While the lacewings, when they aren't irrelevant to agriculture, are entirely beneficial, the bugs are... more uneven.
Listen very carefully - I will say this only once.
(That's not true, but I couldn't resist a little 'Allo 'Allo! reference)
 |
Erachteus lutulentus in streamside vegetation in
Mafinga Hills, Muchinga Province, Zambia |
Resistance is what it says on the tin: how well
or how poorly a species resists any attempt to
control it. If we're going to be trying to slaughter
a living population en-masse, we should probably
try to get a little bit of empathy going for them,
so we'll use an analogy of humans, not stink-bugs,
but because I can see that people would think it
more than a little flippant if I, um, flipped the
popular analogy of comparing genocide to pest
control, we'll try to present them as victims of a
 |
Glypsus, a predatory shieldbug, in cropland in
Chisamba, Central Province, Zambia |
war-of-the-worlds situation rather
than a Zimbabwe*** / Tasmania / U.S.A. / New Zealand /
Australia / U.S.A. / Russia / Argentina / South Africa*** /
Brazil / Namibia / Turkey / Turkey / Turkey / Russia / Russia /
Libya / Kazakhstan / Ukraine / Poland / Latvia / Poland /
Germany / Croatia / Croatia / Poland / Russia / Guatemala /
Bangladesh / Burundi / Cambodia / Timor-Leste / Bangladesh /
Iraq / Zimbabwe*** / Somalia / Bosnia and Herzegovina /
Burundi / Rwanda / D.R.C. / Sudan / Iraq / Myanmar et al**** situation.
In this analogy, our heroes, Jack and Jill, are up a
hill when an Alien Spaceship arrives. Jill climbs
a rope down the well, while Jack stares in
astonishment at the pretty lights. When the aliens
drop a firebomb, Jack is incinerated, while Jill,
halfway down the well, gets away with mild burns.
Jill is showing behavioural resistance. When
the fires die down and she climbs back up, she
will presumably find some other quick-thinkers,
 |
Sciocoris in garden
in Chongwe, Lusaka Province, Zambia |
eventually have children, and teach her children
the importance of hiding from aliens with firebombs,
so that they will also (at least mostly) show
behavioural resistance.
Forty years later, let's say the aliens come back and,
when their firebombing proves ineffective, spray
all inhabited areas with aerosolized peanut butter.
Anyone allergic (Epi-pens were all burnt in the
firebombing, sorry) is toast, but the rest of the
population is probably just perplexed, and show
chemical resistance: they are physically immune to
 |
Sepontia misella in orchard in Chongwe,
Luzaka, Zambia |
this particular attack; and although allergies are far
from perfectly hereditary, if the aliens try again a
generation later, they will probably find that it is even less effective.
In this example, our misguided alien would-be overlords
are attacking the entire planet, Independence Day style,
so each new generation of Jill's descendants is descended
exclusively from survivors of a previous invasion.
Now imagine that the aliens are only interested in, say,
Kentucky, which just happens to be where Jack and Jill
start out.
 |
Veterna sanguineirostris in garden
in Chongwe, Lusaka Province, Zambia' |
Now, when Jill emerges from her well, she might join
with other survivors of the state-wide firebombing, or
she might walk through the burnt husk of her state and
into Tennessee, where she meets and falls in love with
Bob. Bob lives in a boring little flat in the city, and
when the Aliens don't seem to be coming back, Jill and
Bob move to Jill's farm and set up shop. Jill tries to
instill the importance of hiding from spaceships in her
children's minds, but Bob isn't entirely certain that it
really happened, so when the pretty lights appear in the
 |
Stenozygum in cropland
in Kafue Town, Lusaka Province, Zambia |
sky again, only a few of the now adult children remember
Jill's advice and scramble down the wells, and, like Jill,
any survivors might choose to marry people who come
from outside state lines, even if they re-settle Kentucky
in the end (if you think that people wouldn't be so
foolish as to live in a place where aliens invade every
forty years, bear in mind that plenty of humans around
the world live on flood-plains and in hurricane zones
and on active volcanoes). The result is that, although the population of Kentucky is regularly under selection
pressure for resistance, the genes coding chemical and
behavioural resistance are rather unlikely to get fixed,
because there are more potential husbands and wives
from out-of-state than in-state, and so there is a constant
in-flow of naïve genetics into Jill's family tree.
