Caterpillars - Garden Pest of the Month

Caterpillars at a glance

Type of Damage	Chewing
Plant Symptoms	Holes in fruits, missing leaves, eaten leaves, ‘felled’ seedlings
Favourite Plant	Most food crops, especially tomatoes, fruit trees, grapes, citrus, sweet potato, Solanum family
Control	Biological (predators: wasps, mantids, assassin bugs & chickens), else physical removal

Caterpillar morphology

Quick Intro

Caterpillars are regarded as one of the most destructive insect pests that can devastate a food crop overnight! Some are specialists only feeding on certain host plants whereas other are generalists and will feed on anything green. Here I discuss some of the caterpillars that have cause havoc in my garden and listed a few similar species to be on the lookout for.

Science Stuff

Caterpillars are the larval or immature stages of moths and butterflies; these belong to the Lepidoptera order of insects. Sometimes caterpillars are referred to as worms, but they are not true worms (Annelida), such as earthworms.

Caterpillar is a derivative from the Latin words cattus (cat) and pilosus (hairy), which basically translates to hairy cat J. Many caterpillars are indeed hairy, which irritate the skin or mucous membranes of would-be predators. Some are even toxic as they sequester poisons in their bodies from compounds in their host plants. Toxic caterpillars display their toxicity through bright colouration, whereas other relies on camouflage for protection.

Alice and the Caterpillar

Interesting morphological characteristics: the last few segments on the caterpillar’s body have fleshy sucker-like legs, known as prolegs, with which they cling to substrates. They have silk glands, which are modified salivary glands mainly used to produce silk for pupation and cocoon construction.

Habitat & Feeding

Adults (butterflies and moths) are generally nectar feeding, whereas larvae are herbivorous and some species are insectivorous or detrivores.

The main objectives of caterpillars are to feed and grow. They are gregarious and feed in groups to ensure safety. Caterpillars feed on the underside of leaves, so be sure to check there when you are on the hunt. Caterpillars moult several times throughout their life as they grow (4-5 times). Plump caterpillars spin cocoons (silk) or pupate in chrysalis (non-silk). Here they undergo metamorphosis into their final butterfly or moth stage.

Caterpillars occupy a wide variety of environments and many have cosmopolitan distribution, which means you are likely not going to get away from them…

Diseases

Generally caterpillars don’t transmit plant diseases, but secondary bacterial, fungal or virus infections can set into affected sites which, have been eaten or stung (fruits and leaves). Holes eaten in fruits can become homes for other insects as well!

Citrus Swallowtail Butterfly, Papilio demodocus

Caterpillars of this family have large, striking butterflies of the Papilionidae family more commonly known as the Swallowtails. They have several district immature stages with different appearances, but all feed on citrus or members of the Rutaceae plant family (lemons, oranges and rue include a few).

Early stage caterpillars are black and spiny with white or orange patterns, this gives them a bird-dropping characteristic. Larger caterpillars lose these markings and become green with the classic swallowtail morphology; large eyespots on the head and thick fleshy body. All stages have a specialised scent gland (technical term, osmeterium) which is concealed behind the head and used as a defence mechanism. When disturbed they whip it out and try to stink you away! They pupate in chrysalis suspended by silk threads.

I had several infestations, they seem to come in waves, over the course of summer. They feed on any Rutaceae plant member, since I found them on my lemons, limes and curry plant!

Citrus swallowtail caterpillar two immatures,
Papillio demodocus

Citrus swallowtail caterpillar,
Papillio demodocus

Citrus swallowtail caterpillar osmeterium,
Papillio demodocus

Citrus swallowtail butterfly,
Papillio demodocus

Citrus swallowtail butterfly,
Papillio demodocus

Similar species in South Africa:

Mocker swallowtail (Papilio dardanus), Green-banded swallowtail (Papilio nireus).

Other similar species:

Citrus butterflies (Papilio anactus, Papilio eageus)

Green-striped Hawkmoth (Grapevines), Theretra jugurtha

Hawk or sphinx moths are very easy to spot with their streamlined bodes and large googly eyes. They are members of the Sphingidae family and the adults are active at dusk and feed on nectar. Larvae are hairless, bright green with a distinctive tail hook and pronounced eyespots. They pupate in the soil or under leaf litter in chrysalis.

Hawk moth caterpillars are fruit lovers, feeding either on fruiting bushes, vines or trees. They are often pests in orchard with damage to grapevines being severe. I also had huge infestations of these guys that came at my grapevine in waves! I only have one grapevine, so it goes to show how well the adults can sniff out grapevines on which to lay eggs. Be vigilant for these caterpillars if you have grapevines because they can destroy a plant within a few days before you even notice it (especially when you have had a lot of hail and you assume chewed leaves to be hail damaged leaves J).

