Roots 'n' Shoots: March 2016

Sunday, 27 March 2016

Lacewings: Biological Control - Garden Critter of the Month

Lacewings at a glance

Occupation:
Predator
Value to Gardener:
5/5 - Pest Controller
Danger to Humans:
2/5 – Harmless
Availability:
5/5 – They’ll arrive or you can buy some


Lacewing Lifecycle: Chrysopa vulgaris
by Lydekker, R.
1879
The Royal Natural History.
Volume 6.
Frederick Warne and Co.
(from www.archive.org)


Quick Intro

Lacewings adults are delicate wee fairy-folk of the vegetable garden… but do not let them fool you as they are voracious hunters of pest insects and their larvae are known as ‘aphid lions’ with the looks to match!

Lacewing first instar larvae and egg cases on stalks

Science Stuff

Lacewings belong to the Neuroptera family of insects – they are not flies, in fact they are more closely related to beetles than flies (Ref 1). The order as a whole is very distinct in both their adult and larval appearance. Adults have elongated bodies reminiscent of dragonflies, but with transparent veined wings held in a dome above the body and iridescent eyes. Larvae have different body shapes and are similar in appearance to ladybug larvae but have very large mandibles. Several families are found within the order, but most of the pest controllers are located within the Chrysopidae family.

Habitat

As with many other pest predators; they will be attracted to areas with lots of prey species. Those most commonly found in gardens are the most widespread throughout South Africa. They are attracted to lights and thus you might find them inside the house – scoop them up and release back to the garden!

The 3 common species to look out for are:

1. Green lacewing: Chrysoperla species are green with a ~3 cm body and their wings have no markings. Found throughout South Africa.

Green lacewing,
Chrysoperla species

2. Yellow lacewing: Ceratochrysa antica are yellow and slightly larger than the green lacewing. Wings also have no markings. Likely to be found in Gauteng, KwaZulu-Natal, Mpumalanga, Limpopo and the eastern parts of the North West province.

Yellow Lacewing,
 Ceratochrysa antica


3. Grey lacewing: Chrysemosa jeanneli are smaller than the green lacewings with grey bodies and grey wings. They have a distinctive black spot on the mid hind margin of their wings, which meet up when their wings are at rest. Found throughout South Africa.

Grey lacewing,
 Chrysemosa jeanneli 

The best way to attract predators is to limit synthetic pesticide use in the garden and to opt for environmentally friendly versions, which will not harm them (See my Pest Control Page). Unfortunately, pest populations have to become gargantuan in order to attract pest predators, but once they arrive they will sort out the infestation in double-quick time! For the adults who may feed on pollen/nectar – be sure to have plenty of small bloom plants as these are more suited to these insect’s size to get ahold of the contents. Lacewings have a preferential liking of Asteraceae flowers (sunflower, cosmos, dandelion) that make several tiny flowers in large clusters, as well as flowers from the Apiaceae family (dill, fennel and angelica).

Diet

In the family Chrysopidae, adults and larvae are mostly predatory and will feed on aphids and other soft-bodies homopterans (mites, scale, leafhoppers and mealy bugs). Adults from the grey lacewings are suspected to be pollen and nectar feeding (and hence might help out with pollination when feeding). Lacewing larvae are known as ‘aphid lions’ or ‘aphid wolves’ as they are able to devour up to 100 aphids a week! Grey lacewing larvae also display a type of camouflage behaviour by carrying devoured prey carcasses on their backs! [See Picture Here].

Green lacewing adult eating aphids

Green lacewing larvae eating microscopic scale 


Lacewings: Mantidflies and Antlions

The order of Neuroptera have additional members outside of the agricultural pest control familes with some of the most interesting morphologies and lifecycles. These include the Mantidflies or mantispids (Mantispidae), which resemble miniature mantid-wasps! Adults use their raptorial forelimbs to grasp prey just like mantids. Mantidfly larvae feed on young spiders or spider eggs and pupate inside the egg sacs. 

Mantidfly wasp mimic,
 Pseudoclimaciella species 

Antlions are the largest family of lacewings, best known for their whirl sand burrows wherein they catch unsuspecting ants. The larvae sit at the bottom of the funnel pit and when an ant happens to fall in it is unlikely to escape before the antlion snatches it up with its mandibles - although some jumping behaviour has been observed by would-be victims with various results. Antlion adults are large, lazy fliers. Some have spotted wings and/or resemble damselflies. 

Spotted winged Antlion,
Dendroleon obsoletus
Ant traps - there be lions!


For some websites where you can purchase lacewing eggs (Note these are likely not going to ship outside of the US!): Planet Natural & Arbico Organics

[Unfortunately such companies are not available in South Africa - we have to resort to the old fashioned way = by nature!]

