Miniature Lives: Identifying Insects in Your Home and Garden

By Michelle Gleeson

We can’t avoid insects. They scurry past us in the kitchen, pop up in our gardens, or are presented to us in jars by inquisitive children. Despite encountering them on a daily basis, most people don’t know an aphid from an antlion, and identifying an insect using field guides or internet searches can be daunting.

Miniature Lives provides a range of simple strategies that people can use to identify and learn more about the insects in their homes and gardens. Featuring a step-by-step, illustrated identification key and detailed illustrations and colour photographs, the book guides the reader through the basics of entomology (the study of insects). Simple explanations, amusing analogies and quirky facts describe where insects live, how they grow and protect themselves, the clues they leave behind and their status as friend or foe in a way that is both interesting and easy to understand.

Gardeners, nature lovers, students, teachers, and parents and grandparents of bug-crazed kids will love this comprehensive guide to the marvellous diversity of insects that surrounds us and the miniature lives they lead.

• Language: English
• Publisher: CSIRO PUBLISHING
• Release date: Mar 1, 2016
• ISBN: 9781486301393

Book preview

1

Introduction

Why I wrote this book

If I had a dollar for every insect I have been asked to identify, I would be writing this book perched on the deck of a luxury yacht cruising the islands of the Whitsundays and not, sadly, in the cluttered, cold office under my house. The truth is that there are a lot of insects out there, we encounter them on a daily basis, and most people don’t know an aphid from an antlion.

All around Australia, inquisitive kids are chasing and catching insects. Bewildered parents are peering into bug-catchers and sheepishly admitting, ‘Sorry Jimmy, I’m not sure what it is.’ Many teachers are presented with jam jars and lunchboxes crammed with creepy-crawlies and are not quite sure if they are friend or foe.

Keen gardeners, bush restoration volunteers and just about anybody who has tried starting their own veggie patch has encountered many different types of insects. But just what is defoliating your gardenias, leaving strange lumps and bumps on your wattles, or making a meal out of your basil? On the other hand, which beneficial insects do we want to encourage into our gardens to help pollinate our plants or wage war against pests?

Being able to identify an insect you have found in and around your house (not just your garden) has benefits. It allows us to assess the relative amiability or hostility of a given bug, helping us to decide whether to share our space with it or eject it. With the appropriate background knowledge you, too, can solve the mysteries I face daily, including ‘Who has been chewing holes in my cashew nuts?’ or ‘What has been laying eggs on the eaves of my house?’ More excitingly, if you can identify insects you can gain insight into the marvellous diversity of creatures that surrounds us and the miniature lives they lead.

Trying to identify one of our six-legged companions can be daunting (yes, insects do have six legs – but don’t worry, we will get to that shortly). You can spend an hour trawling through a field guide trying to match pictures and still not find what you are looking for. The internet is a minefield for incorrectly identified pictures, dubious ‘fact sheets’ and random pop-up windows for termite control and head lice shampoos.

So here it is, the answer to your prayers – a simple, comprehensive, easy-to-read, identification guide to Australian insects that can be used without needing a microscope, a dictionary of scientific terms or a degree in entomology, which is the technical name for the study of insects. Not only will you be able to identify a given insect but you will also learn what it eats, how it grows, how it protects itself against predators and if it is potentially dangerous or beneficial.

This book is designed as a launch pad for a journey of discovery into the fascinating world of insects. I structured it to be a great starting-point for anyone who is interested in learning more about insect biology and identification. The chapters are chock-full of other useful resources, such as books and keywords for internet searches, to fuel your quest for knowledge.

Mottled katydid (Ephippitytha trigintiduoguttata).

This book has been specifically designed for anyone to pick up and use, no matter what their level of expertise or where they live in Australia. Gardeners, nature lovers, science or biology students, teachers, parents and grandparents of bug-crazed kids can use this book to identify insects in their home or garden.

Approaches to identifying insects

Different approaches can be taken to identify an insect (this does not generally include lifting your shoe and examining the remains of what just ran past you on the bathroom floor – whole specimens are preferable).

