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Australian Orchids

Assassin Bugs are predators of Dendrobium Beetle :)
Assassin Bug  Assassin Bug 3 
Assassin Bug 3  Assassin Bug 3 

Assassin bugs

Endemic to Queensland and parts of New South Wales. They have an elongated body with grasping forelegs and a pronounced head equipped with a powerful proboscis for stabbing their prey. Several kinds of assassin bugs may be found in crops but no single species is regularly abundant. Assassin bugs have a lengthy lifespan and during their development consume significant quantities of prey.

Scientific name

Various species of the Reduviidae family


Adults range from 10-30 mm in length, and have distinct heads with prominent eyes; their abdomens have a slight waist. The head is elongated with a long curved 'snout' (proboscis). The proboscis is curved only in predatory bugs. Colour is variable, but usually includes brown, orange and/or black. The front legs are enlarged to grasp prey and the back legs are long and slender. The nymphs resemble adults but do not have wings.

The eggs are barrel-shaped and laid upright in clusters or rows on the leaves or stems of plants. Eggs hatch within two weeks and the wingless nymphs pass through five growth stages before reaching adulthood. As adults, assassin bugs may live for a further 6-10 months and lay up to 300 eggs in rafts of 30-60 eggs.

Similar species
Pests attacked

Assassin bugs feed on many different insects, but tend to prefer softer-bodied prey such as caterpillars and small bugs such as green mirids.

Impact on pests

The stylet-like mouthparts pierce the prey insect and inject an enzyme that dissolves the inner organs. The resultant 'soup' is sucked out, leaving behind an empty shell. Assassin bug nymphs have large appetites and can consume up to 160 small to medium-sized heliothis larvae over a 9-12 week period.

Tolerance to pesticides

The tolerance of assassin bug nymphs to some commonly used products sets them apart from many other highly sensitive natural enemies. Research has indicated:

  • Low toxicity: Helicoverpa NPV, spinosad, indoxacarb, pyriproxyfen.
  • Moderate toxicity: emamectin benzoate, carbaryl, esfenvalerate
  • High toxicity: deltamethrin, maldison, omethoate, methidathion, chlorpyrifos, methomyl, cypermethrin, imidacloprid.

Fiprinol was found to be only slightly toxic when used at rates of 0.0625 L/ha or below.

  Suggested reading

  • Grundy PR 2007. Utilizing the assassin bug, Pristhesancus plagipennis (Hemiptera: Reduviidae), as a biological control agent within an integrated pest management programme for Helicoverpaspp. (Lepidoptera: Noctuidae) and Creontiades spp. (Hemiptera: Miridae) in cotton. Bulletin of Entomological Research 97, 281-290.
  • Grundy PR 2004. Impact of low release rates of the assassin bug Pristhesancus plagipennis(Walker) (Hemiptera: Reduviidae) on Helicoverpa spp. (Lepidoptera: Noctuiidae) and Creontiadesspp. (Hemiptera: Miridae) in cotton. Australian Journal of Entomology 43, 77-82.
  • Grundy PR & Maelzer DA 2002. Augmentation of the assassin bug Pristhesancus plagipennis(Walker) (Hemiptera: Reduviidae) as a biological control agent for Helicoverpa spp. on cotton.Australian Journal of Entomology 41, 192-196.
  • Grundy PR & Maelzer DA 2002. Factors affecting the establishment and dispersal ofPristhesancus plagipennis Walker (Hemiptera: Reduviidae) nymphs when released onto soybean, cotton and sunflower crops. Australian Journal of Entomology 41, 272-278.
  • Grundy PR, Maelzer DA, Bruce A & Hassan E 2000. A mass-rearing method for the assassin bug Pristhesancus plagipennis (Hemiptera: Reduviidae). Biological Control 18, 243-250.
Assassin Bugs from Queensland Government Department of Agriculture and Fisheries website


Taking Orchid Photographs

Taking good orchid photos doesn't require anything special. Lots of people will either already have everything required, or they will be able to buy it all for less than $50, assuming that they already have a camera. You will need:

1. A strong light source. I'll cover the specifics below, but it can be a continuous light or a flash, as long as the flash can be removed from your camera.

