Garden Nerd Series: Good Bugs in Your Garden
The Garden Nerd series will look at gardening issues in New Westminster. Suggestions for topics, guest submissions, and questions are all welcome. We’ll try and address it all! You can find other posts, as they are added, by clicking here.
Today’s post is written by Jennifer Heron, aka The Bug Lady. After graduating from the University of British Columbia’s biology department, Jennifer’s affinity for insect and bugs lead her to pursue a graduate degree in entomology from the UBC department of Zoology. She is also the operator of The Bug Lab, here in New Westminster, and is available for professional consulting and educational talks as well. This article is excellent for sharing with your kids – there are tonnes of links you can click on which will open new windows, and at the end is a fairly extensive resource list for more information.
Good Bugs in Your Garden
A diverse world of insects, spiders, snails and slugs, earthworms and related animals inhabits urban gardens. Collectively these animals are referred to as bugs, although to an entomologist a bug is a specific order of insect. To summarize, insects have six legs, spiders have eight legs, millipedes and centipedes have many legs and earthworms have none.
British Columbia’s ecosystems are home to an estimated 30,000 – 40,000 different species of insects, most of which we know little about their life cycles, habitats and behaviors. Greater than a quarter of these species have not been described by science. In urban environments there are also many non-native species (also called alien species), which have been accidentally or intentionally introduced to our province from another country or whose geographic ranges have expanded into our province in the last hundred years. Examples of introduced species include the European Chafer Beetle, Harlequin Lady Beetle, Grovesnail and all the earthworms in your garden.
The diversity of insects (and other bugs) in your garden depends on many factors including plants and vegetation, aspect, slope of land, type of soil, moisture and seepage, age of your garden and proximity to natural or wild areas. Insects have efficient reproduction strategies, produce large quantities of eggs and have short life cycles thus enabling a species to have multiple generations during the summer months. In general, pest species are able to reproduce quickly and exploit their resource fast, and by sheer numbers they are able to outcomplete other species (in the short term). I think it’s important to properly identify an insect (to species) because the natural history between species is vastly different, even from within the same group.
To me, all bugs are good, but I acknowledge that other people may hold differing opinions. I think it’s a matter of knowing a bit about a bug’s life cycle and habitat needs, and understanding that you can manipulate some of the bug populations in your garden. The following are insect groups commonly found in urban gardens.
Lady Beetles (also called Ladybugs, Ladybird beetles, Coccinellids) are quite diverse in our province, with over seventy-five species. These insects are voracious predators and will consume vast quantities of aphids and other soft-bodied insects and thus lady beetles are often promoted as natural biological control agents of unwanted insects in your garden. Yet lady beetles are not specific about what insects they eat. Store-bought lady beetles often disperse immediately upon release, and are unlikely to stay in your garden for long. It’s best to encourage natural colonization in your garden. A recommendation written in the book Garden Bugs of British Columbia is best quoted:
“Provide many different plants in your yard (lady beetles will feed on nectar and pollen in the absence of aphid prey). Southern (Harlequin) Lady Beetles [also called the Multi-coloured Asian Lady Beetle] will attack other lady beetles, lacewings, hoverflies and even butterflies, if aphids are scarce. This species was introduced to Washington State in the 1920′s as an aphid predator and is now the most common species in south coastal British Columbia. As a result of competition, several native lady beetle species are in decline or have become displaced from their native habitats. This species is the most common invader of homes in autumn.”
For more information common lady beetles refer to Lady Beetles of Ontario (although an Ontario website, there are the some of the same species in British Columbia).
Pollinators are insects that pollinate plants and include bees, wasps, flies, butterflies, moths and some beetle groups. In recent years scientists have raised attention to the global decline of insect pollinators and the significant contribution these insect groups make to plant health. The worldwide economic value of pollination services is US $217 billion!