Morphology – what insects look like

The first and most obvious way to identify an insect is based on what it looks like. Is it long and leggy, furry and frumpy, or dainty and delicate? Many insects have gauzy wings resembling delicate lace curtains. Others have chunky legs shaped like a chicken drumstick that are used for jumping. Some even have mouthparts like children’s party blowers, for sucking up liquid. By closely examining these weird and wonderful body parts, you may be able to solve the mystery surrounding an insect’s identity.

Habitat – where insects live and occur

Some insects are loyal to a particular habitat – the location where an insect naturally lives, feeds or otherwise typically occurs. For example, whirligig beetles live on the water’s surface in freshwater creeks and ponds. The caterpillars of certain butterflies only eat the leaves of a single type of plant. Some insects are even attracted by human activities – male rhinoceros beetles in eastern Australia are often found battling each other under the bright lights at service stations on warm summer nights. Becoming familiar with an insect’s feeding habits and living arrangements is another approach that can be used to uncover its identity.

Clever clues – the strange structures and evidence that insects leave behind

Some insects operate under the cover of darkness or remain hidden in secret lairs, so cannot be identified based on what they look like. Many are masters of disguise and go undetected, while others are so small that we don’t realise they are there. A few insects are so strange in appearance that we fail to recognise them as living creatures. Nevertheless, they may well leave behind clues that are more obvious to us. With the right approach, we can learn to interpret these clues and use them to deduce what insect is in the vicinity, and maybe even track it down. Weird egg cases, furry cocoons, and lumps, bumps and bite marks on leaves can all be used to identify an insect that eludes our perception.

Scientists use the word ‘cryptic’ to describe the behaviour or appearance of some insects. This means that they are hidden, secretive or diffi cult to detect.

How to use this book

Choose an approach to identify your insect

This book allows you to choose, from the approaches above, the most effective way to identify an insect (or its traces) you find in your home or garden. All chapters tie together, so if you are unable to identify an insect using one approach, you can try a different one (Fig. 1.1). For example, you might find an insect crawling on the footpath or wriggling about on the roof of a car. It is unlikely that the insect lives there, so instead of trying to identify it by focusing on its habitat (Chapter 4), head straight to the chapter of this book that deals with morphology (Chapter 3). See Fig. 1.1 for some guidelines.

Learn the basics

Don’t know an abdomen from an antenna? Having trouble telling insects apart from other creepy-crawlies? Fear not! ‘Insect basics’ (Chapter 2) guides you through body parts, classification, lifecycles and other handy information. I strongly recommend you read that chapter first, to arm you with background information you will need to navigate through this book. At the back of the book there is a Glossary which serves as a quick reference to help you understand any unfamiliar words, and a Pronunciation Guide to help you say them like an entomologist.

What you will find in this book

With over 60 000 described species of insects in Australia, it is very difficult to choose which ones to include in an identification book such as this. Instead of giving you a precise guide to a particular insect species, this book allows you to sort insects into major groups. The insects in each group share many features, including body shape, mode of feeding and means for growth and reproduction, and each such group is called an Order (see pp. 12–13). Information pages on each insect Order are provided in Chapter 6, including details on their general appearance, lifecycle, biology and some amazing facts to wow unsuspecting dinner guests, as well as colour photographs of commonly encountered species as examples.

Fig. 1.1: Choose an approach to identify your insect.

What you will not find in this book

This book allows you to identify the large, easy to see and commonly encountered Orders of insects (18 Orders). Insect Orders whose members are difficult to see with the naked eye, are very uncommon or live where you are unlikely to encounter them, are not included in this book. See Table 2.7 (pp. 19–20) for a list of them.

Not every creepy-crawly you find in your home or garden is an insect. Chapter 2 helps you to distinguish insects from their close relatives such as spiders and centipedes, creatures I refer to as non-insect arthropods. See the end of Chapter 6 for a bit more information about those.

