Sand or Thread-waisted Wasps

Predatory wasps are a threat to caterpillars

You may have read other hubs of mine about my efforts and achievements in rearing Monarch Butterlies from caterpillar to adult insects but for the past year I haven't had any success despite a supply of food plants growing here. I think I have found out why though and why there are no female butterflies coming back to lay more eggs.

A predatory insect that I didn't used to see here has become a frequent sight and that insect is a Sand Wasp or Thread-waisted Wasp and it feeds its larvae on caterpillars.

Thread-waisted wasp photos

Thread-waisted Wasp (Podolonia tydei). Photo by Steve Andrews
Thread-waisted Wasp (Podolonia tydei). Photo by Steve Andrews
Thread-waisted wasp searching for food
Thread-waisted wasp searching for food

A killing machine

One of the species we have here on Tenerife is Ammophila tydei (Podolonia tydei) of the family known as the Sphecidae. Its scientific name is in reference to Mt Teide, the mountain central to the island of Tenerife, and the highest mountain in Spain.

It is a large and distinctive insect and an effective hunting and killing machine. The mother wasp has to find enough caterpillars to feed her own young ones with. She flies about looking almost like a mini-drone aircraft as she hovers and flies in straight lines towards targets in her sights.

The mother wasps methodically search bushes and plants if they suspect they may have caterpillars on them. If they find any moth or butterfly larvae they sting them and grab their prey which they carry away to place in a burrow they have previously dug in sandy soil. At least this is what most wasps of this genus do, although the ones I have been watching build nests of mud daubing on walls. A female I watched spent every day for nearly a month doing this on the wall by my balcony.

The wasp Sceliphron spiriflex lives on the island and this species makes a nest of mud. This wasp hunts spiders to feed its young with.

The wasp puts its paralysed caterpillar or spider victims in its nest and then lays an egg. After it has done this it seals it off.

Because species in this family tend to make their burrows in sand and sandy soils they have earned the name Sand Wasp. Their alternative moniker, Thread-waisted Wasp, describes their physical appearance accurately. The body of the insect is carried at the end of a long thread-like waist that continues from the head and thorax area.

There are other closely related species, some of which build nests of mud, such as the aptly named Mud Dauber Wasp.

They are quite large insects over 2cm in length but they will not attack humans despite their somewhat scary appearance. The adult wasps feed on nectar from flowers.

Copyright © 2010 Steve Andrews. All Rights Reserved.

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Comments 30 comments

CMHypno profile image

CMHypno 6 years ago from Other Side of the Sun

Very interesting Hub on sand wasps, Bard of Ely. I'm sorry that you are having trouble attracting the Monarch butterflies back to your garden, but it is always fascinating to read about the intricate relationship between all the insects, plants and animals in any habitat. Hope your butterflies return soon.


Bard of Ely profile image

Bard of Ely 6 years ago from Lisbon, Portugal Author

Thanks, CM! I only have a balcony which doesn't help but I have not seen a Monarch for many months. I think the wasps can take various types of caterpillars and are finding sufficient in this area. They have as much right to life as the butterflies.


Granny's House profile image

Granny's House 6 years ago from Older and Hopefully Wiser Time

Hi Bard, I also love butterflys. You say you only have a balcony, did you ever think of hanging wasp traps? It may help. Just a thought.


Bard of Ely profile image

Bard of Ely 6 years ago from Lisbon, Portugal Author

It wouldn't help because these wasps only seek caterpillars and have clearly been successful away from my balcony having eliminated Monarchs from breeding successfully in the area. So there are now no adult butterflies to come and lay eggs on my plants. Unless a butterfly flies into this area I don't see the situation changing.


fen lander profile image

fen lander 6 years ago from Whitstable

Surely, this is a sign of an imbalance somewhere in the chain? Too many wasps. Have you looked at why the wasps are so successful that they wipe out the butterflies? I reckon it's agro-chem interference? Are there any natural predators on the wasp that are being 'culled' by un-natural mankind? Some humming bird or other insect, perhaps? If that species were helped/reintroduced maybe things would look up for the monarch. I'm quite ignorant about butterflies but find these blogs of yours stimulating. Long live the monarch!


