Giant Golden Orb Weaver Rearing

On August 30th, I received several baby giant golden orb weaver spiders (Trichonephila clavipes) from a local museum where I volunteer. These particular ones were given to me because they were refusing to eat. I attempted to force-feed them, but the picky eaters all died despite my best efforts. The last one, however, happily began construction of a web in the corner of my room. For a short while, I had issues feeding her, yet when I realized that moths actually stuck to her web, feeding became much easier. Light trapping could now serve yet another purpose: to catch food for this little spider. Certain species of spider require a specific humidity level to optimize the effectiveness of their web, and I hope that the heater this winter does not dehydrate the air excessively for her.

The temperatures have become too low to catch large moths, but fortunately, black soldier flies (Hermetia illucens) also stick in this type of webbing easily. Someone who rears these flies in massive quantities for composting gave me some larvae, numbering at least several hundred, in the middle of September. While I could have done a better job with rearing these flies, they have still been developing to adulthood properly and are my spider’s new favorite food. I may have to look to find a supplier of these flies overwinter because they require warm temperatures and generate a smell that will likely prove too much for indoor rearing.

I have yet to measure the humidity of my room, but Spider Pharm (the original source that my spider came from) suggests that they require an above-average humidity and temperature. Regardless, mine has molted properly, and, as previously mentioned, the web has been functioning properly. Two possible consequences of an improper environment have not manifested.

As of November 1st, the spider was returned to the museum for their exhibit. Due to my success with this first spider, the museum gave me another spider to raise. Out of the babies I could choose from, I picked a young female that had fallen during its last molt and bent all her legs. Despite these injuries, the spider is still able to maneuver when she is placed on a proper web, such as the one crafted by my last spider in the corner of my room. She is still somewhat challenging to rear, however, as she cannot move as quickly to capture the insects I put in the web before those insects have a chance to escape. She also seems to be exceptionally timid, possibly as a response to her disability. This becomes a problem with feeding as these spiders are incredibly talented at determining what is in their web. If I try to place an insect in her web with the tongs, then she detects the difference in the vibrations from this insect and refuses to come eat. Eventually, a struggling fly will attract her attention, and she will overcome her fear, provided I keep the tongs still.

These spiders can be bred in captivity and are such interesting captives, so I may reach out to the original source of this spider, the aforementioned Spider Pharm, and see about getting a male. Their website currently lists males as out of stock, but if my current spider is able to fix its deformities when it molts next and the museum does not need her for their exhibit, then I will need a male for breeding. There is a paper linked on the Spider Pharm page that outlines a method for rearing large numbers of young orbweavers. If that method works (and based on the good things I have heard about this company, it will), I will be able to supply the museum with spiders for their exhibit. These spiders have also been nice for dealing with escaped flies in the room. I might put some of the males out in my greenhouse if I do not need them for breeding as they seem to be the right size for controlling a number of the pests in my greenhouse. For obvious reasons, I would not want to put females out in the greenhouse as they are not native to my area.

True spiders in general are lacking popularity relative to their cousins the tarantulas, and certain care requirements dissuade prospective keepers from pursuing orbweavers as pets. Nevertheless, these spiders can make amazing pets and have been decently easy to care for in my experience.

Drosophila as Feeders

Flightless Drosophila fruit flies are common feeders for small insectivorous pets, such as dart frogs (Dendrobatidae). They are also essential for raising many species of mantids in any sort of quantity. Two species within the genus Drosophila are often used as feeder insects: D. melanogaster and D. hydei. The main difference is size. D. melanogaster is slightly over 1/16th of an inch, but D. hydei are about 1/8th of an inch. Both are popular feeders and are sold by some of the vendors in the links section. There are other feeders that are the proper size, but they are more cumbersome to raise. The other feeders are impractical to breed in large quantities, whereas fruit flies are easy to breed. I only know of a few published recipes for raising these as pet food. Most people seem to choose to purchase media mixes from major fruit fly suppliers. I think many people would prefer to make their own media if they had a recipe. I have a recipe that works well. It is not quite as productive as the commercial mixes, but I find that it tends to produce a steadier supply of flies over a longer period of time. I have had cultures last for two months and constantly have hundreds of flies.

The cups used to culture flies are important. I use the vented lids from Josh’s Frogs in combination with 32oz deli cups. Unfortunately, Josh’s Frogs recently modified their vented lids. The new lids have thicker plastic and their logo, but the holes are slightly larger. The hole size is not a problem when keeping most insects in the cups, but the larger holes allow other types of flies into the fruit fly cultures. These other flies can wreak havoc on the culture by out-competing the fruit flies. Unlike the fruit flies, which are flightless, these invaders fly and are extremely annoying. To prevent other flies from invading the culture, I have put fabric lids on top of the vented lids. The vented lids provide the proper amount of ventilation and are easier to clean than the fabric lids (flies make a mess of their culture). The fabric lids keep the pests away. It is annoying to have to use two lids and makes the enclosures harder to stack, but at least there are no invading flies. I have shared my observations with the Josh’s Frog’s staff, so hopefully, the old lids will become available again. I would like to have both available because, while the new lids are bad for fly cultures, they are great for other pet invertebrates. The thicker design of the new lids makes it harder for beetle grubs and other strong-jawed pets to chew their way out.

Here is the recipe for fruit fly media:

  • 500 ml beer
  • 200g Mashed Potato Powder

Mix together until smooth

  • 100 ml White Vinegar

Mix again, and add water or potato power to perfect the consistency. It should be like a soft paste.

  • 1 tsp Active Dry Yeast
  • 3 tsp Methyl Paraben

Mix thoroughly and put into fly cups or refrigerate as one large batch.

This media works for either the D. melanogaster or D. hydei. The only ingredient that is not readily available (for most people) is methyl paraben. Its role is a mold inhibitor, and Josh’s Frogs sells it here. They sell it by the pound, which is sufficient for many dozens of cultures. The vinegar is also a mold inhibitor, but the methyl paraben makes a huge difference. This media can also take additives. For example, since I raise mantids with my flies, I often add bee pollen as it is rumored to be beneficial when incorporated into a mantis’s diet.