Unexpected House Pests

Yikes! There's something on crawling on your houseplants! In her first post of 2017, Jean Godawa tackles the subject of unexpected and unwelcome visitors that seem to appear out of nowhere.

Before the middle of the 17th century, people believed that some animals could spontaneously generate under the right conditions. According to the wisdom of the time, you could make a colony of mice simply by putting some dirty rags and a bit of wheat into a barrel. Likewise, if you left a carcass of meat hanging, you could create a swarm of flies. The idea that the right conditions just attract these creatures from somewhere else was not even considered. We know better now thanks to science and experimentation.

But if you've ever had a fittonia in your house develop mealy bugs, seemingly out of nowhere, you might start to understand that 17th century mid-set. If you keep your plants indoors, you shouldn't have to think about insects, should you?

Unfortunately, indoor plants are just as susceptible to certain pests as their outdoor counterparts, but not by spontaneous generation. Introducing new plants into your home, leaving windows open, putting houseplants outside during good weather are all invitations for unwanted pests.

A favourite meal to ladybugs, aphids (Aphididae) are not just pests of outdoor plants. These tiny (approx. 4 to 8 mm) bugs are easy to recognize with their pear shape and two short, stick-like cornicles near their backside. Aphids can have both winged and wingless forms and vary in colour depending on the species.

In their winged form, they can fly into your home and lay eggs on your houseplants. Aphids can also hide on fruits and vegetables at the grocery store where they have unlimited food and no predators. If you bring home any produce, even with a single aphid on it, your houseplants could soon be covered in the pests. Aphids are one of the few insects that are capable of parthenogenesis. That is, they can reproduce without mating.

These creatures use a short, beak-like mouth to pierce plant leaves or shoots and suck out the fluid. They excrete a clear, sticky substance called honeydew, which can often invite mold growth. Because of the way they feed, aphids are also capable of transmitting plant viruses from one plant to another.

Typically, a few aphids on a healthy houseplant won't kill it but they can become a problem if you don't intervene. If your houseplant is a sturdy one, take it outside and knock off the aphids with a forceful blast of water from the hose. For more delicate houseplants, treat aphids with an insecticidal soap or horticultural oil.

If your houseplants start to develop a cottony white substance on the underside of leaves or on the stems, take a closer look. That white mass could be a group of plant sucking mealybugs (Pseudococcidae). These creatures are elongated, oval bugs coated with a waxy secretion and are common pests of houseplants.

Mealybugs can be difficult to control because they spread easily. Being so small, they can crawl undetected from one plant to another or can be transferred by a slight breeze. The waxy coating protects the bugs from too much or too little moisture as well as from insecticidal sprays.

When introducing a new plant to the home, keep it quarantined, away from your other houseplants, for a couple of months to make sure it's healthy and pest free. For small infestations, pick the bugs off by hand or use a cotton swab dipped in rubbing alcohol to remove them. A small paintbrush dipped in mild dish soap can also help knock mealybugs off your plants. Unfortunately, you may need to discard a heavily infested houseplant to protect your other plants.

Another common houseplant and greenhouse pest is the whitefly (Aleyrodidae). At 2 to 3 mm long, this tiny pest can still cause quite a bit of damage. Like their aphid and mealybug cousins, whiteflies have a needle-like mouth they use to pierce plant tissue and suck out the fluid. Their feeding damages leaves and stems causing yellowing and wilting. The yellowish body and white wings of the whitefly are covered with a white powdery coating. These insects can also transmit plant viruses and can produce honeydew that fosters mold growth.

When immature whiteflies first hatch from their eggs, they crawl to a suitable area of the plant. As they develop, these larvae become oval, flattened and immobile until they pupate into winged adults. Insecticidal soaps are most effective on the immature bugs but will also work to get rid of the adults. Check the underside of leaves for the larvae if you notice whiteflies around your houseplants.

If leaves on your houseplants are dropping off or have yellow spotting (stippling) or webbing, particularly on the undersides, you may have a problem with spider mites (Acarina). These eight-legged creatures, relatives of spiders, may not be visible unless you look very closely, but their damage usually gives them away. Spider mites are another common destructive houseplant pest but they can be treated with insecticidal soap. As with all houseplant pests, it is better for the health of your other plants to discard a heavily infested one.

