Wednesday, October 29, 2008

Silk the New ADT?

Metalmark moth caterpillars, Brenthia monolychna, build protective shelters out of silk on the leaves that they live on. According to this new research these caterpillars can detect tremors in their webs caused by different objects, previously a behavior only known to be present in spiders. However this new study has found out that these caterpillars are able to build a “security system” with their shelters, including an escape hatch.

The study suggests that they are using the threads in the silk shelters like tripwires, which will notify the moth caterpillar of any disturbance that occurs. In case of an intruder, they have an escape hatch. These escape hatches are small holes beneath the shelters that the larvae made during the construction of the shelters.

Jadranka Rota and David Wagner set up an experiment in which they videotaped the behavior associated with different disturbances. They brought eighteen caterpillars into the laboratory, allowed them to spin their shelters, and half of the shelters were taken away. They then proceeded to tap the silk strands of the shelters or the area where the removed shelters were once connected. They also tapped the edge of the leaves and the caterpillars themselves in order to see if there is a different response. When the silk strands or the caterpillars were touched, the caterpillars escaped through their escape hatch, while when those areas where the shelters were removed were tapped, the caterpillars did not react. This suggests that they do in fact have a “security system” in place, protecting them against most danger.

The researchers are hoping that this study will lead to clues on the evolution of the animals that detect intruders with silk. This study has shown that spiders and caterpillars had independently evolved the ability to use their silk as a predator detecting system.

Posted by Katie Cole (7)


At 5:11 PM, Anonymous Anonymous said...

The title is creative and I like it even though I didn't make the connection with silk and ADT homeland security after reading the blog. I wasn't quick to know what you meant by ADT.

What part of the moth caterpillar's anatomy detects the disturbance that occurs? Do the caterpillars move into their escape hatch all the time when they detect a tremor in their webs from the silk strands of the shelters? Is there a system where they do not react to certain frequencies of tremors?


At 7:40 PM, Blogger PWH said...

thats interesting, so they abandon their territory when a predator comes, will they return?

At 10:58 PM, Blogger PWH said...

It is really neat that they have made this security system. When they use the escape hatch where does it go to? Other leaves? Also, if they remove part of their shelter does it ruin the whole system or is it only the part that they remove that won't work?

-Tara Quist

At 12:21 PM, Anonymous Anonymous said...

This is very interesting, i was wondering if they can tell a danger from a real predator or just environmental cues, like d they ave a filter in place for the security system they build. Also, how often is this to be built, every night or do they return to the same one?

Amanda Joyce

At 1:48 PM, Anonymous Anonymous said...

Very interesting article. But I would have thought that spiders and caterpillars both inherited this ability from a common ancestor. How do they detect the disturbance? Is there some sort of frequency threshold that if the disturbance is above the threshold, the caterpillar will detect and hide?

Hanbing Guo

At 6:42 PM, Blogger PWH said...

very interesting, how can they tell whether there is a predator around or if its just some other insect that is not a predator?
cool title by the way !

Hessom Minaei

At 7:21 PM, Anonymous Anonymous said...

To bad the article doesn't mention what, if any, the function of the long hairs have during the moth phase of its life or even if the long hairs are retained during its metamorphosis?

Allan Eldridge

At 9:55 PM, Anonymous Anonymous said...

What are predators of the caterpillar? I picture a predator that is really slow if it cannot catch up to a caterpillar, even if the caterpillar has an intruder alert system. I never thought of caterpillars as elaborate web builders like spiders. Great post.

-Jordan Grinstein

At 11:06 PM, Anonymous Anonymous said...

took me a second to put that tougher but creative title. also an interesting article. i would have never figure they could do that.

-Matthew Sousa

At 8:10 PM, Anonymous Anonymous said...

ADT is a home security system many people around here use to protect their homes, and like ADT, silk acts as a security system to protect them.

The caterpillar keeps a couple really long hairs in contact with the silk shelter, enabling them to detect a disturbance. The article did not specifically mention if they move into their escape hatch all the time with any kind of tremor, but in their study they found that every time they created a disturbance the caterpillar would use that route. I would say that most times they would, unless say it was just a disturbance from the wind. Perhaps they also rely on sound cues as well, which would help identify potential predators and just normal occurrences like the wind blowing. I would say that the long hairs are lost during metamorphosis, but unfortunately I could not find out any information online about it.

When they use the escape hatch, they end up on the other side of the leaf, and may continue on to other leaves. When they remove the shelter, they remove all of it, from my understanding of the article. They do not leave anything, so basically the caterpillar is just hanging out on the leaf with nothing protecting it.

From the very little information about these shelters online, I assume they are used until they complete their caterpillar phase. According to, Larvae drop onto the leaf litter to pupate before emerging as winged adults. Other caterpillars then move into the freed-up homes and keep up the maintenance of the structures.

The article did not mention anything about a frequency threshold, but I think that is one of the next thing they should study with this subject. A lot of you mentioned about how they are able to distinguish between predator and just normal environmental conditions, and if there is anything special that is transmitted. My guess is this is an interaction of many things, including sound.

From what I know of caterpillars, their predators can include birds, various rodents and spiders. I think that the escape route works well for the avoidance of birds, because they usually do not look under leaves for their food, so it allows for the caterpillars to survive.

Posted by: Katie Cole


Post a Comment

<< Home