Observation of the Week, 5/9/18

Our Observation of the Week is this encounter between a wolf spider and a Tawny Mole Cricket, seen in Louisiana by @audubon23!

“A friend and I were visiting the trails in Couturie Forest in City Park, New Orleans to see which species of birds would be active in mid-April,” recalls Anna (audubon23). They stumbled into a new (to them) area of the park with two large concrete circles, which they later discovered were old model airplane courts (visible via satellite photos).

I noticed the mole cricket sitting out on one of the concrete circles in the middle of the day, [and] I didn’t notice the wolf spider until I bent down because the spider was so comparably small...The spider allowed me to get very close with my camera. There was no way would he relinquish this cricket to this camera lady. He earned it.

What happened here? Mole crickets tend to stay in their burrows during the day, so Anna thinks “that the cricket was out at night or early morning when the spider ambushed and injected its venom, and then the pair sat there together for hours until I discovered them in early afternoon...I would love to have seen the spider subdue and immobilize the cricket. It must have been quite a feat.” Spiders need to liquefy the insides of their prey before consumption, and Anna believes “the spider didn’t even make a dent in liquefying and digesting the cricket.”

One of the more bizarre-looking of the Orthoptera, mole crickets are found over much of the world and are well-adapted to a life of burrowing underground. Their forelimbs are paddle-shaped and excellent for digging, while their back legs are used to pushing dirt rather than jumping. Male mole crickets will even use the entrance of their burrow as a horn to amplify their calls at night, and females will fly to them. Some mole crickets are herbivorous, like the Tawny Mole Cricket, while others are omnivorous or even predatory. Tawny Mole Crickets are native to South America and have become agricultural pests in North America since being accidentally introduced there in 1900. 

Mole crickets face quite a few predators, with wolf spiders being an important one. Unlike many other spiders, wolf spiders do not spin webs. Rather, most amble along the ground and either chase or pounce on prey, while others make burrows underground. They are fast, often nocturnal, and have excellent eyesight. If you’re ever out in the woods in North America and are using a headlamp, look for small yet powerful green eye shine on the ground - these are likely from wolf spiders.

Anna (above) has been interested in nature since her childhood, and “began volunteering at the zoo in New Orleans at age 12 as a ‘Junior Keeper’ in the education department, and I eventually became an intern for their Louisiana wetlands education-outreach vehicle. That helped to further my passion for Gulf Coast wildlife.” She’s a recent college graduate and says she’s “still working out how I want to continue my education and career and what areas of research I want to pursue.”

And of iNaturalist, Anna writes

I use iNaturalist for documenting the wildlife I encounter, and it has really changed the way I interact with the natural world. I pay much more attention to what I see and hear than I used to. I want to identify everything now! It has also made me much more aware of my community’s biodiversity. I am more familiar with what is around me and how it all interacts.

It is wonderful how it connects people of different locations and levels of expertise and experience. I really love the concept of crowd-sourced data collection on wildlife. It really makes me feel like I am contributing to something much bigger than myself. It engages people and actually helps real science. It doesn’t get much cooler than that.

- by Tony Iwane

- Female wolf spiders famously carry around both their egg sacs and their new hatchlings with them as they walk. 

- Meet Steinernema scapterisci, a nematode worm that kills mole crickets (and other hosts) by infecting them!

Posted by tiwane tiwane, May 09, 2018 21:06


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