It would be easy to ignore or overlook scale insects (Coccoidea) as they look nothing like a typical insect. Throughout most of their immature lives, they have no antennae or legs and remain motionless while they feed. They often look like natural knots or bumps on stems. Some scale species are quite useful - shellac comes from a scale insect, as do some red dyes (cochineal). Despite this, many scale species are serious pests to indoor plants, and in large numbers can be very destructive.

While houseplants are typically protected from the multitude of potential pests outside, they are at a bit of a disadvantage indoors. An infested houseplant can't get help from any of the beneficial insects living in the garden. As much as I am fascinated by insects, I can't set a bunch of ladybugs loose in my home to deal with aphids and I'm not about to introduce parasitic wasps into my living room to get rid of scale insects on a ficus.

Our solutions for dealing with pests of indoor plants are more limited. Hand removal, trimming off infested leaves, applying insecticidal soap or horticultural oil can usually take care of most minor houseplant pests. 

The best option, though, is prevention. If you accept clippings from a friend or buy new plants, be sure to quarantine them first. Wash fruits and vegetables well when you bring them inside from the store or garden. If you put your plants outside in warm weather, frequently inspect them for unwanted pests.

If houseplant pests do show up, they could have hatched from eggs in the potting soil or entered through a slight crack around a window. Healthy plants can tolerate a few bugs and as long as you inspect plants often, and treat them early, pests are manageable.

Like mice in a barrel or rats on a ship, bugs don't spontaneously generate on indoor plants. Even though I know this, I am sometimes, very briefly, convinced that fruit flies can magically appear from another dimension. When I'm sure that I've thoroughly washed all the peaches in a basket from the market, those pesky little creatures will still be flying around my kitchen.

(Click this link to find out how to make your own insecticidal soap.)

Post written by Jean Godawa

Jean is a science teacher and writer. She has been writing science-related articles for print and online publications for more than ten years. Jean holds a degree in biology and environmental science with a focus on entomology from the University of Toronto. She has also conducted field research in the tropical rainforests of Asia and South America.

Photo Credits for this post: Many thanks to Leslie Ingram, David Capparet, Jeffery W. Lotz, Charles Olsen, Chazz Hesselein and Ken Sproule for allowing us to use of the photographs in this post.

Nature Books for Gift Giving (Plus a Giveaway)

In this post, Jean Godawa has drawn up a great list of nature book recommendations 

for holiday gift giving.

As a student, I accumulated dozens of books about the natural world. Most have long outlived their usefulness and have been replaced by updated scientific discoveries and the collection of infinite knowledge available on the internet. There are, however, a few books with broken spines, muddy fingerprints and loose pages that are never far from reach at my desk. They continue to serve me twenty years later. Those are the books that I love. Those are the books that are worth the shelf space they occupy. I keep that in mind when looking for gifts for fellow nature lovers and try to select books that they too will find worthy of their own shelf space.

  

Wicked Plants, Wicked Bugs and The Drunken Botanist by Amy Stewart:

Did you know that cashews are from the same botanical family as poison ivy and poison oak? For people of any age who love macabre stories, bestselling author Amy Stewart has written some wonderful books on the intoxicating, destructive, dangerous or deadly properties of plants and insects. The books are well organized and easy to read, with plenty of useful information such as common names, habitats and origins. Her descriptions of historical encounters with some of nature's bizarre flora and fauna is both informative and entertaining. The author and illustrator recently released The Wicked Plants Coloring Book  with "40 botanical atrocities to color and keep". Any or all of these would make great gifts for nature lovers with just a hint of a dark side.

The Curious Nature Guide by Clare Walker Leslie:

We move throughout the day from one place to the next with little regard for the natural world we pass through. Clare Walker Leslie inspires us to follow that old adage of stopping to smell the roses but in a fresh way. This book encourages you to explore your neighbourhood or walk around outside and notice the various elements, from the clouds in the sky to the fungus on a tree trunk. Filled with information and simple activities such a making a spore print from mushroom caps or pressing autumn leaves, this guide would make an excellent gift for nature-loving families with curious children.

