BUSHBUCK HILLS NEWSLETTER April 2020 The name ‘green drab’ really doesn’t seem fitting for this moth. Green yes but by no means drab. They are frequently attracted to lights during the evening but seemingly even more so by the mud and presumably minerals round the dams. The one above is looking particularly fresh and clean possibly having just emerged. The caterpillars of many moth species dig into soil prior to becoming a chrysalis so have to emerge from the soil when they have pupated into their adult, moth form. Many moths seem to be attracted to the dam margins during the evenings, whilst butterflies seem to be equally attracted during the daylight hours. Cut-throats on the farm. Not to worry though, these ones are ‘Cut-throat’ finches. They are named after the red band that stretches under their chins and around to their cheeks. Apparently they frequently associate with their slightly more common red-headed cousins but in this case it was a single bird sitting in the Senagalia caffra in front of Huis-karee. It did however join a mixed party of yellow-throated petronias and southern grey-headed sparrows to feed on some seed that had been scattered on the ground. Green drab (Ophiusa tirhaca) Cut-throat finch
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BUSHBUCK HILLS NEWSLETTER April 2020
The name ‘green drab’ really doesn’t seem fitting for this moth. Green yes but by no means drab. They are frequently attracted to lights during the evening but seemingly even more so by the mud and presumably minerals round the dams. The one above is looking particularly fresh and clean possibly having just emerged. The caterpillars of many moth species dig into soil prior to becoming a chrysalis so have to emerge from the soil when they have pupated into their adult, moth form. Many moths seem to be attracted to the dam margins during the evenings, whilst butterflies seem to be equally attracted during the daylight hours.
Cut-throats on the farm.Not to worry though, these ones are ‘Cut-throat’ finches. They are named after the red band that stretches under their chins and around to their cheeks. Apparently they frequently associate with their slightly more common red-headed cousins but in this case it was a single bird sitting in the Senagalia caffra in front of Huis-karee. It did however join a mixed party of yellow-throated petronias and southern grey-headed sparrows to feed on some seed that had been scattered on the ground.
Green drab (Ophiusa tirhaca)
Cut-throat finch
VulturesUnfortunately we have had a second male giraffe die by the southern border of the top field. It’s not certain whether this was an interaction with a bull on the other side of the fence, or whether our bullwas trying to cross the fence line to get to the cows on the other side. The carcass of the first giraffe
was sold to a butcher but circumstances were against that happening this time around. As such the carcass was moved to the vulture restaurant closer to the middle of the field.Later in the week a large number of vultures were seen next to, and on top of the carcass. At that point only the neck had been eaten leaving the body pretty much intact. There were about one hundred or possibly slightly more birds in attendance. When disturbed they flew into the nearby trees – all along the edge of the field and some even perched in trees further down the top ofthe stream road. A trail camera was added to the steel pole adjacent to the restaurant to see what images could be obtained. All of the vultures initially seen were white-backed vultures – the
same species as have been previously seen on thefarm. They all looked in tip-top condition andvery well fed. Possibly they had already beeneating off the carcass for a couple of days.Despite eating dead animals these vultures canhave trouble gaining entrance to the carcass.Because of this they sometimes have to wait for avulture with a sharper or larger beak, such as thelappet vulture to help cut through the skin, oranother scavenger such as brown hyaena to breakopen the body of the carcass. For some reason our
Immature white-backed vulture alighting on carcass White-backed vulture feeding from the opened carcass
White-backed vulture after eating.
A small group resting
own resident brown hyaenas didn’t seem to be making an appearance and so human intervention was made to cut open the belly and haunches, part of which can be seen in the photograph above.
As a seeming late-comer, a Cape vulture turned up - on the right side of both the photos above and below. Identification pointers for the cape vulture are, the predominantly naked and blueish neck and head, the pale not dark eye, the blueish patches of naked skin either side of its chest and finally the brown spots on the under-wings adjacent to the flight feathers. The cape vulture is a much largerand heavier bird than the white-backed vulture. It’s wing span is approximately 2.6 metres versus 2.2 and weighs in at an average of 8.5 kg versus ‘just’ 5.5 for the white-backed vulture. Both species can consume meat very quickly – a necessity when there is a lot of competition around
them. Figures given are for a kilo of meat in 2 to 5 minutes per bird. After eating this amount of meat they can go for three days without another meal. During this time they will usually bathe, preen, sunbathe and rest. Vultures spend quite a bit of time sunbathing even if they haven’t bathed. This is thought to aid the process of getting rid of feather parasites. The parasites not enjoying beingover heated move away from the heat and inadvertently move to where the bird can remove them with its beak – the birds will often spend some time preening directly after sunbathing.
Cape vulture showing the naked patches of blue skin (to the right)
White-backed and Cape vultures
In the photo above the reason for the White-backed vulture’s name becomes apparent. This patch ontheir back is only seen when the birds have their wings spread in the sun or when they are flying – which does make it a little awkward to see. Like many other raptors it takes a long time for vultures to reach adulthood. Most of these birds won’t start breeding until they are 6 or 7 years old. In line with this it takes a long time for them to gain their adult plumage. The photo below shows a bird with distinctive streaking to its breast feathers marking it as an immature bird.