Green  striped Hawkmoth large caterpillar on grape vine,
Theretra jugurtha

Green striped Hawkmoth large caterpillar,
mature ready to pupate,
Theretra jugurtha

Green  striped Hawkmoth,
Theretra jugurtha

Green  striped Hawkmoth,
Theretra jugurtha

Similar species in South Africa:

Cape Hawk/Grapevine Hawkmoth (Theretra capensis)

Other similar species:

Vine hawkmoth/silver-striped hawkmoth (Hippotion celerio)

Vine hawkmoth Hippotion celerio

Tomato semi-looper, Chrysodeixis acuta

Owlet moths from the Noctuidae (Agrotidae) family are highly destructive as adults and larvae. Night-flying adults pierce the skin of fruits which likely succumb to rot. Larvae are highly destructive, feeding on leaves and green fruits causing them to drop or rot or become hosts to other insects! Some species pupate in the soil (chrysalis) whilst others pupate in cocoons spun inside curled up leaves.

Spider has taken residence
in damaged tomato fruits

These are the biggest bane of my tomatoes, eaten leaves and green fruits. They caused about 30% loss in my tomato fruits last year (summer 2013) due to fruit drop or rot. I patrol the tomatoes in summer and check the underside of leaves and between developing fruits, pick of any culprits and feed them to the chickens (- at least I get my tomatoes back in the form of eggs J).

Silver U, Tomato semi-looper caterpillar,
Chrysodeixis acuta

Silver U, Tomato semi-looper pupae and moths,
Chrysodeixis acuta

Similar species in South Africa:

Golden Plusia (Trichopulsia orichalcea), Tomato/Cotton Leaf Moth (Spodoptera littoralis), African army worm (Spodoptera exempta)

Other similar species:

Green looper (Chrysodeixis eriosoma), Cabbage looper (Trichopulsia ni)

Cutworm (Any food crop seedling)

Cutworms are larvae from large groups of moths, Owlets (Noctuidae), who burrow in the soil and sever you seedlings at ground level. Morning reveals their night-time activity by a plot with ‘felled’ seedlings. They are very destructive and wasteful, cutting down an entire stand of seedlings overnight. There are several ways to stem their destruction through adding collars (cardboard) around your plants, starting your plants in pots and potting them out once they are large enough. Otherwise try potash, I think the tiny sharp particles aren’t fun to burrow through see more on my Pest control page. Starvation is another remedy, by leaving plot bare and removing weeds.

Cutworm, Noctuidae species
C-shape

Cutworm damage - a bit too late to put the collar on...

Cutworm collar

 Control

Birds are the main predator of caterpillars, seeing that most wild (black-eyed bulbuls, flycatchers) and domesticated birds (chickens) will do away at your vegetables as well – geese or ducks are more suited to insect pest control as their damage to food crops are minimal.

On the insect side, caterpillars are a favourite of parasitic wasps, but these are more suited to use in green houses (see Wasps post). Otherwise try to design your Insectary to attract paper wasps and mantids to clean out your caterpillar problems.

Biological caterpillar control

Chemical control likely would result in poisoning of other ‘higher’ insects, such as bees, spiders, mantids and wasps. Even organic solutions might affect other insects as well. Therefore, after biological control, I recommend removing them physically by hand and feeding them to the chickens (or put them out for the other birds J).

Preventative tips

The most successful way of limiting caterpillars is by reducing their host plant or making their host plant harder to find. Reduce large stands of one crop type (monocultures) and inter-plant your crops. This was very successful with my tomatoes, which I have had a reduction in crop loss by inter-planting the tomatoes and planting them far apart (limits walkover of caterpillars from one plant to the other).

Holes in tomato,
caterpillar damage by Tomato semi-looper

The best way to ID the caterpillar plaqueing your crops is to grab a few and 'incubate' them. Put them in a container with holes, feed them leaves and let it pupate. Photograph and take notes of the adult. The adult is the main ID stage for caterpillars. Most of the caterpillar here, I incubate in order to ID.

Green  striped Hawkmoth large caterpillar ,
infestation incubation,
Theretra jugurtha

Something cool: Earthwatch Institute

The Earthwatch Institute is a non-profit organisation that promotes research in the nature environment. They allow member of the public (volunteers) to join researchers on field expeditions when they collect samples and field data. You can join a research group by booking online at their website. Expeditions last several days to weeks and members of the public pay for their participation. Money raised through these expeditions is used for further research purposes.