Gardening for Butterflies by the Xerces Society:

Stunning photography with detailed information on butterfly biology and behaviour is presented in this book in a very informative and easy to read manner. It suggests suitable plants for a variety of North American regions and provides an alphabetical listing of those plants along with wonderful reference pictures and ideal growing information. If you know someone who is planning or designing a new garden or is just looking for information about plants (including trees) that will attract butterflies to their garden, this book would be a welcome addition to their library.

Garden Flora by Noel Kingsbury:

Noel Kingsbury has written and excellent reference guide on the origins of garden plants. Laid out alphabetically, Garden Flora delves into the heritage of plants and describes, among many other things, how they were crossed with others to give us the plants we use in our gardens today. Visually, the book is gorgeous, with reproductions of historical illustrations, watercolours and paintings as well as contemporary photographs of plant species. This book is well suited to gardeners and botanists who wish to delve further into the history of their current garden flora.

Peterson First Guides by Roger Tory Peterson:

There are so many field guides to help identify the plants and animals around us that it is difficult to know which one to choose. My most well-used guides have always been by Peterson. Whether you want to identify the caterpillar you found on the sidewalk or the bird at your feeder, there is a Peterson guide to help you. The smaller First Guides are a great start for any age and there is one for birds, butterflies, caterpillars and insects.  Any of these field guides would make great stocking-stuffers for nature lovers. 

 

Bee Time by Mark L. Winston and H is for Hawk by Helen Macdonald:

Both award winning books, Bee Time and H is for Hawk, are non-fiction accounts of the authors' personal relationships with nature. In Bee Time, Mark Winston describes his work in apiaries around the world and makes connections between his interactions with bees and with people. Helen Macdonald describes her immersion into the training of a goshawk while shutting out friends and family in order to deal with the death of her father. Both books are beautifully written. Upon finishing them, the reader is left not only with a great deal of knowledge about bees and hawks, but with a new understanding of human nature. If you know someone who is fascinated with nature and those that study it, both of these books would make excellent gifts.

A Child's Introduction to Natural History by Heather Alexander:

For readers aged 8 to 12, Heather Alexander provides a wealth of information about the natural world. The world's biomes are well described along with the living and non-living things contained within them. She introduces kids to the scientists and naturalists who have helped further our knowledge of the natural world. As an added bonus, the book includes patterns and paper for making origami animals.

A Wasp Builds a Nest by Kate Scarborough:

For younger readers, Kate Scarborough has written a book that can be read like a storybook but is full of accurate information on how wasps build their nest. Curious kids who wonder what it looks like inside a wasp nest will get a chance to see exactly what's happening in it at each stage of its development. The book is suitable for young nature lovers aged 5 to 8.

I could happily spend days in the library or bookstore leafing through books on plants or animals or the environment in general. The above are just a few suggestions that I think any nature lover would be pleased to receive. If you have read or used any of these books, I'd love to hear your feedback. Also, if you have any further recommendations for gift books, please do share them.

Blog post by Jean Godawa

About Jean Godawa: Jean is a science teacher and writer. She has been writing science-related articles for print and online publications for more than ten years. Jean holds a degree in biology and environmental science with a focus on entomology from the University of Toronto. She had conducted field research in the tropical rainforests of Asia and South America.

Thomas Allen & Sons has kindly given us a copy of the Garden Flora: The Natural and Cultural History of Plants in Your Garden to give away. Because we will have to send this book through the mail, we will have to limit entry in the draw to readers in Canada and the USA.

Please leave a comment below if you would like to be included in the book draw. The draw will remain open for the until December 1st. 

If you are not a blogger, you can enter to win by leaving a comment on the Three Dogs in a Garden Facebook page. You are also welcome to enter by sending Jennifer an email (jenc_art@hotmail.com).

Please make sure there is a way for us to track down your email address should your name be drawn.

The Sounds of Summer

In her latest post, Jean Godawa writes about cicadas, whose mating call is one of the sounds we  so closely associate with summer.

