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Venus flytraps got their name because they feed on flies and other insects. A question new growers might ask is, can these carnivorous plants also eat spiders? Most flytraps eat slugs, caterpillars and flies, but can we include spiders to this list or should we keep the plants away from these?
Venus flytraps eat spiders because they contain nitrogen required by the plant. Due to the size of their trap however, Venus flytraps can only prey on the smallest spiders.
Why Venus Flytraps Need Spiders
Venus flytraps consume spiders and other insects because they are rich in nutrients, specifically nitrogen, phosphorus, sodium, uric acid and potassium. Carnivorous plants use these supplements to fuel their growth and strength.
Why not get these from the ground? Well, Venus flytraps only grow in poor soil. If you want to grow a Venus flytrap, do not use fertilized potting media. You must only use soil made for these plants. A good choice is Jessi Mae Carnivorous Plant Soil because it it specifically for carnivorous plants.
Because the ground lacks these elements, the plants developed traps to catch insects to get their nutrients. Spiders have the nitrogen, potassium and other nutrients Venus flytraps require to flourish. By digesting the insect they end up absorbing the nutrients, similar to how humans absorb vitamins and minerals.
Venus flytraps do not actually eat insects for food. Plants digest food very differently from animals so they do not eat the way animals do.
What Venus flytraps do is make their own food through photosynthesis. Water, air and sunlight make photosynthesis possible. The end product is glucose, a sugary substance which serves as their food. Glucose is what keeps them alive.
Spiders on the other hand, function as supplements or vitamins. Venus flytraps will not die if they fail to eat bugs but it will slow their growth.
While spiders and other insects are not necessary for Venus flytraps to live, it is important if you want them to be as healthy as possible. The nutrients that spiders and other bugs supply is the fuel that drives the plants to produce bigger traps. Venus flytraps digest spiders for the same reason we take supplements to build muscles.
Aside from spiders you can also feed them frozen insects or fish food. They are just as nutritious and will help it grow bigger traps and make them less vulnerable to disease and infection. However you should not fertilize the soil because it will harm the flytraps. They are not used to rich soil and it will not do any good.
What Happens When Venus Flytraps Trap a Spider?
Venus flytraps can live without bugs, but they are better off with them because they provide nutritional value that is hard to come by in the soil. The digestive process is similar for whatever bug falls into its traps.
Venus flytraps produce scented compounds that attract bugs. When a spider is drawn by the scent, they are further lured in by nectar. The nectar is located in the trap, the reddish part of its leaves. When a spider enters the trap, its sensors are triggered. If the sensor is triggered again in 20-30 seconds, the trap shuts quickly.
If the insect does not set the sensor off in 30 seconds or less, nothing happens. The plant developed this mechanism so they do not waste energy on false alarms.
A trapped spider is going to struggle to get out. The trap will squeeze tighter until it is airtight. The plant will release digestive juices to melt the spider, similar to how animals produce digestive liquid in their stomachs.
This is how a Venus flytrap eats a spider. It produces digestive fluids to dissolve the tissues. These melted tissues and digestive liquids are absorbed by the plant and turned into nutrients.
Only the soft parts are eaten by the flytrap. Its hard shell is left over, which is why Venus flytraps cannot eat large beetles and other insects with rigid exoskeletons.
It takes about 5-12 days for a Venus flytrap to digest a insect. Once it is finished, the trap will open again. All you will see are the leftover spider bits (the hard inedible parts) and some liquid goo.
As soon as the trap reopens, the plant is ready for another meal. But even if they are unable to catch any insects soon, they will be fine. As pointed out, a single insect goes a long way.
Can I Feed Dead Spiders to My Venus Flytrap?
Venus flytraps can be fed dead spiders or any kind of dead bug. Put the insect in its trap and stimulate the hair sensors. When the trap closes the plant will commence the digestive process.
Indoor Venus flytraps are usually fed freeze dried mealworms and crickets, but you can also give it a dead bug provided it can fit in the trap.
If the spider is too big, cut it into smaller pieces. Place the bits in the trap and stimulate the hair sensors. The trap will close and start digesting the bug.
You can do this not just with spiders but also gnats, crickets and other dead bugs. You can even feed them Blue Ridge Fish Food Pellets by chopping them into smaller chunks. And the best thing is you do not have to worry about some bug trying to eat through the leaves.
However there are difficulties with feeding dead spiders to Venus flytraps. Unlike mealworms, it is not easy to find them in stores. You might get lucky and find one in your house but it is a long shot.
So while Venus flytraps can digest dead spiders, it is difficult to feed it to them. It is more practical to just let the plant catch live ones instead.
Of course if your Venus flytrap is outdoors you do not have to worry about any of these. You can just let the plant eat whatever insect falls into its trap.
If you happen to have a lot of dead spiders though, feed only one trap. Even a small one is enough to last a flytrap for a while.
And keep in mind that Venus flytraps must have plenty of sunlight, water and air to live. Bugs are a nice addition to their diet, but their real food is still glucose.
How Many Spiders Can Venus Flytraps Eat?
So we have established that Venus flytraps can digest dead spiders. But how many of these can the plant it?
Venus flytraps only need to eat one insect every 1-2 weeks. It takes the plant 5-12 days to digest one bug, and feeding multiple traps could weaken the plant.
Venus flytrap have to use a lot of energy to lure a bug, trap and digest it. If one trap has caught a spider, that should be enough for the next couple of weeks. When the trap opens again you know it is ready for another meal.
You could feed a couple of traps at a time, but it is better to avoid overfeeding it. During dormancy, Venus flytraps do not even need to eat.
The best way to avoid overfeeding is to leave your Venus flytrap outdoors. Place it somewhere with sunlight and keep its soil damp. You do not have to worry about how many spiders or bugs it has to eat because there are lots of those.
Even when outdoors, your Venus flytrap is unlikely to overfeed itself. Check it every now and then and you will see one trap closed. After two weeks o so it will open again, so it only digests what it can.
If your flytrap is indoors, keep the feeding to one insect per two weeks. You can mix and match bugs like spiders, ants, gnats, flies etc. You can also give it freeze dried bloodworms and even some fish food.
The important thing is to make certain the plant gets its required nutrients without going overboard. Fortunately this is easy to remember. Just feed one trap, and do not feed it again until the leaf has reopened.
Knowing what Venus flytraps can and cannot eat is important for its survival and growth. If you decide to feed your plants some spiders, you can rest easy knowing they are part of its natural diet.
My fascination with carnivorous plants began many, many years ago with Venus Fly Traps. Now I am more than happy to impart what I know with other enthusiasts and those who are curious about meat eating plants.