In case this seems irrelevant, read "Kentucky"
as your field. The point here is to demonstrate that
the rate at which a pest population develops resistance
 |
Eurydema ornata in roadside ditch near
Hündeleskopf, Bavaria, Germany |
is slower in populations that are not all placed under
the same pressure. Jill Mk I, living in a world reduced
to peanut-buttery ash by aliens, is a stink-bug living
in the middle of an intense, no-acre-spared, commercial
farming block. Jill Mk II is instead living on a field
surrounded by woodland. From the farmer's perspective,
Jill Mk II and her descendants are much easier to control,
while Jill Mk I's grandchildren will eventually reach such
numbers that the 40-year aliens give up on farming earth
entirely, and try to set up their weird blood-weed farm on
Mars instead.
So now that we're through with that slightly disturbing
little analogy, you hopefully have a nice little checklist
to go through next time you think about spraying, and
we can move on to:
 |
| Lerida punctata in cliffside vegetation in the Kundabwika Heritage Area, Northern Province, Zambia |
 |
Macrorhaphis acuta, a predatory stinkbug in garden in
Chongwe, Lusaka Province, Zambia |
Benefits (No, Really, We're STILL doing the
farming thing)
I thought about doing another problem, vis-a-vis their capacity to spray a liquid with
the approximate smell of rotten coriander at potential threats, but after we've put
ourselves into the shoes of the War-of-the-Worlds alien trying to wipe out Jill and her
descendants, that seems a little bit too trivial to mention in full size font.
Caterpillar Control: It's worth noting at this point
that this is usually
different species to the stinkbugs
that can become a pest when you spray to control
caterpillars, but in addition to genera such as
Dalsira and
Basicryptus, the entirety of the
subfamily Asopinae is composed of predators
of caterpillars(and other soft-bodied prey).
They're not usually
as
 |
Menida dubia in riverine thicket in
Mutinondo Wilderness Area, Zambia |
voracious as some predators, such as Lynx spiders
(Aranae: Oxyopidae), but they're also a lot better at
not eating each other than most spiders, so they can
sometimes reach high densities in the environment.
Predator/Parasite Reservoir: This is one of those
benefits that seems like a cop-out, but is much more
important than most people realise and/or
ackno
wledge. If you're managing your farm in a
population-dynamics conscious manner, and doing
everything that you can do to ensure that your farm
does as little as possible to disrupt local ecology, you
 |
Green Shieldbug, Palomena prasina, in Bosham,
West Sussex, England |
will still have (hopefully rare) pest outbreaks. This
would even be true if you were farming on, say, a
desert island or some sort of experimental Russian
agricultural space-farm: whether it's your neighbour's
overindulgence on carbamates creating an outbreak of
fall armyworm, El Niño on climate-change steroids
creating a series of drought years leading to an explosion
in locust populations in the western grasslands, or just
a weird smear on Svetlana's boot that ends up turning
your thriving space-tomatoes into a soggy pile of
космический компост.
 |
Parantestia cincticollis (red morph) in garden
in Chongwe, Lusaka Province, Zambia |
In all of these situations, how much of a crop you can
recover depends in no small way on the speed with
which you can begin to defend your crop. In your very
best case scenario, you would start responding before
you noticed the problem.
No, you don't need time-travel to do this.
What you need is a healthy population of natural
predators and parasites.
Seeing as we realised at some point
after we wiped out
the dodo that God doesn't just 'pop' animals into
existence whenever we might have need of them, I'm
sure that we can all agree that your predators and
parasites are going to need to have a good reason to be
 |
Red-Legged Shield-Bug, Pentatoma rufipes on roadside
in Fishbourne, West Sussex, England |
in any given area - which means that they need to eat.