2. A tripod. This is very important! The only exception is if you're using flash in an otherwise dark environment. In that case you can get away with hand-holding your camera.

3. A backdrop, if desired. Dark cloth is handy—a dark towel, tablecloth, or sheet. I've used a black T-shirt in a pinch. If you want to spend the money, you can buy a piece of black cloth at your local fabric store. Black velvet is ideal.

4. Something large and white. I'll discuss this in more detail later.

5. Your camera's instruction manual, unless you're already very familiar with the camera's controls.

There are plenty of other pieces of equipment that could make the job easier, though, and I'll mention them along the way. And of course, it does help to have some nice looking orchids!

Lighting Theory

With most orchids—and indeed, a lot of other subjects—the most flattering light is soft and diffused light. This may not be the most artistic light (dark shadows are sometimes used for artistic effect), but it's great for providing an accurate rendition of a subject, and can also be modified for more artistic work, once you get the hang of it.

So how do you get soft light? Contrary to popular belief, it has nothing to do with the amount of diffusion material covering the light. There is a simple rule for getting nice, diffused light:

The larger the light source relative to the subject, the softer the light will be. 

Take a look at the diagram to the right. The first light source is a bare flash tube, which is quite small. All of the light is coming from in front of the ball, so the shadow cast  has sharp edges.

In the second instance, a piece of diffusion cloth is placed between the flash and the ball. When the directional light from the flash passes through the material, it spreads out in every direction, like ripples from a stone thrown into a pond. This makes the illuminated area of the diffusion cloth the new effective light source, and that area is larger than the flash tube, but more importantly, slightly larger than the ball. This allows the light to travel around the edges of the ball and fill in the shadow's edges, making it softer.

hard vs soft light diagram










In the third case, the diffusion cloth is further from the flash, so its illuminated area is larger, and that area is closer to the ball, so it is also relatively larger. Since the light source is so large, a lot of light can pass around the ball and fill in the shadow cast by the light coming from the center of the cloth, making the light very soft. 

Lighting Practice

So, how do you get a big light source?

In photography studios, we use softboxes, silks, and umbrellas to diffuse light, but not everyone has these things handy at home.

You could start by using lights that are big. Fluorescent tubes in a shop light are usually four feet long, which can create very soft light—but only in one direction. However, if you prop or hang the shop-light fixtures vertically and use two or more tubes spaced 2 – 4 feet apart from each other, and about the same distance from the subject, the light should be nice and soft. Be careful, though, because the tubes can sometimes produce hot spots and odd, linear reflections.

A better method is to use a single bright light, such as a 500+ watt halogen work light (about $20 at your local home-improvement store, including light stand) or even a CFL floodlight. Instead of pointing the light at the subject, though, point it in the opposite direction, at a large white object such as a white painted wall. The illuminated portion of the wall—in an otherwise dark room—will become the effective light source, and depending on your working distance, this may be 8 feet tall and just as wide, which will give you very creamy, soft light. It is important to distance the light far enough from the wall so that it spreads out and covers a large area on the wall.

If you don't have a white wall, then you can hang a white sheet on a wall—or freely from the ceiling, for that matter—and use that as your reflector. Just keep in mind that if you use something that is not entirely white, the reflected light will pick up the other colors present, and disrupt the accuracy of the color in your photo. The same strategies work with a flash. Most modern flashes have swivel heads that can be flipped 180 degrees. This is the time to do it! Flip the head back and bounce the flash off your white surface.

If you have a separate flash for your camera, and don't mind spending a little money on specialized equipment, there's a more convenient option. Simply buy a light stand ($19.99), a swivel mount ($25), and a shoot-through umbrella ($15). Most DSLRs these days can trigger the flash when it's off the camera, via infra-red signals. So in most cases, special triggering devices like Pocket Wizards are not necessary. Simply attach your flash to the cold-shoe on the swivel mount, the umbrella to the swivel mount, the mount to the light stand, and start experimenting. To get the softest light, get the umbrella as close to the blooms as possible, while keeping it out of your picture.