A healthy and diverse backyard garden thrives when there is a healthy and diverse complement of insect pollinators. Pollinators are the necessary link that enables plants to reproduce, and thus a keystone to human food and health. Because pollinators are globally declining, it is vital to encourage pollinators into urban parks, gardens and backyards.
Butterflies and moths are noticeable insect pollinators with large and often colourful wings. There are greater than 180 butterflies and 2100 moths living in British Columbia’s ecosystems. In the lower mainland there is an estimated 60 species of butterflies and unknown number of moths (in the hundreds). Butterfly species groups commonly observed in your backyard include swallowtails, blues, sulphurs, and skippers. Specific species include painted lady, western tiger swallowtail and Lorquin’s Admiral. Cabbage white is also a commonly observed butterfly although the caterpillars are known to cause damage to plants in the cabbage family (cabbages, kale, broccoli, cauliflower, etc.).
Wasps are important garden pollinators. Wasps include social insects such as bald-faced hornets, paper wasps and yellow jackets however this insect group is incredibly diverse and most species are solitary insects that rarely sting. Wasps are typically predators and consume other small insects. However, wasps also drink flower nectar and hunt among flowers for the same insects that are attracted to flower nectar. Other wasp species groups include Ichneumonid wasps and digger wasps. Wasp species that damage plants include gall wasps (more general information found here).
Flies are one of the most diverse groups in our gardens; often so small one may not notice these insects. Flies may have similar markings to wasps and thus it’s easy to confuse the two groups, however flies have two wings and wasps have four wings. The most common flies seen in your garden are Bee Flies (or Bomyliid flies) and Hover Flies (or Syrphid flies).
Bees are among the most important pollinators in your garden. There are hundreds of native species in British Columbia, although the species diversity is not fully known. Some of most noticeable bee groups include honeybees, bumblebees, mason bees, and leafcutter bees. Common species you may see in your garden include Blue Orchard Mason Bee and Alfalfa Leafcutter Bee. Comparing honeybees with other bees is explained well on the B.C. Cranberry Growers website.
Beetles are the largest and most diverse insect group and live in all habitat types in your garden. Because these insects are typically large, slow and have hard outer body surfaces, they are more readily seen that faster flying insects. Beetle groups commonly seen in your garden include carabids, longhorn beetles, weevils and lady beetles. Carabids are predatory ground beetles and will feed upon slugs and snails. Longhorn beetles have long thin antennae and will often sit atop large flowers, although you will also find them in all garden habitats. Weevils are characterized by their long snout and will also sit upon leafy vegetation.
In urban gardens there is actually a lot more bug diversity than one may expect. There are many bug groups I have not included in this summary, including worms, slugs and snails, spiders, centipedes and millipedes, earwigs, dragonflies, grasshoppers, pillbugs and ants. Take the time this summer to photograph some of the bugs you see in your garden. It’s a great way to familiarize yourself with nature and can provide endless entertainment (at least for a bug geek like me). The best time to photograph insects is in the morning before the sun is high. Insects rely on temperature for movement and in the dewy morning an insect is not able to move fast. Also, misting an insect with a light spray from a bottle will also allow you to photograph the insect easier (the mist slows the insect down).
Whatever your approach to the insects in your garden, remember that they all serve an important purpose in nature. Encourage beneficial insects to your garden through planting native plants, which in turn attract native insects. Understanding habitats needed for butterflies will help with creating a backyard butterfly garden. A good book is Butterfly Gardening: Creating Summer Magic in Your Garden by the Xerces Society (although this covers all of North America). Limit the quantity and concentration of pesticides you spray in your garden and if possible, don’t apply pesticides at all. Create a garden with a diversity of plants, limit monocultures, allow leaves and woody debris to pile up, create a compost, provide horizontal and vertical plant structure (eg. moss, herbs, shrubs, deciduous and evergreen trees) and provide sites with mud, rock, pebbles and gravel.