Now, obviously, the beneficials that you most want to
attract are the ones that are most likely to eat (inside
or out) your most important pests, but despite the benefits of retaining a control-
naive population, it's a rare farmer who can
be convinced to maintain a healthy population
of his bitterest enemies just to ensure that
their
bitterest enemies are well fed.
The next best
thing is to maintain the closest
non-pest
relatives to your pests, as close as possible
to your fields - while some parasitoids
are very
specific, most have a narrow range of hosts - such as a
pest species and seven or eight related, non-pest species.
 |
Spiny Shieldbug, Picromerus bidens (predatory) in
downland meadow in Kingley Vale, West Sussex, England. |
This is not going to be the last time that I say this, but this is why
uncultivated
margins matter. These provide a crucial
environment for hundreds of species
that have
no interest whatsoever in your
crop (and yes, a handful of species that
do
have an interest in your crop), which in
turn can support
dozens of species that
directly benefit your crop, primarily
through predation and pollination.
For reasons that are hopefully obvious, these
beneficial animals are more valuable if there are
more of them. I'm not saying going out and buy
 |
Piezodorus purus in garden
in Chongwe, Lusaka Province, Zambia |
a bunch of ladybirds (please don't - the consequences
can be disastrous if it's the wrong ladybird), I'm
saying that you want to start thinking about
thickets.
Thickets - the dense, often impenetrable habitat that
forms as a transition between open, grassy habitats
and canopied forest or woodland - are an incredibly
rich environment that can support a fantastic diversity
of invertebrates and other small animals, and of
all
the natural habitats you should seek to provide on
your farm, thickets are the ones that will serve you best.
 |
Pseudatelus natalensis, in grassland
in Chongwe, Lusaka Province, Zambia |
But what's this I hear you say? My thickets are all gone,
or too far from my crop to provide a convenient living
arrangement for beneficial predators and pollinators?
Three words.
Plant.
A.
 |
Bronze Shieldbug, Troilus luridus, in woodland
at Kingley Vale, West Sussex, England |
Hedge.
By which, I must be clear, I do not mean a topiary
boundary. I mean a hedge. It doesn't have to be native
species; it can be fruit bushes or ornamental species
(unless they are
allelopaths, like
Lantana camara,
which stunt and kill the plants around them - try to
avoid those) - and then
don't discourage the assortment
of native vines and trees that do move in, just trim them
back every year or two, to keep any of the component
species from excluding the rest.
 |
Tyoma cryptorhyncha in grassland
in Chongwe, Lusaka Province, Zambia. |
It has been said before, and I will certainly say it again,
but
Hedges are wonderful. They are a DIY thicket,
give a huge boost to a vast range of wildlife species,
and they allow you to bound your entire
crop with humming apartment blocks for
your beneficials - for instant access and
rapid-response control. They also help to
reduce erosion and moisture loss in the
immediate area, and a diverse mix of
different trees and shrubs creates a nutrient-
rich mulch, which boosts fertility in adjacent
crops. In the dense agricultural landscape of
Britain's 1600s to 1800s, they were a staple of
actually keeping the land productive, and they
are one of the (fairly few) aspects of European
agriculture that are readily transferable to
other climates and soil types; arguably, because our insect populations don't have
the same annual reset as is found in much
of Europe, they are
more effective in
countries like Zambia than they are in
cold-temperate regions.
For farmers who rely primarily on large machinery and automation, installation of hedgerows is limited to the margins of large fields, which
does limit their capacity to control pests. For smaller farmers, the fertility boost that the surrounding crop receives more than compensates for the cropping area lost by breaking up larger fields with a hedge or twenty. Treat 6 metres as its maximum height - and, bearing in mind that lower hedges have a reduced "reach" in terms of limiting erosion, wind damage and water loss, you can go as low as 1m and still give a massive boost to your beneficial insects.
Plant hedges. For you, for your crop, for the insects, the climate and all our futures. They are excellent.
Anyway, where was I?
Oh, yes. Stink bugs.
So, we've done the big one; the rest will be quick.