Ref 1: Neuroptera Phylogeny

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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: TwitterPinterestRSS 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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Saturday, 12 March 2016

Lessons from Gardening in a Drought



As the world goes round and progresses through each of its cycles El Nino has claimed its turn with a triumphant roar this year! The Northern Hemisphere has reported record crop yields, lots of rain and bountiful snow. The Southern Hemisphere (specifically Africa) has reported widespread crop devastation and several areas had declared natural disaster zones! Here I will be posting the seasons’ fight against the worst drought to hit South Africa since records started in 1904 (second lowest annual rainfall was 1945, but the longest dry period was 1930-1933, see Ref 1), the observations I made, the final throw in of the proverbial towel and the plans for the coming winter.

My vegetable garden has already experienced below average rainfall for the 2014/15 summer season and the 2015/16 round was looking dire. Early rain in September (51 mm, 42 mm more than last year) gave me hope, but almost no rain in October and November (46 mm for both months, ~30% of the rain than last year) had nearly wiped out our 15 000 L of stored rainwater. The high heat, solar radiation and measly rain had left the vegetable garden battle fatigued – not to mention the household as well since we couldn’t seem to gather enough grey water from the house to keep everything in the yard alive and we worked like slaves to save the plants (and wild animals, by means of the chicken waters being drained every day).

A quick table of our rainfall for this summer season (and a comparison to last year's):

Rainfall
2014/15
2015/16
Aug
5
10
Sep
9
51
Oct
29.5
11.5
Nov
111.3
34.5
Dec
125.5
124.5
Jan
126.5
143.7


Much needed rainfall in December and January refilled the tanks, much to my relief as well because I was starting ‘prioritise’ plants for watering – some losses were inevitable. The garden did not do well mostly due to the fact that it only received enough water to stay alive let alone provide a decent crop. Some vegetables did fair better than others, so here is a quick list for drought “viable” crops:

Tomatoes – did especially well in the vegetable cage, we had an overflow
Beets & Carrots – did not seem to mind the heat and set root very well
Peppers – seeing that the fruit is mostly hollow, little water is used and fruiting isn’t impeded by the heat
Peanuts – my ongoing experiment with peanuts actually thrived in the heat!

What about potatoes and sweet potatoes? Not so much, small tuber formation given the litres of water I chucked on them. Pumpkins & Zucchini – nope, very few and tiny fruits. Given the drought I was hopeful for at least 50% of last year’s harvest but then on the 9th of January a freak hailstorm hit Roodepoort and wiped out our harvest – even breaking the vegetable cage (luckily no plants were damaged!)! Our tiny pumpkin harvest, any tomatoes, peppers and other soft fruit that were not completely covered by shade netting got decimated. Those fruits with only a little damaged quickly succumbed to rot in the heat of the following days.


The chicken coop got hailed shut and one of the chickens was being broody in the veld. So we were convinced that she perished in the veld during the hailstorm. Luckily I was at the window when she arrived just after the worst of the hail. I rushed out to grab her but couldn't get the coop open so she went back into the house with me. I dried her off and she stayed in one of the cat boxes overnight. Fortunately she made it through the night and had no injuries - though she was straight out of her broodiness afterwards!

So it is safe to say that after the hailstorm I just basically declared defeat against the elements! I didn’t even want to look at the garden lest alone repair the damage. I think I abandoned it for about a month (fortunately it rained enough during this time and additional losses were avoided)… Presently I have revitalised and resuscitated most of the garden and have made some plans for the winter.

Initially I did not want to plant any vegetables for the winter as last year’s winter garden was a disaster because it was merely too warm for the winter vegetables to crop properly. I have been hearing rumours of a cold winter this year and the outrageous food prices have given me new motivation to plant everything under winter veg!

I am planning the bulk of the winter vegetable garden in the vegetable cage – it is a lot colder there in the winter than the main garden since it is situated in a dip of the yard. The vegetable cage will housing the bulk of the vegetables, such that I’ll plant all the cabbages we eat (tender stem broccoli, cauliflower, pak choy and leaf cabbages), leafy greens (lettuce & baby dash spinach) and lots of peas! The main garden I have reserved for soil building and leafy vegetables that can cope better with more warmth, such as wild clover (to be turned into the soil at seasons end), bush beans, Swiss chard (lots of Swiss chard so that the chickens can have their beloved greenies in winter too) and tons of onions (spring, shallot and leeks!).

Main lesson from gardening in a drought? Well you better plant a whole lotta flippin’ tomatoes!




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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: TwitterPinterestRSS 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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