Alternately, you can use a light-tent. A variety of sizes are now available, many of them very affordable. Several articles on B&H Insights already describe their use, so I won't repeat the information here. Light tents will not be usefull for large specimen plants or those with tall spikes of blooms, but they'll be perfect for small- and mid-sized species.

Exposure Compensation

If you use either a plain-white or plain-black background be careful about your exposure settings.

When you're using a black background, your camera's meter will often over-expose, making the background grey, rather than black, blowing out the highlights of your bloom. With a white background, the opposite will occur; the white is under-exposed and becomes grey, while the bloom is lost in muddy shadows.

How do you correct this? Use exposure compensation! This might sound technical, but it's nothing more than adjusting a slider to make your picture darker or lighter. Pull out your camera's manual and look up exposure compensation, if you don't already know how to use it. Most cameras allow you to adjust up or down in half steps, some of them in 1/3rd steps.

The nice thing about digital is that you can experiment until you get it right, without worrying about wasting film. If your frame is dominated by the black background, you'll usually need to subtract about 2 f-stops (-2 on your camera's exposure-compensation scale), and if the frame is dominated by white, you'll need to add two (+2). After you're done, don't forget to return this to zero, or all of your future pictures will be over- or under-exposed!

If you have a DSLR, exposure compensation is usually much easier. All of the Canon EOS cameras (except for the Rebel line) have a large thumb dial on the back of the camera (shown here on the Canon 60D) so you can quickly add or subtract exposure. Nikons usually have an exposure-compensation button easily accessable near the shutter-release button, which is used in conjunction with the main control dial.

Additional Tips

Once you get the lighting and exposure right, the rest is pretty easy. Here are some final tips to help you get the best results!

If you can, shoot RAW, and take a photo of a reference (like the white object) to set the color balance. If you're taking JPGs, then it's very important to set the white balance in your camera. Use the instruction manual and your white surface to do so. Better yet, use a color reference card, like an X-rite Color Checker Passport, to get your colors perfect.

1. Keep your black background at least a couple of feet behind your subject. This does two things: It throws it out of focus, so that dust or texture doesn't become a problem, and it makes the background darker, since less light will be reaching it.

2. Always use a tripod! It's critically important when you're not using flash, but it can help even when you are. Not only does this give you the flexibility to use longer exposures, but it allows you to get your body out of the way so that you're not blocking the light!

3. Use a remote shutter release, either radio or cabled. If you don't have one, set your camera's self timer! This will ensure that your camera is absolutely still when the shutter releases.

4. If you're using an SLR, use a smaller aperture (a larger aperture number, e.g., f11 instead of f5.6), but not too small, or your lens may start getting slightly blurry. Avoid the highest and lowest apertures.

5. Introduce additional interest by misting your bloom with water. Droplets can add an interesting texture, and help indicate the scale of your photo.

6. Take photos from unusual angles. This is a good idea with any type of photography, but it's something that is sometimes overlooked with flowers. Also, try experimenting with lighting from different angles (bounce the light off of a white ceiling instead of a wall, or use a wall that's next to the subject, instead of in front).

Camera Considerations

When you know how to use them, many of today's advanced point-and-shoot cameras will be able to produce photos equal to—or better than—the quality of those used in this article. Most of the photos in this article were taken with a six-year-old, 7-megapixel point-and-shoot camera.

However, if you want to take advantage of the exquisite quality available from today's DSLRs, you might consider using a macro lens as well. For Canon's APS-C bodies, their 60mm f/2.8 macro lens is extraordinarily sharp. If you have a Nikon, their 60mm f/2.8 micro lens is also outstanding. Both lenses allow you to focus much closer to your subject than any of the photos presented here, allowing you to express your creativity and capture greater detail.

Good luck, and feel free to let me know if you have any questions. You can check out Gore Photo and Light and Matter to read and see more of my work.



ANOS Warringah group orchid hints