One half of the above statement is true. It's the first bit.
 |
| Platacantha lutea in riverine vegetation on the lower Zambezi, Lusaka Province, Zambia. |
Shield-Backed Bugs of family Scutelleridae
 |
| Rainbow Shieldbug, Calidea dregii, in scrub in Chongwe, Lusaka Province, Zambia |
 |
Hotea subfasciata in garden
in Chongwe, Lusaka Province., Zambia |
Let's get it over with: These are
not ladybirds, or
ladybugs or ladybeetles (and all those things are
beetles, anyhow).
If in doubt, look closer: ladybirds - like most beetles -
have a distinct seam where their hardened forewings
meet; in Scutellerids, their wings are entirely or
almost covered by their massively expanded
scutellum, so no seam. The ladybirds - as beetles -
also have fairly standard mandibles, while
Scutellerids, as bugs, have a bug-standard rostrum -
essentially a drinking straw - which is tucked neatly
 |
Sphaerocoris testudogrisea in scrub
in Chongwe, Lusaka Province, Zambia |
under their bodies when not in use.
So where do they figure in agriculture?
Well:
Problems: Less than above. Well, less species, at least.
While the overwhelming majority are completely
uninterested in your crop, a couple of species can be
more problematic - and at the top of that list are the
very pretty "rainbow shield bugs",
Calidea.
Calidea, particularly the common
Calidea dregii, are
 |
Picasso Bug, Sphaerocoris annulus in woodland
in Kundabwika Heritage Area, Northern Province, Zambia |
rather polyphagous - a trait that is shared with
Nezara viridula, the most important African pest out of all the many species of
Pentatomoidea. They and other
Scutellerids are generally considered
lesser pests for two main reasons: First,
their generation times can often be longer***** and produce smaller
generations, so
populations expand
rather than explode, and their hosts
do
not include Zambia's most
economically important row crops.
That is not to say that do not affect important crops -
cotton, sunflowers,
cassava,
sorghum, cashew nuts,
Jatropha and
Macadamias are just a
handful of the crops that they can and do
feed on, and while most farmers these days
have entirely lost interest in
Jatropha as a
crop, many of this species' hosts are
important either as local staples or as
smaller-scale commercial ventures.
A common feature of most Hemipteran crop pests -
 |
Steganocerus multipunctatus in orchard
in Chongwe, Lusaka Province, Zambia |
whether we're talking Aphids or Shield bugs - is that
they tend to be secondary pests. Because the crops that
Calidea feeds on tend not to be subjected to such heavy
pesticide regimes, they also do not
tend to suffer such
heavy infestations of secondary pests, and
chemical control is not usually viable.
But perhaps the most important factor limiting the
importance of this species as a crop pest is that
Adults
and nymphs cannibalize eggs.
As monstrous as this might seem, it makes pretty good evolutionary sense: All life-stages in this species feed
 |
Solenosthedium liligera on dung in woodland
in Mutinondo Wilderness, Muchinga Province, Zambia |
in the same way on the same host plants, so young and
adults inevitably compete. When there are abundant
adults around, newly hatched nymphs will reduce fitness of adults through competition, and most likely die - wasting resources. Opportunistic cannibalism of eggs ensures that this competition does not happen as often, and that hatching only occurs following a die-off of adults, such as after a period of heavy storms (or pesticide application), and so the nymphs are not competing with their parents for the same resources.
Benefits:
Beyond
Calidea's cannibalistic self-regulation, direct benefits to the crop are few - but, as with everything else, the non-pest species add valuable diversity and resulting stability to ecosystems, helping to ensure that your directly beneficial species are there when you need them.
An effect - and you can decide for yourselves whether it is beneficial or not - is that by feeding on the young stems of woody plants, they can often weaken or kill the growing point - which helps to stimulate branching. Many sap-sucking bugs have this type of effect on plants, and few wild plants seem to be particularly harmed by this.