IchneumonidaeFollowing on from the ‘mud dauber-mimicking ichneumon’ in the February newsletter, here is another member of the ichneumonidae family of wasps. Wikipedia gives a figure of about 25 thousand recorded species within the family which theyindicate may be only a quarter of their true species richness. Unlike ‘true’ wasps these ones are solitary, and rather than having a stinger, the females have an ovipositor which they use to lay eggs in their victims. The one to the left is presumably male as no ovipositor is visible. This particular species specialises in paratisizing the young of long horned beetles. At the time this one was photographed there were many others to beseen. With their wings glistening an electric blue in the sunlight they made a rather striking sight whilst flying.
White-backed vultures indulging in a little sun bathing.
Immature white-backed vulture showing off its impressive wing span
Gabunia ruficeps
Mulberry hawk moth (Pseudoclanis postica)With the restriction of movement brought about by the coronavirus, only one visit was made to the farm during the period of this newsletter. Bearing that in mind then hopefully the inclusion of the following sequence of photos, that track the development of a mulberry hawk moth during the period, but not from the farm may be excused. Mulberry hawk moths do occur on the farm but this particular sequence was taken in Johannesburg.
A female moth had enteredthe house one evening andhadn’t been able to find herway out. The result was adead/dying moth on the floorthe next morning with anumber of tiny eggs lyingbehind her. The eggs were inthe order of 1 or possible 2
mm in diameter.The eggs hatched approximately 4 days later revealing tiny caterpillars that were barely visible. Mulberry (Morus alba) and white stink-wood (Celtis africana) leaves were added to their container.It seemed barely possible that such tiny ‘worms’ would be able to eat them but the resultant frass at
the bottom of their container clearly indicated that feeding was taking place.The development of the caterpillars was very varied between the different individuals. In the photo above thisdifference can clearly be seen in the four caterpillars sharing a leaf. ‘Sharing’ here only relates to them being on the same leaf. The individual caterpillars showed no good will to their siblings, indeed they seemed actively aggressive when touched by another worm. The number of leaves added to the container had to be increased
dramatically as one caterpillar seemed to havea sudden spurt of growth (above). A day afterthis it started to change colour (right) and tobehave in an unusual manner – crawlingrapidly round and round the container as iflooking for something. As it turns out it waslooking for some earth in which to dig prior tobecoming a chrysalis. Rather strangely having
dug into thesoil itsubsequently came back out prior toforming a chrysalis.The development of the chrysalis’ likethe caterpillars seemed to vary a gooddeal but generally took in the order ofone week. Unfortunately theemergence of a moth from its chrysaliswas never observed. However thedevelopment of the newly emergedwas moth was and resulted in thefollowing sequence of photographs.
30 Jan18 Feb
1 Mar
1 Mar changing color
20th 5th March
The first indication that a moth hademerged was the noise of it scurryinground the bottom of the box into whichit had ‘hatched’. As soon as a suitable
twig was place in the box, the hatchling climbed up it and and hung to the edge of the box where it spent the next hour and a half expanding and remodelling its shape into its true adult form:
20:08 – 14 minutes
19:54
20:00 – 6 minutes
20:01 – 7 minutes
20:03 – 9 minutes
20:04 – 10 minutes 20:05 – 11 minutes
20:06 – 12 minutes 20:06 – 12 minutes
The expansion of the moth’s wings happened rather too slowly to be easily seen whilst watching it. Indeed, this sequence of photos actually gives a much better idea of what was happening than ‘being there’. However, after a little more than an hour had passed a more abrupt movement was noticed and in a matter of seconds the moth suddenly flipped its wings out flat into what my be considered to be their more usual position. After this brief period of movement it lay absolutely still
again for a further 30 minutes. To all intents and purposes it looked fully formed but showed no inclination to fly off. At that point the photographer left for home leaving the moth to its own
devices. The following morning found the moth gone, having presumably flown off at some point later that evening.
Elfin Skipper
To have a butterfly appear in one of the houses duringthe evening rather than a moth is quite an unusualoccurrence, perhaps one in a few hundred or eventhousand visits turns up a butterfly. This particularspecies has a number of hyaline (transparent) patches inits wings – the single spot in the rear wings beingdiagnostic. Unlike many other butterflies this one usuallysits with its wings outspread – not unlike a moth inaspect. “Insects of South Africa” indicates that it prefersrain forest and less commonly savannah woodland. Elfin skipper Sarangesa motozi
Starting form21:04 - 70 to 100 minutes Parent moth
Ermines.
One of our smaller moth visitors,the ermine to the left turned up onthe same evening as the skipperabove. At a casual glance thedifferent species of ermine can allappear very similar. However, acloser looks reveals that there areindeed a number of differentspecies. The photos to the right areof two of those species that havemade appearances on previousvisits to the farm.
Spotted sugar ants
These ants form small colonies of just a few hundred usuallyfound under rocks or other surface debris – as was the case here. They are mostly nocturnal coming out after dark to feed on an omnivorous diet but with a preference to the sugary exude “honey dew” produced by aphids. Indeed, to ensure a continued supply of this substance they will actively defend “their” aphids leading to the term aphid farming. Unlike some other ant species they do not sting, however, they will both bite and squirt formic acid when the occasion demands. Formic acid actually takes its name from the Latin name for ant “formic”, with all ants falling under the family of formicidae.
Green milkweed locust.
Known for their habit of forming large swarms whenthe conditions are right. As adults they feed on citrustrees but also poisonous bushes including milkweed(Gomphocarpus fruticosus) and poison bush(Acokanthera oppositifolia). It’s probably from thelatter food sources that it manufactures the toxic foamthat it exudes via its thoracic joints when threatened.Apparently human fatalities have been reported aftereating them!