Labour Day has passed, signalling, for many, the end of summer. But the cicadas in the maple tree outside my window clearly don't follow the same calendar that I do. These insects that are usually associated with the dog days of summer, are still loudly buzzing away.

Cicadas are large, wide-bodied members of the true bug order Hemiptera, growing up to 5 cms (2 inches) long. The most common species in my area, the dog day cicadas (Neotibicen canicularis), certainly live up to their name, being active during the sultry days of July and August.

Despite their size, you are more likely to hear these large creatures than to see them; they spend  most of their short adult lives high in the trees.

Using abdominal muscles and drum-like membranes called tymbals, male cicadas make noise to attract females for mating. The sound can be heard more than a kilometer away and can reach up to 120 decibels; that's louder than the sound produced by a motorcycle or power saw.

After mating, female cicadas lay eggs in small branches that die off and fall to the ground. The immature cicadas (nymphs) burrow into the ground and feed on plant roots for at least 2 to 5 years. We hear these loud insects every summer but the documented broods (numbered I through XIV) have predictable, staggered cycles, some as long as 17 years depending on the species.

Periodical cicadas (Magicicada spp.) have life spans of either 13 or 17 years. They are easily distinguished from other cicada species by their red eyes and reddish wing veins. Brood V emerged this year in the northeastern U.S. and the offspring of this brood won't be seen or heard until 2033. Brood VI will emerge next year in Georgia and the Carolinas. No data is available for the presence of periodical cicadas in Canada, while dog day cicadas, with much shorter life spans, are quite common in Ontario and Quebec.

Carolina locust (Dissosteira carolina)

Periodical cicadas have mistakenly been called 17 year locusts but are completely different from actual locusts, also known as grasshoppers (Orthoptera).

Large groups of cicada nymphs can cause serious damage to young tree roots and in an emerging year, thousands, if not millions of adults laying eggs can damage tree branches. In general though, cicadas are not considered an economically important pest, nor are they dangerous to humans.

When mature, cicada nymphs crawl out of the ground and onto tree trunks where they latch on and molt their exoskeleton to become winged adults.

You can often find these abandoned "shells", or exuviae, in early or mid-July on the ground or at the base of trees. You can see from these, the large, strong front legs that nymphs use to dig through the soil.

Adult cicadas use a straw shaped mouth to siphon sap from trees but they don't eat much and only live for a few weeks as adults, dying off with the summer.

While cicadas may munch on tree roots in our yards, some people advocate using large groups of cicadas to our advantage. They are, according to some scientists, a logical food choice for humans, since they belong to the same group of animals (Arthropods) as shrimp and lobsters. I admit that, in the interest of scientific curiosity, I have eaten insects. Most had kind of a nutty flavour. But I would much rather listen to the cicada song than have one for a snack. As long as I can hear them buzzing, I can be assured that summer is definitely not over yet.


About Jean Godawa: Jean is a science teacher and writer. She has been writing science-related articles for print and online publications for more than ten years. Jean holds a degree in biology and environmental science with a focus on entomology from the University of Toronto. She had conducted field research in the tropical rainforests of Asia and South America.

Many thanks again to photographer Ken Sproule and the wonderful people at bugwood.org for curating such an extensive catalogue of insect photographs.

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Shade, Shells and Slime

In her latest post Jean Godawa writes about slugs and snails. 

I'm lucky to live in a part of the city with many large mature trees. The fall colours on my street rival those of any picturesque country lane. So much so, that visitors and passers-by often stop to take pictures. As grateful as I am for the autumn beauty and summer shade that this canopy provides, I envy gardens filled with blooms of all textures, shapes and colours that only a sunny or partially sunny area can sustain. Thankfully, the previous owner of our home had a talent for creating visual interest with several varieties of hostas which thrive today.

With all those hostas in my Jurassic-looking garden however, comes an open invitation for snails and slugs (Gastropoda). The wide, sturdy leaves and low positioning of hostas make them perfect hosts for these slow moving, shade loving members of the mollusc phylum.

The brown-lipped, or grove snail (Cepaea nemoralis) is an introduced species found in the north eastern U.S. and southern Ontario. It varies in colour and number of stripes with the opening lip of the shell typically dark brown in colour.