A colleague of mine has been moth trapping in his backyard for a number of years (he lives in Coquitlam), and each summer he adds more species to his growing list. During his trapping he’s likely found a few new species to science (only a few people in Canada have the skills to describe new moth species to science), new records of native species and greater than ten new introduced moths to British Columbia including a new record to North America. This shows there are many species yet to discovered and recorded and one never knows what new insect they may find, even in their own backyard.
Reference books for bug identification
- The Butterflies of Canada. 1998. Written by R. A. Layberry, P.W.Hall and J.D.Lafontaine. University of Toronto Press.
- Butterflies of Cascadia. 2003. Written by Robert Pyle. Seattle Audobon Society
- Butterflies of British Columbia. 2001. Written by Crispin Guppy and Jon Shepard. Royal BC Museum and UBC Press.
- Bugs of British Columbia. 2001. Written by J. Acorn and I. Sheldon. Lone Pine Publishing
- Butterflies of British Columbia. 2006. Written by J. Acorn and I. Sheldon. Lone Pine Publishing.
- Introducing the Dragonflies of British Columbia and the Yukon. 2002. Written by Robert A. Cannings. Published by Royal B.C. Museum.
- Ladybugs of Alberta. 2007. Written by John Acorn. Published by University of Alberta Press. Although this book is on Alberta lady beetles, many of these same species also live in British Columbia.
- Landsnails of British Columbia. 2004. Written by R. Forsyth. Published by the Royal B.C. Museum. Also includes slugs and introduced species
- Tiger Beetles of Alberta. 2000. Written by John Acorn. Published by University of Alberta Press. Although this book is on Alberta tiger beetles, many of these same species also live in British Columbia. There are approximately 20 species of Tiger Beetles in BC, and once you learn a bit about this species group you will be hooked!
- Insects of the Pacific Northwest. Written by Peter Haggard and Judy Haggard. Timber Press.
- Insects and their Natural History. Written by Stephen A. Marshall – this is a large book, and a little more expensive than the average field guide. Yet the book provides for endless reading and enjoyment and is invaluable for helping to identify insect species’ groups.
- Garden Bugs of British Columbia. 2008. Written by Janice Elmhirst, Ken Fry and Doug Macaulay. Lone Pine Publishing.
- The Pollinator Conservation Handbook by the Xerces Society. www.xerces.or
- Lepidoptera of the Pacific Northwest: Caterpillars and Adults, written by Jeffrey C. Miller and Paul C. Hammond. Free publication from the U.S. Forest Service. If you email firstname.lastname@example.org, if there are still copies, you can request one be sent to you.
- Conifer Defoliators of British Columbia, written by Robert W. Duncan and produced by the Canadian Forest Service. This is also a free publication and if you phone the Pacific Forestry Centre (Victoria) at 250-363-0600 they can help you.
- Exotic Forest Insect Guidebook, by Troy Kimoto and Marnie Duthie-Holt. If you call 1-800-442-2342 you can request a copy be sent to you. The publication is also available online at www.inspection.gc.ca
- Pollination Canada www.seeds.ca 1-866-509-SEED; email@example.com.
- E-Fauna B.C. Electronic Atlas of the Wildlife of British Columbia www.efauna.bc.ca
- E-Flora B.C. Electronic Atlas of the Plants of British Columbia www.eflora.bc.ca
- Invasive Plant Council of BC www.invasiveplantcouncilbc.ca
- Landsnails and Slugs of Canada www.mollus.ca/rforsyth/index.html
- BC Conservation Data Centre Species and Ecosystems Explorer, then click on the link to “Launch BC Species and Ecosystems Explorer”.
- Beneficial Insects of British Columbia Cranberry Bogs http://www.direct.ca/pestpage/ben3.html
- Xerces Society for Invertebrate Conservation www.xerces.org
- Canadian Biodiversity Information Facility Butterflies of Canada http://www.cbif.gc.ca/spp_pages/butterflies/index_e.php
- Apiculture – Bees and Pollinators, B.C. Ministry of Agriculture http://www.agf.gov.bc.ca/apiculture/index.htm