thousand million). If you like me learned about biology many years ago, you might not recognize many of the different taxa now. Anyway, they concluded that insects
comprise less than 8 % of total diversity as do fungi and protists, respectively, while fully 78% of diversity comprise bacteria! Of all these organisms, we have named a measly 1.5 million or so, and with taxonomists seemingly declining so fast that they would likely be categorized as “Threatened” by the International Union for Conservation of Nature (IUCN) if they were a species of animal, I don’t see us ever describing and naming all insects, let alone all organisms.
Diversity of that magnitude makes your head spin, but here I am only fortunately only concerned with organisms that can be readily seen without the aid of microscopes, which has plenty of diversity for the casual naturalist to cope with. Thefocus with our garden is to make it ‘pollinator friendly’, and I am pleased to say that we have a vibrant and varied community of pollinators. The obvious way of doing this is of course to plat a variety of favoured flowering plants so that nectar and pollen sources are available throughout the summer. But there are other ways to enhance pollinators as well. For example, those pesky weed flowers in your lawn are actually important for many pollinators – a perfectly manicured lawn is not! For example, a number of solitary bee species nest in the ground, so if you have a lush, weed free lawn, you are depriving them
of nesting habitat. If you want wild pollinators, it is important to provide areas where they can nest, e.g., areas with bare soil or sparse vegetation. Our lawn is neglected at best, which leaves it thin enough in spots to serve as nesting sites for mining bees and sweat bees (Family Andrenidae and Halictidae, respectively). I also keep mason bees, so called because they separate their brood cells with a mud wall, and consequently they need a source of mud to create those walls.
Many species of bumble bee use abandoned mouse burrows for nesting; they may
occasionally use artificial bumble bee boxes, but the occupancy rate tends to be very low. A recent student talk out of Gerhard Gries’ lab at my Alma Mater, Simon Fraser University, may offer some hope for improvement, however, so I intend to give some bumble bee boxes a try next year. I won’t give anything away here though – stay tuned for official news from the student doing the work!
The word “pollinator” is generally associated with the word “bee”, which in turn is associated with the non-native, semi-domesticated honey bee, Apis mellifera. In terms of wild bees, there are close to 500 species, and likely more, in British Columbia alone (Sheffield and Heron 2018). Some are familiar to most people, particularly the eusocial species, e.g., bumble bees. The vast majority are solitary or communal, nesting in the ground or in wood. Examples of such bees include the leafcutter and mason bees (Megachilidae), miner bees (Andrenidae), and sweat bees (Halictidae), all of which are common. But pollinators include many other groups of insects. Members of another group of the Order Hymenoptera, the wasps also contribute to pollination to some extent, but not nearly as much as bees as they lack the adaptations for pollen collection. This vast group of Hymenoptera species comprises a plethora of interesting and often beautiful garden visitors. Some are predators, e.g., the yellowjackets and hornets, but most are parasitoids, which means that they use live insects or other arthropods as food for their larvae, but unlike the true parasites, the victim is eventually killed. The bee
wolf, Philanthus crabroniformis (?), which is common here, uses various bees as hosts. Another common visitor is the American sand wasp, Bembix americana (Crabronidae), which uses flies to provision their nests. Occasionally, a green/blue jewel will make an appearance. This may be a cuckoo wasp (Chrysididae), which are kleptoparasites in the nests of other bees. They are heavily sclerotized and can roll up in a protective ball should they get attacked by the host species. There are way too many interesting species among the Hymenoptera, and I have to confess that the diversity is somewhat overwhelming, even to an entomologist.
Flies (Order Diptera) are particularly abundant flower visitors; they may not be as
efficient as bees, but they do contribute. Sometimes you may not realize that you are looking at a fly, rather than a bee or a wasp, because they can be convincing mimics. For example, hover flies (Family Syrphidae) are frequently black and yellow and can fool the casual observer. Non-mimic flies, like blow flies (Calliphoridae), flesh flies (Sarcophagidae), house flies (Muscidae) and parasitic flies (Tachinidae) are also frequent flower visitors, as are any number of smaller species. Another prominent and familiar group is the butterflies (which are even loved, unlike most other insects) and their nocturnal cousins, the moths (Order Lepidoptera). For most people, butterflies are always welcome visitors with their striking colours and dipsy-doodle flight. In our yard, the diversity has been somewhat disappointing. We have all three swallowtails that occur here (western tiger, Papilio rutulus; pale, P. eurymedon; and anise swallowtail, P. zelicaon), and we sometimes see Lorquin’s admiral, Limenitis lorquini, painted lady, V. cardui,
and frequently cabbage white, Pieris rapae. On one occasion each we have seen a mylitta crescent, Lycaena helloides, and a pine white butterfly, Neophasia menapia. We also have had three species in the family Lycaenidae (blues and coppers), and lots of woodland skippers, Ochlodes sylvanoides. A great quick-guide to the butterflies of southern Vancouver Island is available. Finally, there are beetles, ants, and some other groups that may visit flowers more or less regularly. Some definitely contribute as pollinators, e.g., the Yellow Velvet Beetle, Lepturobosca chrysocoma (Cerambycidae, Lepturinae), while others may do little for the flower in the return for the treat.