The white-lipped snail (Cepaea hortensis) has a light coloured band around the shell opening.

Snails and slugs have two pairs of antennae-like appendages - one small pair is used for smelling while the larger, upper pair holds the eyes.

Gastropods require a moist environment to survive. The common amber snail (Succinea putris) lives near water sources and feeds on strong aquatic reeds and grasses.

You may rarely see these nocturnal creatures but you will know they are around. They feed at night to avoid both predators and the harsh, drying effects of the sun. They spend the day sheltered under the shade of plants, decaying plant matter, mulch or garden structures. A slime trail, along with holes or jagged edges on leaves indicates a snail or slug problem.

Slugs vary in size with some species growing up to 25 cms (10 inches) in length. They can range in colour from light yellow to dark brown or grey. Their feeding behaviour and habitat preference is similar to snails. The obvious difference between the two is the slug's lack of shell.

Most snails and slugs that you encounter in the garden are hermaphrodites, with both male and female reproductive organs. Despite this, they do not self-fertilize - they must mate to reproduce. Eggs are laid in a sticky secretion in a damp protected area of the garden. After about a month, the immature creatures hatch and begin feeding. Warm humid conditions speed up their development.

Being fascinated, as I am, with all kinds of crawly and slimy things, I have a hard time getting rid of creatures that are just doing what is natural. If plants are hardy and growing well, they can usually tolerate a bit of damage from a snail or slug. When pest numbers increase and I start to feel the crunch of shells under my feet as I walk in the yard, then I know it's time to act.

Cleaning up debris around affected plants and trimming off any leaves that touch the ground helps protect plants from snail and slug damage. Remove overturned pots, fallen branches and if you're not squeamish, handpick the creatures off the plant and drop them in a bucket of soapy water. Go out after dark with a flashlight or early in the morning to find and remove the pests.

Barriers, such as copper strips or diatomaceous earth, and traps, with or without bait, can also eliminate snails and slugs. Be sure to check and clean traps frequently at first for the best results.

For every plant we bring into the garden, there will be some creature that needs it for food, shelter or reproduction. Whether it's an owl living in a tree, a deer eating tall lilies or slugs munching on hostas, if we accept that we share our space with many other creatures and we arm ourselves with knowledge about those creatures, then it's easy to maintain healthy, vibrant gardens.

About Jean Godawa: Jean is a science teacher and writer. She has been writing science-related articles for print and online publications for more than ten years. Jean holds a degree in biology and environmental science with a focus on entomology from the University of Toronto. She had conducted field research in the tropical rainforests of Asia and South America.

Many thanks to Ken Sproule for providing the images for this post.

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Silk and Venom

In the third post in her series on garden insects, Jean Godawa writes about the benefits of having spiders in your garden.

To me, the beauty of a garden goes beyond the sensory enjoyment it provides. The vibrant colours, varying textures and fragrant air command our attention, but it is the inner workings of the garden, the things happening regardless of our horticultural skills, that make it a special place, worthy of our awe and appreciation.

Spiders are one of those creatures with a significant role in keeping garden plants healthy and they do this with little to no help from us. By eating the bugs that destroy plants, these eight-legged animals are always on duty as pest control agents.

Orb weaving spiders spin silken webs to attract flying insects. One of the most striking of the orb weavers is the black and yellow garden spider (Argiope aurantia). Although its bright colouring and large size make it look somewhat tropical, this species is quite common in gardens throughout the U.S. and Canada.

The female creates a complicated web that can have a diameter of more than 60 cm or 2 feet. She adds zigzag strips, called stabilimenta to the construction. Despite the name, these structures probably don't help stabilize the web. They are more likely used for attraction of prey or mates, or for warning or camouflage. It costs the spider much energy to produce these intricate patterns so they must provide some advantage. Scientists are still trying to figure it out.

Any flying insect is a potential meal for garden spiders including grasshoppers, aphids, wasps, bees and butterflies.