Earthwatch

They have several projects, including ones for documenting caterpillars. They collect data on the biology and numbers of caterpillars in order to study their interaction with other insects, especially their parasitic wasps. The change in global weather pattern influence the rate of caterpillar developments, which in turn shortens the window for the parasitic wasps to locate, lay and develop in the caterpillar themselves. Researchers are interested in studying these dynamics, one such project, includes documenting the caterpillars of Costa Rica, more information on their website: EarthwatchInstitute.

"GRRR!"

Green  striped Hawkmoth large caterpillar on grape vine,
Theretra jugurtha

Related Posts/Pages

Pest Control

Wasps

Mantids

Insectary

Recommended Books for pest control: Natural Pest and Disease Control 

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Please share with fellow gardening enthusiasts via the various sharing buttons at the end of posts/pages! Else you can vote for posts through the Google reactions bar at the end of articles. To stay up to date I have provided several reader and social networking platforms with which to subscribe: Twitter, Pinterest, RSS Feed Reader or Email/Follow directly using the Blog Followers widget on the left hand side toolbar. Thank you for reading and please feel free to ask if questions arise - I appreciate comments and ideas too! 😆

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Food Revolution Summit: April 26 – May 4, 2014

Food Revolution Summit

Here is another online conference for those of you interested. Unfortunately I won't be able to listen to this one myself as I am going to be very busy during that time. It is a free online conference; you can register and find more information at their website: Foodrevolution.org

This summit is hosted by John and Ocean Robbins and concentrates mostly on food and the food economy (not specifically home vegetable gardening or food growing). It focuses on promoting health through healthy food choices.

P.S - I haven't forgotten about the summary post of the previous conference: Food Growing Summit 2014. I will be posting this in the near future! Watch this space!



Related Post:

Food Growing Summit 2014
How to start a productive and economic vegetable garden

Starting a Productive & Economical Food Garden (Part 1): vegetables worth growing

Squash harvest for 20 December 2013!

I wrote this post because when I started vegetable gardening I didn't think that it would save a lot of money (maybe come out square?). We started the vegetable garden as part of a ‘productive hobby’ and more for the food quality you get from growing your own vegetables.

The economic state of South Africa has changed a lot since then and food prices have sky-rocketed! Not only is food more expensive, but I look at what they want you to buy and eat in the market these days and I am utterly appalled! So, seeing that I am ensuring our food security and quality; I did a little research (and some number crunching) to see whether we are saving money by having a vegetable garden.

PnP peas with worms and mould!
I cannot tell you how many times I have found worms in store-bought peas,
this is why I split them before eating....
Peas are cool season crops, so at least I eat my own in winter!

I was blown away when I started to diligently weigh and catalogue our harvests – the garden was pumping out vegetables like a food factory! Then after I had a good few months worth of produce, I worked out what we save in terms of R/kg of produce…

I have an 80% savings!!! Money wise this means that form the summer (Sep-Mar) garden only, we have gotten R3500 worth of 1500 individual produce items, which amounts to 120kg of produce!!! I keep my input costs at a minimum, the rain tanks pretty much pay for themselves by harvesting rainwater - so no expense on water – and we produce our own super compost from kitchen/garden waste and chicken droppings – so no soil expenses either. Also we use dried grass clippings as mulch - so no mulch expenses as well. Therefore, my expenses are seeds, plants, fertiliser and the occasional tool, which means that we save R2800 (80% of R3500) for summer crops. We only buy produce these days that are ‘out of season’, such as winter crops of leafy veg, peas, cauliflower, broccoli and things we don’t grow such as corn or apples/pears (too hot for pome fruits here).

Note: The prices I mention above are for PnP prices, if you buy at WW we pay R 1000-1500 more for the 120kg of produce! I didn't weigh or add the prices of leafy things and herbs, so my savings are likely to be more than estimated above!!

Harvest of Sweet Potatoes: 23 July 2013

While I was looking up prices I saw that some vegetables are dirt cheap to buy whereas others are horridly expensive. I compiled a list of food crops which are expensive (and easy to grow) to cheap. This means that if you choose to grow food items that are expensive to buy you’ll have a more economically viable vegetable garden, so here is the list:

Food item	Rands per kilogram	Category
Herbs	333-500 (20/30g pack)	Very Expensive
Pomegranate	250-285	Very Expensive
Spice	200-400	Very Expensive
Nuts	160-280	Very Expensive
Asparagus	100-250	Very Expensive
Berries	120-200	Very Expensive
Figs	150-170	Very Expensive
Peas	150-170	Very Expensive
Ginger	100-150	Very Expensive
Baby spinach	100-130	Very Expensive
Spring Onions	100-120	Very Expensive
Button mushrooms	90-100	Very Expensive
Tender stem Broccoli	90-110	Very Expensive
Garlic	75-120	Very Expensive
Spinach	80-90	Expensive
Pineapple	70-80	Expensive
Lettuce	60-75	Expensive
Leeks	60-75	Expensive
Radish	65-70	Expensive
Cauliflower	50-60	Expensive
Cherry Tomatoes	50-55	Expensive
Limes	50-55	Expensive
Peppers	45-60	Marginally expensive
Patties	35-40	Marginally expensive
Grapes	30-50	Marginally expensive
Mango/Pawpaw	30-40	Marginally expensive
Large pumpkins	30-35	Marginally expensive
Beans	20-50	Marginally expensive
Standard Tomato	20-50	Marginally expensive
Avocado	20-40	Marginally expensive
Lemons	20-30	Marginally expensive
Citrus	20-25	Marginally expensive
Jewel Sweet Potato	20-25	Least expensive
Cucumbers	15-25	Least expensive
White Sweet Potato	15-20	Least expensive
Red Onions	15-20	Least expensive
Banana	15-20	Least expensive
Red Potatoes	13-15	Least expensive
White Onions	10-15	Least expensive
White Potatoes	10-13	Least expensive
Beet	8-10	Cheap
Carrot	6-10	Cheap

I must just add in here: I am absolutely shocked at the price of radishes - it is more expensive than cauliflower! I mean a radish is a fool-proof veg, you sow them in the ground, they pop up and three weeks later you have radishes! So, always have some of these in the garden!

So when you start out a food garden, an herb garden is a very good place to begin as they are:

ü    Easy to care for

ü    Use minimal water

ü    Very productive

ü    Save a lot of money

After herbs; getting stuck on growing leafy vegetables, fruits (especially figs and berries), peas!, asparagus, tender-stem broccoli, garlic, ginger, leeks, cherry tomatoes and peppers are good crops to follow the herb garden. After which, you can go onto the large pumpkins, scallops (patty pans), beans, lemons, standard tomatoes and grapes.

Harvest of lettuce: 11 July 2013

I am thinking of establishing an asparagus patch… also I would say that asparagus is better left for when you are a bit more experienced and they need 3 years to start producing! The rest in the above list are very easy to grow; stick them in the ground and watch them grow! Your tomatoes and peppers will do well with some pruning, whereas the figs and berries might need some additional care. Squash need a lot of space, but are very productive (especially the bush varieties), beans and lemons are easy to grow and prolific whereas a grapevine might be attempted by the more experienced gardener with advanced pruning skills.

Here are a few of the profiles I have done so far on the top-expensive vegetables & fruits:
Several herbs: Basil, Oregano, Rosemary, Sage, Thyme
Fruits: Raspberries, Tomatoes, Peppers, Squash & Pumpkin, Figs
Vegetables: Peas, winter leafy vegetables, Radishes

Harvest for 22 Feb 2014!

Some of the other ‘expensive’ plants are exotics, ‘baby’ or ‘red’ varieties of the standard ones (such as red potatoes or baby spinach). I would also recommend the growing of exotic fruit varieties to more experienced gardeners and sometimes it’s just not feasible to grow these as they are 10-20m trees (mangos, pawpaw, avocado) that love tropic conditions! (But nothing prohibits you from trying dwarf varieties or miniaturising them yourself, which does take a good deal of pruning & ‘bonsai-ing’ knowledge). Whereas others are not very prolific for the amount of space they take up, such as pineapples.

The other vegetables listed towards the ‘cheaper’ side are by no-means inferior – you simply cannot beat the taste, texture and satisfaction of home-grown potatoes, sweet potatoes, cucumbers and carrots! These are especially easy to grow as well!

The Boer Patty!
30 Dec 2013

With so many vegetables to choose from where do you start? You want to grow them all!

...I’d say that check your fridge and see what you eat, then make a list of potential candidates and weigh them against their costs in the store, space they take up vs. production and their overall maintenance. This is a good place to start your vegetable garden that will produce high-quality food and will be cost-effective as well!

Other articles in the Series

Part 2: Conservation Agriculture
Part 3: Integrated Organic Gardening
Part 4: Vegetable Garden Planting Guide & Management 


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Please share with fellow gardening enthusiasts via the various sharing buttons at the end of posts/pages! Else you can vote for posts through the Google reactions bar at the end of articles. To stay up to date I have provided several reader and social networking platforms with which to subscribe: Twitter, Pinterest, RSS Feed Reader or Email/Follow directly using the Blog Followers widget on the left hand side toolbar. Thank you for reading and please feel free to ask if questions arise - I appreciate comments and ideas too! 😆

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