Apart from pollinators, there are a host of other insects which are more or less welcome in a garden. In our garden, one that definitely falls in the latter category is the western subterranean termite (Reticulitermes hesperus). Builders have an annoying habit to bury
leftover wood around construction sites, which in areas with termites is essentially an invitation to the termites to move in. We have annual nuptial emergence events from our backyard lawn, and I have spent about $4,000 and considerable sweat equity to replace a retaining wall and a privacy screen fence which were close to falling down due to these little cellulose-consuming fiends.
Also in the Order Hymenoptera along with bees and wasps, ants are of course ever present. While I have only observed them casually, usually as we dig up a nest when planting something, we have a number of species from several genera in the subfamily Formicinae (Formica and Lasius spp.), a few in the Myrmicinae, (likely Myrmica and or Leptothorax spp.), and one species in the Dolichoderinae. This is the diminutive but pesky odorous house ant, Tapinoma sessile, a native ant that is a frequent home invader, widely distributed, and invasive in Hawaii (unfortunately a hotbed of exotic invaders; see my blog “A naturalist in Hawaii Part III: Attack by the aliens”).
Speaking of invasives, there is no shortage of exotic species in Nanaimo gardens. Some of the most obvious ones are the European paper wasp, Polistes dominula, which most non-biologists would simply call a yellowjacket wasp. These somewhat delicate and (fortunately) relatively non-aggressive wasps build open paper nests in any protected spot they can fine, e.g., my bat house. Another alien that shows up almost wherever you look is the European earwig, Forficula auricularia. While they can be a bit of a nuisance, these insects are actually quite interesting. They are thigmotactic (seek out tight cracks etc.), which led to the idea that they like to crawl into people’s ears, which may explain the odd common name. They have unique hind wings, which are normally folded under the tegmina (=leathery wing covers), which are modified forewings with the same function as the elytra of beetles. Earwig cerci have been modified as pincers, which they can use in defense, male dominance contests, to capture prey, and to help fold the wings. You can tell the sex of an earwig by looking at the pincers; females have relatively straight cerci, whereas in males they are curved.
One of my favourite exotics is the European wool carder bee, Anthidium manicatum. This
member of the Family Megachilidae (leafcutter and mason bees) is rather entertaining as males patrol their favourite patch of flowers such as lamb’s ear, Stachys byzantina, chasing away anything that attempts to land. Lamb’s ear has very hairy leaves, and female wool carder bees collect the hairs to line their nests, which they establish in pre-existing cavities.
A number of beetle species are also exotics. Examples are Rhagonycha fulva (Cantharidae), an introduced soldier beetle from Europe, and Pterostichus melanarius, possibly the most common of all ground beetles, at least in urban and suburban areas. These species are fairly benign, but some new exotics that may cause severe economic damage are on their way, unfortunately. The brown marmorated stink bug, Halyomorpha halys, which has already arrived, and the spotted wing Drosophila, Drosophila suzukii, which is present in the Okanagan, have the potential to severely impact fruit and berry production on Vancouver Island. The stink bug, which is already established on the mainland and has been found on Vancouver Island, is also a significant nuisance insect where it has established in eastern North America. Also, a nest of the giant Asian hornet, Vespa mandarinia, was detected and destroyed recently in Nanaimo. If this species becomes established in BC, it could be very bad news for people and honey bees alike! Among intentially introduced exotics, the Cinnabar moth, Tyria jacobaeae, a biologial control agent of tansy ragwort, Jacobaea vulgaris, is eye-catching as both larvae and adults display aposematic colours. It also has the distinction of having given Cinnabar Valley its name!
I could go on for much longer, but I hope you get the gist – we have a lot of biodiversity right here in our backyard! If you pay attention, you are likely to find a lot more than you thought where you live! Start exploring the little creatures that run the world in addition to the charismatic (but species poor) megafauna!
Bertone, M.A., M. Leong, K.M. Bayless, T.L.F. Malow, R.R. Dunn, and M.D. Trautwein. 2016. Arthropods of the great indoors: characterizing diversity inside urban and suburban homes. PeerJ 4:e1582 https://doi.org/10.7717/peerj.1582
Forbes, A.A., R.K. Bagley, M.A. Beer, A.C. Hippee and H.A. Widmayer . 2018. Quantifying the unquantifiable: why Hymenoptera, not Coleoptera, is the most speciose animal order. BMC Ecology 18: 21, 11 pages https://doi.org/10.1186/s12898-018-0176-x
Larsen, B.B., E.C. Miller, M.K. Rhodes, and J.J. Wiens. 2017. Inordinate fondness multiplied and redistributed: the number of species on earth and the new pie of life. The Quarterly Review of Biology 92: 229-265.
Mora, C., D.P. Tittensor, S. Adl, A.G.B. Simpson, and B. Worm. 2011. How many species are there on earth and in the ocean? PLoS Biology 9(8): e1001127. https://doi.org/10.1371/journal.pbio.1001127
Sheffield, C.S. and J.M. Heron. 2018. The bees of British Columbia (Hymenoptera: Apoidea, Apiformes). Journal of the Entomological Society of British Columbia 115: 44-85. https://journal.entsocbc.ca/index.php/journal/article/view/1001/1097
Stork, N.E. 2018. How many species of insects and other terrestrial arthropods are there on earth? Annual Review of Entomology 63: 31 -45.
Wilson, E.O., 1992. The effects of complex social life on evolution andbiodiversity. Oikos 63: 13–18.