Some spiders prefer to capture their insect meals by ambush methods rather than expending any silk. Crab spiders (Thomisidae), use their larger front legs to easily grab their prey. Some species can change over time to match the colour of their plant surroundings.

A more active hunter is the jumping spider (Salticidae).These creatures pounce on their insect prey using their sharp vision and nimble movements.

Most spiders only live for one season. They lay eggs, usually inside silken cocoon-like structures. In some species the eggs hatch before winter but the young spiderlings remain protected in the silk until they can disperse in the spring.

Spiders feed by injecting venom into their prey to immobilize it. Digestive fluids liquefy the prey and the spider sucks up the remains. Gruesome as this sounds, most spiders are rarely dangerous to humans. They are more likely to escape your presence than to bite you.

Even an arachnophobic gardener can't deny the benefits of welcoming spiders into the garden. Tall grasses and long stemmed plants provide stable support for orb-weaving spiders to construct their webs. Other spiders prefer the dark damp conditions of thick mulch. If a garden provides these habitats, it can be sure of non-stop, natural pest control from spiders.

About Jean Godawa: Jean is a science teacher and writer. She has been writing science-related articles for print and online publications for more than ten years. Jean holds a degree in biology and environmental science with a focus on entomology from the University of Toronto. She had conducted field research in the tropical rainforests of Asia and South America.

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What's Eating my Lilies?

Understanding the lifecycle of a garden pest is the first line of defence. Knowing how to spot lily beetle eggs, recognizing their rather disgusting looking larvae and having a simple method for eliminating the adults can go along way to having better looking lilies in your garden this summer! In her second post, Jean Godawa tackles the subject of lily beetles.

Lilioceris lilii

Like street lights, stop signs or fire trucks, the bright red colour of lily leaf beetles (Lilioceris lilii) certainly attracts our attention. The beauty of this insect, especially against a leafy green backdrop, becomes irrelevant however, as you see the damage it causes to your lilies.

Lily Beetle Eggs

After spending the winter protected from the elements, adult lily leaf beetles emerge in the spring, coinciding with the emergence of lily plants. They mate then lay orangey-brown lines of eggs on the underside of lily foliage. These pests can lay over 400 eggs in a season.

Lilioceris lilii larva

When the eggs hatch, the orange larvae feed under dark shields of their own excrement. Well protected from predators, the immature insects grow and continue to damage the plant. 

Healthy Lilies

Defoliated lily with buds intact

Several adults and larvae together can completely defoliate the lilies in your garden.

After a few weeks, the larvae drop to the soil where they pupate for a few more weeks then become adults. In the fall, this new generation will seek out shelter or burrow into the soil to overwinter. The cycle begins again in spring.

The best defence against these red nuisances is to destroy them before they have a chance to lay eggs. If you’ve been plagued by lily leaf beetles in the past, keep watch for the emerging adults as soon as your garden starts to wake up in spring.

Hand-pick the beetles off your plants and squish them between your thumb and forefinger. Don’t worry, they won’t bite, but you have to be quick. When disturbed or threatened, the beetles drop to the ground on their backs. The underside of these bright red creatures is black and blends in well with the soil.  

If the thought of squishing bugs is too unpleasant, you can drop them into a bucket of soapy water to destroy them. Where space permits, shake the plant gently over the bucket to get rid of any beetles you can’t see.

If you missed the opportunity to find the adults and there are already gooey black larvae munching away on the plants, you can hand remove those as well. Where several larvae or eggs are infesting a leaf, or if you just can’t bring yourself to squish poop-covered creatures, it might be more effective to just cut the leaf off, if the plant is otherwise healthy and robust.

Lily beetles are not originally from North America so there are no natural predators here to keep the population in check. A tiny parasitic wasp from Europe is being studied as a potential control agent for this introduced species.

We’ve been conditioned to recognize red as a warning colour. Whether by natural design or coincidence, bright red lily leaf beetles warn gardeners that their lilies are in danger.


About Jean Godawa: Jean is a science teacher and writer. She has been writing science-related articles for print and online publications for more than ten years. Jean holds a degree in biology and environmental science with a focus on entomology from the University of Toronto. She had conducted field research in the tropical rainforests of Asia and South America.

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