Bard of Ely profile image

Bard of Ely 6 years ago from Lisbon, Portugal Author

There is no imbalance, Fen! There are not many wasps but only a few are needed to take all the caterpillars on a plant. The Monarchs got here by chance and depend entirely on gardeners growing Milkweed and thus the population is always low and is limited not only by the number of places the plant grows but worse, the females tend to plaster their eggs all over plants they can find, which means there is insufficient food and the caterpillars starve. In 'normal' conditions there should be hundreds of Milkweed plants so each female can lay but one egg per plant. This has never been the case here because the plants do not grow wild. The wasps, however, are native to the island and are able to prey on many species so if there are no Monarch larvae they can feed on others. The Monarch only feeds on specific foodplants so is limited by that.If insufficient people such as myself choose to grow Milkweed here and help the butterflies then I suppose they could eventually die out and it will return to how it was before they colonised the island. I tell people to plant Milkweed and try passing on seeds but few people are interested. From an ecologists's point of view the butterfly should never have been here, but then that applies to countless introduced and naturalised species of plant and animal here.


davenmidtown profile image

davenmidtown 4 years ago from Sacramento, California

The toxcity of the Monarch is present in the caterpillars too...Sphecid wasps are also not likely to hunt monarch larvea. Tachinid flies are the primary parasitoid of monarch larvae. Braconid wasps will also sometimes parasitize a monarch caterpillar but not nearly as often as the Tachinid fly. Most sphecids skin the caterpillars that they hunt and since the toxin of the Monarch is found in both the skin of the caterpillars and the exoskeleton of the adult butterfly, the wasps would likely die. Parasitoids eat their host from inside to out and emerge through the skin so are not affected by the toxic nature of the Monarch. Sphecids prefer the caterpillar of the Cabbage Butterly and the Great White Butterfly as food for their nests. Fire Ants are also a prime predator of Monarch eggs. Bacteria, fungus and Viral infections also kill Monarch adults and Caterpillars.


Bard of Ely profile image

Bard of Ely 4 years ago from Lisbon, Portugal Author

Well, I am not sure where you get your info from but you clearly haven't seen what I have here where wasps most definitely predate monarch caterpillars and I would say are their main predator.


davenmidtown profile image

davenmidtown 4 years ago from Sacramento, California

That is what I have been doing is studying entonmology. I stand by my comment. The role of hymenoptera and lepidopera have long been examined as have the parasitoid and hyperparasitoid relationship within the lepidopera field of study. Mud Daubers are Sphecid wasps most of which prey on spiders... though some do prey upon caterpillars. You have also described a situation where the Monarchs are advancing into new territory. That behavior could confuse the wasp who may prey upon the Monarch caterpillar to it's own demise and the demise of its young. That would be rare, but plausible. If you would like to be successful rearing Monarchs, harvest the pupa and raise them indoors. Once in their cyrsilis they will be fine indoors.


Bard of Ely profile image

Bard of Ely 4 years ago from Lisbon, Portugal Author

We will have to agree to disagree! I have seen Milkweed here that I personally put Monarch caterpillars on devoid of them days after and wasps searching them. In agreement with you I have also unsuccessfully reared a monarch caterpillar that was parasitised by a tachinid that hatched. I too stick by my research and observation and I quote David Bramwell's Historia Natural de las Islas Canarias (Natural History of the Canary Islands) with regard to Ammophila teydei: "y alimenta su larva con gusanos de lepidopteros." (feeds on caterpillars of moths and butterflies).

