Net Casting Spider: All You Need to Know in a Nutshell

The Net Casting Spider is a fascinating species known for its unique hunting techniques. As the name suggests, these spiders create intricate, web-like nets to catch their prey. They belong to the Deinopidae family and are often found in tropical and subtropical regions across the globe.

One peculiar feature of the Net Casting Spider is its large, forward-facing eyes, which help it see in the dark and locate its prey with precision. These spiders are also known for their ability to change color, blending in with their surroundings for camouflage. Additionally, Net Casting Spiders exhibit remarkable agility and speed while hunting, making them effective predators within their ecosystems.

Net Casting Spider Overview

Physical Features

Net casting spiders, also known as ogre-faced spiders, belong to the family Deinopidae. Their most distinguishing feature is their large, forward-facing eyes, which give them a distinct “ogre” appearance. These spiders also possess:

• A body size of approximately 0.4 to 0.8 inches (1 to 2 cm) in length
• Long, slender legs
• A unique “net casting” hunting technique

Distribution and Habitat

Net casting spiders of the genus Deinopis can be found across various continents:

• Australia
• USA
• Africa

These arachnid species typically inhabit areas with vegetation such as forests or gardens. Here is a brief comparison of some common net casting spider species found in different regions:

Net casting spiders have specific adaptions to match their surroundings, making them effective nocturnal hunters.

Hunting and Prey Capture

Unique Net Technique

Net casting spiders have an exceptional hunting strategy. They create a small rectangular net with cribellate silk using their legs. This net has the following features:

• Silk material
• Rectangular shape
• Made using spider’s legs

Here’s a comparison of the three different types of spider webs:

Night Vision and Sensitive Eyes

These spiders are known for their highly sensitive eyes and excellent night vision. They have the following advantages:

• Operate at night
• Detect prey in low-light conditions
• Increased hunting success

Diet and Types of Prey

Net casting spiders feed on different types of prey, including:

• Insects
• Beetles
• Flies

Their efficient hunting strategy helps them capture prey on surfaces like leaves and tree trunks. The accuracy of prey detection comes from their remarkable night vision and highly developed sense of hearing.

Reproduction and Life Cycle

Mating Process

Net casting spiders have an interesting mating process. The male spider approaches the female cautiously to avoid being mistaken as prey. They perform a courtship dance, tapping their legs on the female’s web.

Egg Sacs and Spiderlings

Female net casting spiders create egg sacs to protect their offspring. These sacs are:

• Round or oval-shaped
• Made of silk
• Usually camouflaged

The spiderlings hatch from these egg sacs and disperse. They are miniature versions of adult spiders, but are harmless and cannot harm humans.

Growth and Longevity

Net casting spiders go through a growth process called molting. Key points about their growth and longevity are:

• Molting allows them to grow larger and replace damaged body parts
• They molt several times before reaching adulthood
• Adult lifespan varies among species, typically lasting 1-2 years

Behavior and Adaptations

Nocturnal Lifestyle

Net-casting spiders are active during the night due to their nocturnal nature. They thrive in environments with lower light levels.

• Example: These spiders blend into their habitat at night, making them even more elusive.

Predators and Defense Mechanisms

• Predators include birds, lizards, and other larger spiders.
• Defense mechanisms involve their ability to sense vibrations and escape potential threats quickly.

Camouflaging and Unique Body Features

• Camouflaging involves disguising themselves among leaves and twigs.
• Unique body features include their specialized spinnerets and hairs.

Comparison Table

Example of Net-Casting Spider Features

• Specialized spinnerets for unique web designs
• Sensitive to light for nocturnal activities
• Utilizes camouflage for effective predation

By understanding the unique behavior and adaptations of the net-casting spider, we can appreciate the fascinating aspects of this often mysterious creature. While its nocturnal lifestyle may be similar to other spiders, its camouflaging abilities and distinctive body features make it a noteworthy subject in the world of arachnids.