Encouragement for beginners

Insect diversity is immense, and identifying insects can initially be daunting to the beginner. But don’t despair. Once you have worked out what one particular unknown insect is, you have a reference point. Your newfound knowledge makes the next one easier to identify. And once you know that one, you are on the way to building a picture of the insect world. It gets easier as you go. Although there are some real puzzles out there, working hard to crack them (perhaps by using the further reading lists and other sources of information in this book) helps to make it all that much more interesting.

2

Insect basics

This chapter will bring you up to speed with things you need to know about insects, including how to tell them apart from other creepy-crawlies, how we name and group them, how their bodies are designed and the ways in which they grow and change throughout their life.

What is an insect?

Most people unceremoniously label anything with more than four legs a ‘bug’. But it is a lot more interesting than that and if you are familiar with a little tricky terminology it will help you work out what you are looking at. The information below and the diagram (Fig. 2.1) should help you to understand exactly what an insect is and how it differs from other organisms.

Insects are invertebrates, that is, an animal that lacks a spine. Invertebrates are a large group that includes many familiar animals such as insects, worms, snails, crabs, leeches and jellyfish. One of the largest and most diverse groups of invertebrates is the arthropods (to which insects belong). Arthropods have a hard outer shell known as an exoskeleton. Slippery and slimy invertebrates mostly lack an exoskeleton, are not arthropods and do not feature in this book. Of course some exceptions do occur, including cherry slugs (the immature stages of a type of wasp, see Chapter 6, p. 186), and these oddballs make insect diversity even more interesting. Arthropods usually have jointed legs to help with locomotion. Insects, spiders, scorpions, millipedes, crayfish and ticks are all examples of arthropods.

Arthropods are further divided into several different groups, based on how many legs they have. Insects form one such group and have the following traits: six legs, three distinct body parts (the head, thorax and abdomen) and a single pair of antennae. Chapter 6 (p. 297) provides a brief summary of some non-insect arthropods we commonly encounter in our homes and gardens.

You may come across the word ‘minibeast’ in insect books and documentaries and on websites. This is a non-scientific term that is often used to cover any small critters that we see in our homes and garden. While some people use the term minibeast as a substitute for arthropod, others lump other invertebrates such as snails, slugs, leeches and worms under the title.

How many insects are there?

Insects are the most dominant group of organisms on our planet. They account for ~60% of all the species of plants and animals that have been described to date. Well over a million species have been formally named; however, entomologists predict there could be anywhere between 2 million and 50 million extra out there, awaiting discovery. Scientists estimate that at any given time, there are around 10 quintillion individual insects scuttling around our planet. In case you were wondering, that looks like this: 10 000 000 000 000 000 000! In fact, for every person on Earth (around 7 billion) there are around 150 million insects. Some are very common and others are on the brink of extinction.

This display of Christmas beetles (of which there are 35 species in Australia alone) illustrates the strength of insects in both their numbers and diversity.

Bugs versus true bugs

The word ‘bug’ is used by many as a substitute for ‘insect’, including myself from time to time! But a true bug belongs to a special Order of insects with piercing and sucking mouthparts, known as Hemiptera (Chapter 6, p. 274). So all ‘bugs’ are insects, but not all insects are ‘bugs’.

Like all true bugs, this juvenile bee killer assassin bug (Pristhesancus plagipennis) has piercing and sucking mouthparts.

Insect body parts

Identifying insects requires some basic knowledge of their morphology, that is, the structure of their body. This section outlines the basic body parts of an insect (see Table 2.1 and Fig. 2.2). Insect groups have different variations of these basic body parts. This allows them to exploit certain habitats and food types, and this is discussed in the information page for each specific Order (Chapter 6).

Types of insect antennae

The shape and size of insect antennae is highly variable. Entomology textbooks have specific names (usually Latin in origin) for the different types of insect antennae. For example, pectinate antennae have segments shaped like the teeth in a comb, moniliform antennae resemble a string of beads. The figures in Table 2.2 avoid tricky terminology and instead highlight the overall shape of the antennae and their length in relation to the rest of the body. These terms are used throughout the book to describe and compare the antennae of insects in different Orders.