I have actually reared as many as 50 Monarchs in one week by letting the caterpillars pupate in empty plastic water containers indoors. I fed them on Milkweed I had grown or collected.


davenmidtown profile image

davenmidtown 4 years ago from Sacramento, California

Ammophila does indeed feed on caterpillars of lepidoptera...but not all caterpillars. Wasps often search plants to harvest the waxy surface of the leaves... or wax from the surface of the leaves which they use when making nests. The reason that I say wasps are not the primary culprit of the demise of your Monarchs is because the caterpillars eat the milkweed which is toxic. The toxin is housed in the skin of the caterpillar and the exoskeleton of the adult butterfly... that toxin is cyanide. It would kill the wasp that ate it. If you have witnessed the wasp sting the caterpillar... you may be witnessing something even rarer than parasitic actcion... hyperparasitical action in which the parasite (probably the Tachinid fly) becomes the prey of the wasp... in this case the duel would be fought inside the caterpillar.... on a different note: You have a book listed "Bees Wasps and Ants: The Indespensible Role of Hymenoptera In The Garden" This is an excellent book and the photographs are truly stunning.


Bard of Ely profile image

Bard of Ely 4 years ago from Lisbon, Portugal Author

I admit I have never seen a female wasp take a Monarch caterpillar but I have seen Milkweed plants devoid of caterpillars in a short space of time and these wasps searching them so I drew my own conclusions. I also dispute the toxicity of the Monarch and the so-called warning colours. My cat has caught the butterflies several times and I was too late to rescue them. She has chewed and killed them and did not suffer any ill effects or avoid them in future. Anyway, why should one insect be able to eat a poisonous plant and another not able to eat an insect containing the same poison?


davenmidtown profile image

davenmidtown 4 years ago from Sacramento, California

There is a great study of blue jays which were fed Viceroy Butterflies for months and than fed a single monarch butterly... the bird is seen to eat the Monarch and then began to vomit. After that day... the blue jay would eat neither Viceroy nor Monarch. Your cat which is larger than the birds was probably not affected because of volume... The amount of toxin in the butterly compared to the size of the cat. But... consider a bird or another insect eating the Monarch and the amount of toxin per volume goes up. Also... Monarch's are not all the same in terms of toxicity. Some can handle more of the milkweed than others can as such become more toxic. Insects develop niche so that they can survive while others may not. so the niche of the Monarch is to eat the toxic milkweed plant. Almost all lepidoptera have a specific host plant.


Bard of Ely profile image

Bard of Ely 4 years ago from Lisbon, Portugal Author

Yes, good point about the size of my cat! I am well aware that lepidoptera larvae need specific food plants and that is a problem here because there is a shortage of Milkweed which is not endemic. The African Migrant has also colonised the island because two Senna (Cassia) species are grown in parks and gardens.


davenmidtown profile image

davenmidtown 4 years ago from Sacramento, California

Here in California, one of the largest deterrants to insect cultivation are the public use of pesticides and weed abatement chemicals. Home landscaping ornamentals are introducing species of plants where once they were just natives... this entices species such as the Fritillary butterflies too far north where they can not pupate through the winter. ...


Bard of Ely profile image

Bard of Ely 4 years ago from Lisbon, Portugal Author

I am not surprised because I have witnessed the harm herbicides and pesticides do for myself. As soon as Roundup started getting used widely in the UK I noticed less wildlife. It is now being used in Tenerife too, and all over the world from what I can gather. I have seen Nettles killed with it in the UK and as you would know they are the food-plants of several butterflies and moths. I had an argument with a farmer once who said that he used Roundup on his farm and that it didn't kill wildlife. I said well, if it kills Nettles it is killing the food of several caterpillars and if they are on it when you spray it they will all die too.


davenmidtown profile image

davenmidtown 4 years ago from Sacramento, California

Not only do chemicals like Round up Kill wildlife directly, they kill them by removing their food and habitat. The world is knitted together so that everything has a purpose or a use. This is one of the primary reasons behind Colony Collapse. We have shifted the balance to meet our own needs that the result is we have become dependent upon the honey bee, even though there are/were other pollinators available. Here in the United States, we have poisoned most of the pollinators and other insects to the point that we have created a huge collony of honey bees that are weak. It is pretty sad.