Net Casting Spider Species

Deinopis Subrufa

Deinopis subrufa, commonly known as the Australian Net-Casting Spider, is a unique species found primarily in Australia. This spider is known for its distinctive hunting technique, which involves creating a small, silk net and casting it over its prey. Notable features of Deinopis subrufa include:

• Large, forward-facing eyes with excellent night vision
• Legs that are adapted for grasping its capture net
• A body that grows up to 25 millimeters in length

Menneus

Menneus is another genus within the Deinopidae family, which includes net-casting spiders. While less known than Deinopis subrufa, Menneus spiders also use a similar net-casting technique to catch their prey. Key characteristics of Menneus species are:

• Long, slender legs suited for net grasping
• Presence of unusual plate-like scales on their bodies
• Typically found in Australia and the southwestern Pacific region

Other Species

There are several other species within the Deinopidae family, all of which exhibit net-casting behavior. Though their appearances might differ, these spiders share certain traits such as:

• Excellent vision and nocturnal hunting habits
• Unique net-casting techniques for prey capture
• Inhabiting regions like Australia, Africa, and the Americas

Comparison Table of Net Casting Spider Species:

Net Casting Spider Evolution and Research

Evolution of Night Hunting Behaviors

Net casting spiders have adapted to hunting in low-light conditions. Their unique hunting techniques enable them to capture prey at night, making use of specialized web structures. Some notable features of their night hunting behaviors include:

• Exceptional night vision
• Ability to sense vibrations from prey
• Use of sticky, specialized webs for net casting

Scientific Studies on Vision and Habitat

Researchers at Cornell University have conducted studies on spider eye development and evolution, providing insights into the vision of net casting spiders. They have identified promising candidate genes and gene networks that may play a significant role in their vision adaptations. Understanding their vision helps scientists determine how they thrive in specific habitats.

Role in Ecological Communities

Net casting spiders play an essential role in maintaining ecological balance. As predators, they help control the populations of insects and other small arthropods within their habitats. Additionally, they serve as a food source for larger predators, such as birds and mammals, contributing to the overall health of their ecosystems.

Reader Emails

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.

Letter 1 – Net Casting Spider

CAN YOU NAME THIS PLEASE?
Hello,
Can you please help my wife and I tell our 2 year old what this is? It moves like a spider and has 8 legs but doesn’t spin a web, or eat flies. It has eyes like a stick insect I saw on you site, but is unlike anything I hae seen before. We live in Melbourne, Australia and our son found it on our front door. Any help would be appreciated. Kind regards
Garry Yeomans

Hi Garry,
This is a Net Casting Spider in the Family Deinopidae. We located a great site with information. According to the site: “Net-casting Spiders have a unique way of catching their prey. They make a small web in the form of a net held by the front legs that can be stretched out wide to envelop an unwary insect passing by.”

Letter 2 – Netcasting Spider from Australia

Subject: What’s this strange spider?
Location: Australia, Melbourne
February 16, 2013 12:32 am
Hi
I am from Australia, and as I opened my garage door on a hot summer day I noticed this creature on the door. Initially I thought it was a twig as it remained stationary, but it began crawling upwards once I pulled the door down; completely to my surprise. It appears to me like some kind of spider, but I can not be sure. Could you help me?
Signature: Bo

Hi Bo,
This is a Netcasting Spider,  probably Deinopsis subrufa and judging from the size of the pedipalps, it is most likely a male.  The website Where Light Meets Dark has a very nice profile on this species.  More information be found on the Spiders of Australia website.  Jennifer Marohasy’s websitehas some great photos that show how the Netcasting Spider got its common name.

Alright, thanks for the help!

Letter 3 – Male Net-Casting Spider from Australia

4 legged spider
Location: Sydney, Australia
January 5, 2011 6:25 am
Hello
This has me stumped. Never seen anything like it!
Looks a bit like a spider. Hangs around on the wall like a spider.
Seems to have a thin long body and 4 legs that spread diagonally.
WTB??!
Signature: Sincerely Jonathan

Hi Jonathan,
We do not recognize your spider and we are posting your letter as Unidentified since we haven’t the time to research this at the moment.  Perhaps one of our readers will have some luck.  You may also try scanning through the Spiders of Brisbane webpages.  There are some spiders that rest with two pairs of legs together, creating the appearance of four legs rather than eight, and this specimen appears to be one of those.

Identification courtesy of Karl
Hi Daniel and Jonathan:
It appears to be a male Net-casting spider (Deinopidae), probably Deinopsis subrufa. You can also check out this site. Regards. Karl

Thanks Karl.  Trevor also supplied us with an identifying comment.