Pill Bugs of family Plataspididae (or Brachyplatidae)
 |
| Coptosoma affinis in riverine woodland in Chief Nyalugwe's area, Eastern Province, Zambia |
 |
Coptosoma conspersa in riverine woodland
in Kabwelume-Lumangwe Heritage Area,
Northern Province, Zambia |
When it comes to the pill-bugs, there really isn't much to say other than "they're quite neat-looking". They can be fairly common - but I've never encountered them at anywhere near plague proportions, and they generally don't show much interest in crop species.
In terms of life history they are much like the
 |
Coptosoma nubilum in grassland
in Chongwe, Lusaka Province, Zambia |
Scutelleridae, but - at least regionally - they tend to
be smaller, rather short-bodied and rather less showy.
If the phylogeny of
Lis et al. (2017) is correct, they
may have a more interesting backstory than I usually
give them credit for - they are descended from within
the paraphyletic assemblage that we all (?) know as
the Cydnidae, inviting speculation (mine) that they
were more like modern Cydnids in their past, and
have arrived at a similar form and lifestyle to the
Scutellerids by an independent route, rather than
simply being an early offshoot from the Scutelleridae.
Burrowing Bugs of family Cydnidae
Parastrachiidae are here considered not to be a real family but a scattering of near-Sehirine Cydnids - hence inclusion of Dismegistus images. Seefor justification. By the phylogeny presented in the same paper, the Plataspididae should proably be sunk into this family, too.
While we are in the
mostly-agriculturally-irrelevant section of the superfamily at this point, the Cydnidae are probably the least irrelevant of
these. The vast majority of them have no interest in any crops, but they can still have....
Problems:
Direct Feeding on Crop Roots.
 |
Dismegistus cf fimbriatus in riverine vegetation,
Mutinondo Wilderness, Muchinga Province, Zambia |
This is mostly a New World problem, but to avoid seeming like I support nationalist philosophies, I'll briefly mention them here: least controversially,
Cyrtomenus bergi feeds on the roots of cassava. The main problem this causes is aesthetic: most of the time, the damage is limited to a fairly shallow brownish spot on the cassava, without reducing yield or edibility, but these puncture wounds
can open the plant up to infection
by various pathogens - although that is rare.
The more controversial "pests" are the various species of
Scaptocoris, which can feed on the roots of various different crops - but more on them under benefits.
Incidental damage
In most of the world, if you have a problem with Burrowing
Bugs, this is it: they move around in the soil. Plants roots are
in the soil. They do not necessarily show all the due care and
attention when moving past your plants roots that you might
 |
Lalervis tibialis in garden
in Chongwe, Lusaka, Zambia |
like, and sometimes their movements cause physical damage.
In most settings, this does not actually cause any real harm: plants have actually spent less time on land than small burrowing animals, and as such are quite used to occasionally having to regrow a bit of root. However, soils under heavy agriculture tend to be both more waterlogged and more compacted than the soils that the crops wild ancestors would have preferred, with the result that both burrowing insects and plants' roots are concentrated in a greatly reduced area of habitable, aerobic topsoil - so
damage is higher than it might be in a natural system.
Unless your soil is
very compacted and your
Burrowing Bug numbers
very high (unlikely - see
below), most crops absorb this damage without
any apparent drop in yield.
So now we have to talk about:
Benefits:
Soil Aeration:
Agricultural soils tend to compact over time; even in zero-til situations - rain falling on bare soil leads to a fair amount of compaction, even
without heavy machinery.
Fortunately, the world in general - and African soils in particular - are used to a fairly good analogue of heavy machinery: large vertebrates have been trampling over land surfaces, especially in fertile plains that lend themselves to agriculture, for somewhere in the region of 300 million years. The periodic dips in abundance probably aren't the reason that Africa's ancient soils haven't compacted into rock by now. Instead, the saviours of agriculture come in the form of animals that (mostly) inhabit the opposite end of the scale: worms, beetles, grubs and burrowing bugs create openings in soil as they go about their daily lives, allowing air and water into places it couldn't usually go, and creating a dynamic environment for the roots, plant stems and fungal communities that should be the backbone of any long-term fertile soil.