Bard of Ely profile image

Bard of Ely 4 years ago from Lisbon, Portugal Author

I agree with you! That was the point I was making with that farmer who was posting/boasting on the BBC Wildlife forums at the time. It both saddens and annoys me what is being done! If I could go back in time to a healthier world I would jump at the chance!


davenmidtown profile image

davenmidtown 4 years ago from Sacramento, California

Was there a healthier time? Even the dinosaurs had issues.... between now and the dinosaurs we had so much war, conflict, the plegue, the famines, DDT, Agent Orange, Nuclear meltdowns, industrial pollution, and even a few minor ice ages... I will have to think about WHEN might be a good time to revisit... hmmmmm


Bard of Ely profile image

Bard of Ely 4 years ago from Lisbon, Portugal Author

Well if I go back just 20, 30 or 40 years there were far more wild flowers, birds, insects, amphibians, reptiles, fish and other wildlife around! Once 'common' species are now rare or even endangered! As a boy I used to see millions of elvers every year climbing weirs in the UK, House Sparrows and Starlings would come down in a small flock if you threw scraps in a garden, Common Lizards were common, but not now!


davenmidtown profile image

davenmidtown 4 years ago from Sacramento, California

That is all true... expansioin and loss of habitat being creating the major impacts, and They took DDT off the market in the US in 1974 and its effects are still being felt today. It is of course used in other parts of the world. You should look up the Dead Zone at the mouth of the Mississippi River.... it is amazing what we do and just keep on doing...


Bard of Ely profile image

Bard of Ely 4 years ago from Lisbon, Portugal Author

I know about DDT and the Dead Zones but what worries me even more is all the plastic going into the oceans every day. It is insane!


davenmidtown profile image

davenmidtown 4 years ago from Sacramento, California

That is crazy too! Plastic has been found in the benzic zone and even been ingested by small organism... which it then kills.... Do we really need all of that crap? At some point we will have to say no.


Bard of Ely profile image

Bard of Ely 4 years ago from Lisbon, Portugal Author

Yes, plastic is now in the food chain and has been found in as much as six pieces of plastic to one of plankton in some parts of the ocean. The Great Pacific Garbage Patch is said to be twice the size of Texas and is mainly made of floating plastic. It is only one of five gyres out there! Beaches in some places have plastic sand now and this has happened in Hawaii. Whales, turtles and seabirds such as albatrosses are swallowing the material and dying. Most species of albatross are now endangered and plastic is a major cause of their deaths.


davenmidtown profile image

davenmidtown 4 years ago from Sacramento, California

One would think we would clean it up... but then its not like got the price tag of Oil...


Bard of Ely profile image

Bard of Ely 4 years ago from Lisbon, Portugal Author

I have heard that it is impossible to clean up due to the sheer volume and the tiny size of most of the plastic out there. There are people working on it though. In the meantime millions of tons of plastic continues to pollute the seas.


davenmidtown profile image

davenmidtown 4 years ago from Sacramento, California

Humanity has always turned the prospect of doomsday into its own economy. At some point, we will have to start paying attention to these kinds of issues... already some coastal towns are having to move and many others are having to consider if they should move or stay. I can't really speak for the rest of the world because I do not know a great deal about cultures outside of the US...but here...this seems to be the home of most pollution, environmental disdain, and yet... we just keep buying new cars, putting in swimming pools, and mining with chemicals that get into our own ground water. I don't want to imagine what would happen if we had a natural disaster on par with Japans....


Bard of Ely profile image

Bard of Ely 4 years ago from Lisbon, Portugal Author

Many places have nuclear reactors so what has happened in Japan could happen elsewhere which is very worrying! Pollution of the environment is worldwide and even where it has not been caused it still gets carried by wind and tides!


davenmidtown profile image

davenmidtown 4 years ago from Sacramento, California

Everything connects one way or another and often times in many, many different ways...


Bard of Ely profile image

Bard of Ely 4 years ago from Lisbon, Portugal Author

Yes, I know! I wish many more people understood this!

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