Types of insect mouthparts

Insects have modifications to their mouthparts to enable them to exploit different food sources. Strong jaws help to cut and crush food, while needle-like syringes, squishy sponges and curly drinking straws help insects to feed on liquids. Table 2.3 shows simplified diagrams of different insect mouthparts and outlines the modes of feeding of some common insects.

Fig. 2.1: Classification of insects and their relatives.

Table 2.1. Insect body parts

Fig. 2.2: Basic body parts of an insect.

Fig. 2.3: Close-up of an insect’s antenna.

Fig. 2.4: Some basic parts of an insect’s head.

Fig. 2.5: Some basic parts of an insect’s abdomen.

Types of insect wings

Insects demonstrate a variety of wing designs and modifications to enable them to move about in different habitats. Hardened wing covers protect delicate hind wings for a life underground or underwater; some insect groups have ditched their hind wings to improve speed and manoeuvrability. Table 2.4 shows some different types of insect wings.

Taxonomy – how insects are named

Scientists classify insects and give them long names, but there is a good reason for this. The long names are unique and give us a way in which to group insects, first into a small group of very similar insects, then into bigger groups that are somewhat more diverse but still have features in common. This system is taxonomy, the scientific practice of classifying, identifying and naming organisms.

Table 2.2. Some types of insect antennae

* ‘Mantids’ is commonly used as a plural for ‘mantis’.

All of the world’s animals are classified according to the Linnaean system, developed by a famous Swedish naturalist, Carolus Linnaeus, in 1758. His hierarchical system consists of seven main categories, known as taxa, which are ranked in order of increasing specificity. These taxa are sometimes divided into more specific groups, for example, Subphyla, Superfamilies, Subspecies etc. This system allocates two names to every described animal – the generic name (Genus) and the more specific name (Species). For example, the scientific name for the Cairns birdwing butterfly is Ornithoptera euphorion. Table 2.5 gives an example of how this butterfly would typically be classified.

Insect Orders – how insects are grouped

Insects are divided into various Orders – that is, groups of insects that share features including body shape, mode of feeding and means for growth and reproduction. All insects fall into one of around 30 Orders. You will be familiar with some of these – for example, beetles belong to one Order, cockroaches to another. This section outlines the features of the insect Orders most commonly encountered in your home and garden, and introduces you to some obscure Orders not covered in this book.

Table 2.3. Some types of insect mouthparts

Table 2.4. Some types of insect wings

Insect Orders and their features

Table 2.6 helps you recognise the defining features of 18 most commonly encountered insect Orders in Australia. The silhouette pictures highlight the key features of the adults while at rest (i.e. the posture in which you would most commonly see them around your home or garden). A summary of their main diagnostic features is listed and these traits are generally visible to the naked eye. Be sure to check Tables 2.1–2.4 again if you are unsure of any of the terms used.

Table 2.6 summarises the features of adult insects only. Juvenile insects may be quite different in appearance. The next section explains in detail the way in which young insects grow, develop and differ from adults. In general, insects that undergo incomplete metamorphosis usually resemble the adults in their basic body shape, but lack wings. For these insects, the figures in Table 2.6 are useful in identifying characteristic features, such as their basic body silhouette and the shape of their legs and antennae. Insects that undergo complete metamorphosis start life as grub-like creatures that share few to no features with the adults. To learn more about these insects, refer to ‘Maggots, grubs and caterpillars’ (Chapter 3, p. 64).

Cairns birdwing butterfly (Ornithoptera euphorion). Source: A. Hiller.

Scientists use the term ‘sp.’ as an abbreviation of ‘species’ when they’re referring to only one species. They use the abbreviation ‘spp.’ as a plural for more than one species. For ease of reading, we’ve used ‘sp.’ throughout this book to refer to any number of species.

Table 2.5. Classification of a Cairns birdwing butterfly

Table 2.6. Insect Orders and their features