That’s great!  Thank you.
It does look a lot like this one:
http://www.wherelightmeetsdark.com/images/wiki/Netcasting_spider_Deinopsis_subrufa_3.jpg
I reckon that is what I saw or something very close.
Jonathan Young

Letter 4 – Bug Mimicking Swift Spider eats Net Casting Spider in Australia

aussietrev foodchain S picta eats D.ravidus
November 29, 2009
Hi guys,
Hope the book is progressing well. Will you have it for sale on the site? Thought you might like this shot of Suppuna Picta finishing off a male Dinopis ravidus (Net casting spider)
aussietrev
South East Queensland. Australia

Hi Trevor,
Nice of you to ask about the book.  Coincidentally, we sent off the first draft today.  Now we wait for the editor’s comments before beginning to rewrite.  We had to correct the spelling on Supunna picta before we could find a link.  Thanks for the great photo.  Interesting that the Bug Mimicking Swift Spider mimics the nymphs of the Gum Tree Shield Bug.

Letter 5 – Net Casting Spider from Australia

Subject:  Four-legged Spider
Geographic location of the bug:  NSW, Australia
Date: 01/12/2018
Time: 07:19 PM EDT
Your letter to the bugman:  Hello Bugman,
Found a four-legged Spider at my fence. When I placed it in a dust pan to put outside it turned out it had 8 legs.
Is this harmful as well?
I keep seeing a lot of spiders lately.
How you want your letter signed:  Carlo

Dear Carlo,
This is a Net Casting Spider in the family Deinopidae.  According to Atlas of Living Australia, they are reported from all over your continent.  According to Australian Museum:  “Net-casting Spiders have a unique way of catching their prey. They make a small web in the form of a net held by the front legs that can be stretched out wide to envelop an unwary insect passing by.”  That site further elaborates:  “Net-casting Spiders have stick-like bodies, with spindly legs. Members of the genus Deinopis have a large, prominent pair of eyes at the front of the head (hence their other common name of Ogre-faced Spiders) and vary in colouring from fawn to pinkish brown or chocolate brown. Members of the genus Avella have smaller eyes and have subtle greenish brown to grey patterning. The males are smaller and even more slender and stick-like than the females, and can differ from them in their colour and patterning.”  Here is some additional information from Australian Museum:  “When at rest, the spider hangs from vegetation with its head downwards, its long body and long, thin front and back legs held together on each side, giving the spider a stick-like appearance. The spider also assumes a head-down position when it is waiting for prey, except that it now holds its net with the front four legs and suspends itself by the back legs and spinnerets from support lines to surrounding foliage. The net is a blueish-white square of wool-like cribellate silk, whose coiled lines are designed to stretch and entangle prey. In order to have an aiming point, the spider often drops splashes of white faecal droppings onto the leaf or bark substrate over which it is poised. When an insect walks across this ‘target’, the spider plunges its net downward to envelop and entangle it. If successful, the spider silk-wraps the prey item, bites and paralyses it, and then feeds on it. Net strikes will also be made at flying insects that stray too close. An unused net is sometimes stored by hanging it on nearby leaves for the next night’s hunting, or the spider may eat it.”

Letter 6 – Netcasting Spider from Australia

Subject: What is this insect?
Location: Perth WA
February 19, 2016 10:01 pm
I found this on my fence outside, there was a spider web around it, but I’m not sure if it came from the insect or anything spider. I tried to search this insect but couldn’t find anything in relation to it, the insect has 6 legs and I’m really curious to know if it is poisonous or not. Thank you hope you can get back to me 🙂
Signature: From Christelle

Dear Christelle,
Though it does not appear to have a net, we believe this is a Netcasting Spider in the family Deinopidae, which is pictured on Brisbane Insects where it states:  ” The species in this family are large and slow moving spiders. They have long body and stick like legs. Their bodies are light brown or grey in colour. They do not build permanent web, instead, they hold the net and throw it towards their prey.”  The Spiders of Australia site has a Deinopidae page where it states:  “The net-casting spider is a common spider and is also often seen in documentaries because of its unique way of catching prey. The spider positions itself, head down, and grasps the rectangular capture net with its four front legs. If a walking insect is detected, the net is pushed over the victim that gets ensnared. Flying insects, like moths, are caught by flicking the web backwards.   The web is made of non-sticky cribellate (woolly) silk. Insects gets entangled in the wooly structure.  The spider relies heavily on its eye-sight. The eyes are arranged in three rows. Two of her eight eyes are extremely large.   The spider is active during the night and during the day she remains camouflaged on a tree bark. Her body length varies between 1.5 and 2.5 cm and they are light rusty brown coloured.” Your individual appears to be missing a leg.