This beneficial effect isn't limited to invertebrates: I plant agapanthus and cordylines in the full expectation that most of them will be eaten from the bottom up by Ansell's mole-rats, an endemic eusocial mammal whose ceaseless burrowing is an easy improvement for drainage and decreases erosion through run-off - but in most crops, larger animals are going to cause considerable headaches, and mole-rats in particular aren't going to be in your crop if they can't eat it, and they can eat a
lot. So burrowing bugs are a lot more convenient.
 |
Pied Shield Bug, Tritomegas bicolor, in cropland
in Bosham, West Sussex, England. |
Crop Protection:
So this section
may be irrelevant to African species, as to my knowledge it has only been demonstrated for the
American
Scaptocoris - but it may be considerably less than irrelevant: as with most members of the Pentatomorpha, the Cydnidae
possess
stink glands (Hence "Stink Bugs"...) and out of these small and inconspicuous chemical factories, some
Scaptocoris are known to produce natural 'cides - which in
the case of Scaptocoris talpa at
sufficient densities, can protect tomato seedlings and
bananas from pathogenic fungi and nematodes - although
the densities used in the study were to my mind rather
high, bananas in particular are incredibly prone to fungal
infections, so anything that could reduce the need for expensive
chemical protection is worth looking into.
Inflated Shield Bugs of family Tessarotomidae
 |
| Natalicola pallida in Garden in Chongwe, Lusaka Province, Zambia |
Although this is very firmly a small family, they are - at least regionally - far from irrelevant. Over Zambia they tend not to reach particularly high densities, presumably because our woodlands don't favour their favourite host plants, but in various communities in South Africa, the edibility and seasonal abundance of these little guys makes them a valuable foodstuff. There's more about that in my post dedicated to still-the-only-one-I've-met-in-Zambia,
Natalicola pallida (Westwood, 1837)
Agriculturally, though, they pretty much irrelevant except for enhancing diversity and thereby stability of the hedgerows and marginal woodland that you have surely decided to plant if you've reached this far down in a post that is already leviathan (and I'm saying that
before I've even added pictures).
Watermelon Shield Bugs of family Dinidoridae
 |
Coridius in woodland in Kabwelume-Lumangwe Heritage Area,
Northern Province, Zambia |
Whoever said that the small families are of no economic importance?
Problems:Eating Your Cucurbits
If you live in Africa, and are growing crops of the family
Cucurbitaceae - the family of cucumbers, watermelons, squashes and gourds - you have probably met this family. They are not
all pests (of course) but several species of
Coridius, probably the most successful genus regionally, do have an unfortunate habit of feeding on watermelons and pumpkins, which any drive along Zambia's major roads will show you are very important crops locally, and
Coridius also feed on various other regionally popular vegetables.
Although they tend to fall victim to a similar range of predators and natural controls as species such as
Nezara, populations of specialist pests are rather easier to manage through planting habits: by limiting the continuous area of suitable host plants - i.e. separating small fields of crops by hedges or set-aside, and using mixed-planting and intercropping to their full potential - you can keep most specialist pests from ever reaching numbers where control is necessary or makes any economic sense.
The Other Shield Bugs of family Acanthosomatidae
The Acanthosomatidae are usually treated as rather basal within the Pentatomoidea. Like the Plataspididae, they are offered a move to new and exotic locations by Lis et al, 2017, who indicate that they are rather closely related to the Cydnidae - more closely related, in fact, than some of the other Cydnidae. This is not nearly so well supported by Lis et al's data as the nesting of the Parastrachiidae into a subfamily of the Cydnidae, and the higher-level taxonomy of the superfamily is rather weakly resolved by their study, so - as with the Plataspididae - I am continuing to treat them as separate family.
A single species
probably enters Zambia, the widespread
Uhlunga typica, which turns up all over sub-saharan Africa, but I've not yet met it. You're probably
not going to find them in your crops - any crops, but if you do, they are almost certainly there by accident.
In case you can't guess from the "probably", I have not yet met Uhlunga, and can't show you a picture.
Sorry.
Here's a European one instead.
And - well, it seems like that's all, folks?