Letter 7 – Netcasting Spider from Costa Rica

Subject: netcasting spider
Location: costa rica Tortuguero
March 27, 2013 12:33 am
do you have the exact name for this species?
thank you
Signature: fred from belgium

Hi Fred,
We are unable to do any research on this Netcasting Spider at this time, but it is really a lovely photo.  Perhaps one of our readers will write in with an identification.  We would urge you to provide a comment on each of your unidentified species on our site and then you will be notified in the future if any experts provide information.

Letter 8 – Ogre Faced Spider from South Africa

Subject: Spider under my pillow
Location: Durban south Africa
December 17, 2016 4:29 am
Hey bugman, I found a spider under my pillow last night and I was wondering if you can identify it for me
Signature: Shane

Dear Shane,
We are relatively confident we have correctly identified this leggy spider as an Ogre Faced Spider in the genus Deinopsis from the Net Casting Spider family  thanks to images on iSpot.  According to BioDiversity Explorer:  “They are harmless to man” and “Deinopids are unique in that they actively use and manipulate a web to capture prey. First a scaffold web is constructed and attached to the vegetation over an area where prey will pass. The spider then positions itself with its head up and using a comb-like structure (cribellum) on the tibia of its hind legs, it combs out cribellate silk from a special silk-producing organ called the calamistrum. The calamistrum is a cream coloured band about 1.5 to 2 mm long and about 0.2 to 0.5 mm wide and is situated anterior to the spinnerets, viewed from below. It consists of 20 000 to 40 000 spigots (silk-producing organs), each producing a very fine strand of silk. The silk is combed out onto the normal silk strands of what will be the capture net and has a woolly appearance. In fact, the silk looks like this as it is in a relaxed form, like a relaxed rubber band and has a 400 to 600% stretch capacity. The rectangular capture net made of this crumpled silk has no adhesive capture ability but relies on entangling properties instead – much like Velcro, where the net tangles with projections on the prey’s body.
When the net is ready the spider re-orientates itself on the scaffold web with the head facing down, grasps the net by the four corners with the four front legs, gives it a few stretches, and then relaxes the net and waits for prey. For walking prey, the net is held horizontally or vertically over the substrate and when flying prey is detected, the net is flicked backwards, over the carapace, still in a vertical or horizontal position. Visual senses are used to detect walking prey such as cockroaches, ants and even spiders but vibration senses are used to detect flying insects, moths being the most common prey.
When prey is detected, the spider propels itself forward, stretching the net further and then suddenly releasing the tension, although not letting go of the net. The net contracts and ensnares the prey. Once captured, the prey is then secured further with silk fed from the spider’s spinnerets with the hind legs. While the scaffold net is reused each night, the capture net is used only once. A new capture net is constructed each evening and in the morning it is simply rolled into a ball and eaten.“

Letter 9 – Ogre Faced Spider

Subject:  Too many bugs pesticide and paid services no help
Geographic location of the bug:  Southern,California 3 miles from Mexico border
Date: 06/16/2019
Time: 02:03 AM EDT
Your letter to the bugman:  We have used many pest control company store bought poison not many big bugs like the pic but thousands of tiny ones inside and out constantly crawling touching then once on a while a bite or sting hot pain for 1/2 second then it starts all over to small to see .they have won I left my home and husband 3 mounts
How you want your letter signed:  Earvey

Dear Earvey,
We do not provide extermination advice, and we empathize with your situation.  That said, we have no idea about the identity of the “spidery” thing you submitted.  You submitted three identical images of this thing.  Do you have any additional images?  How large is it?  Your image is lacking in critical detail, but the eight legs give it the resemblance of a Spider or Tick, but it is unlike anything that comes immediately to mind.  Perhaps one of our readers will be able to assist with this challenging identification.

Update:  Diana posted a comment indicating she believes this looks like a Whip Spider, Argyrodes colubrinus, but the image on Dave’s Garden and the image on Project Noah of that Australian species do not look like the same species to us, so we still consider this unidentified.

Update:  July 18, 2019
We received several comments that this looks like an Ogre-Faced Spider in the genus Deinopis within the family Deinopidae.  Here is a BugGuide image that supports that identification.