Home | Amphibians | Wild Caught Invertebrates as Reptile and Amphibian Food – Pesticide Concerns – Part 2

Wild Caught Invertebrates as Reptile and Amphibian Food – Pesticide Concerns – Part 2

Please see Part I of this article for a general discussion regarding the collection of insects and other invertebrates and their use in the diets of captive reptiles, amphibians, birds, invertebrates and fishes. Today I’d like to focus on some areas of special concern.

Toxic and Biting/Stinging Invertebrates

Black WidowWhile not involving pesticides per se, for your own safety and that of your collection it is imperative that you learn to identify the toxic or otherwise dangerous invertebrates that you may encounter while collecting. A good field guide (i.e. Audubon, Golden Guide or Peterson series) is indispensable in this regard. Be sure to handle unfamiliar species with plastic tongs.

Please bear in mind that even relatively mild bee venom can cause fatalities in allergic people. And while less than 1% of the world’s 40,000+ species of spiders are considered dangerously venomous to us, a number readily bite both people and animals in self defense. It is best, therefore, to avoid them…the Thin-legged Harvestman or “daddy long-legs”, which are not spiders, are safe to use. Steer clear also of bees, wasps, large ants, stag beetles and others well-equipped to defend themselves.

Bright colors often indicate that an animal is toxic or bad-tasting; ladybugs, fireflies, milkweed bugs and a great many others fall into this category. Unless you are sure of an insect’s identity, the safest course of action is to avoid brightly-colored species.

Native vs. Non-Native Prey Species

In many cases, predators avoid dangerous prey animals that occur naturally within their ranges; this can spare both pet and pet- Milkweed Bugskeeper a good deal of grief!  However, dangerous non-native prey animals may be attacked with abandon if the hunter has no “frame of reference”, so use extra caution in such cases.

I have, for example, housed highly-toxic Marine Toads with Green Anacondas for decades without incident, despite the fact that anacondas consume non-toxic frogs readily. However, Australian monitors and snakes, which have no instinctive or learned toad avoidance behavior, eagerly consume the Marine Toads that have been introduced there, often with fatal results.


Earthworms are one of the most nutritious live foods available. There are, however, situations that warrant precautions.

Earthworms are unique in consuming dirt as they tunnel, and in doing so may concentrate toxins present there. To my knowledge, the only problem that has arisen thus far has involved worms that dwell along golf courses, which are subjected to unusually high degrees of pesticide application. Please see my article Raising Earthworms for details concerning striped skunks and earthworms in NY.

West Nile Control and Related Programs

Avoid collecting invertebrates for 1 week after an area has been sprayed as part of West Nile eradication efforts, and steer clear of farms where pesticides are known to be applied regularly. Avoid also local insects that are considered to be agricultural pests, as they are likely the subject of control measures (this may apply to aphids, caterpillars, Japanese Beetles, etc.).


Despite the precautions that must be taken, invertebrate collecting is a fascinating and thoroughly enjoyable endeavor. Don’t forget to examine your catch closely…several years ago a new species of centipede was uncovered in NYC’s Central Park, on ground trod daily by thousands of people. Like me, you just may wind up keeping some of your discoveries in captivity for their own sake!

Further Reading

For a very interesting account of how toads learn to avoid stinging insects, please see my article Amphibian Learning Abilities.

Please write in with your questions and comments.


Black Widow image referenced from wikipedia and originally posted by Trachemys.

Milkweed Bugs image referenced from wikipedia and originally posted by Greg5030.


  1. avatar

    Very helpfull info! Thanks. I have been wondering about pesticides in the localy caught feeder bugs.

    • avatar

      Hello Jenna, Frank Indiviglio here.

      Thanks for your kind comment. Please write in if you have any concerns about particular inverts…would also enjoy hearing about your experiences using them.

      Good luck and please keep me posted.

      Best regards, Frank Indiviglio.

  2. avatar

    I have used wild grasshoppers caught in area of forest that I was relatively sure was hadn’t been sprayed. I have avoided urban enviroments because of pesticides but also fertilizers and basiclly any other chemicals that may be there, what are your thoughts on this? and maybe a comment on the possibility of introducing parasites.
    Thank you

    • avatar

      Hello Robert, Frank Indiviglio here.

      Thanks for your interest in our blog and for raising these important concerns. I have collected wild caught insects for use as food in urban areas…the vast majority were on the grounds of the Bronx Zoo; pesticide use is restricted there, but insects filter in from the surrounding neighborhood. Insects were collected by hand and trap for herps, birds and, to a lesser extent, mammals (grasshoppers for the Grasshopper Mice…go figure!). While it would seem to make sense that problems would arise, such just never materialized. All animals that die in the collection are subjected to a detailed necropsy, so I’m sure some evidence would have been found had it existed.

      Fertilizers might be a concern in high use situations, such as farm ponds (frogs in farm ponds are being affected, but likely directly, through water absorption, rather than via diet) or with earthworms in golf courses. I always play it safe and avoid such areas, also heavily targeted insects, such as free-living roaches.

      I am aware of one example of potential secondary poisoning related to an urban environment. In the past, zoo staffers trapped pigeons to control their numbers in outdoor bird exhibits. These were fed to a number of crocodilian species. Testing later showed that the pigeons’ lead levels were off the chart – apparently because they consume large quantities of gravel from city streets, as a digestive aid. While elevated lead levels were not detected in the crocs, the practice was stopped as the vets were certain that there was potential (however, some animals in the croc collection that had dined on pigeons for years, including 2 Cuban crocs, lived in excess of 50 years and reproduced). Marsh Crocodiles, on the other hand, were poisoned by zinc that leached out of coins (tossed into their open mouths by unthinking visitors) that they had swallowed.

      Parasite transmission via invertebrates is largely limited to parasites that require 2 hosts in order to complete their life cycle. The most common intermediate hosts are crayfish and snails, although terrestrial inverts are also involved (especially earthworms). However, most such parasites are very specific as regards both hosts, and also must be present in the right stage of their life cycle if they are to infect the second host. At the zoo, we used wild caught snails and crayfish as part of the weekly diet of many turtles and some other herps without incident. Some zoos do, however, treat these food items in order to kill parasites before using them as food for the animal collection.

      So there are some risks, but, in my experience, these can be easily managed. If you keep animals that will accept dead or tong-fed food items, Canned Invertebrates, which are farm raised and cooked, are a safe alternative.

      Good luck and please keep me posted on your thoughts and experiences.

  3. avatar

    Hi Frank,
    I know this is an older blog but very relevant today.I live right next to a wood and being involved with moth trapping and many other things with the wood group, I was wondering what you thought of netting insects in the woods, we do have an extremely large badger population in the woods,and a few rats.
    Knowing the diseases and TB that badgers carry.
    Do you think this would make it unsuitable for reptile feeding of caught insects,moths etc.

    There is also a handy tip for your blog readers who do wish to capture insects, if you wrap damp woven material such as sacking or calico around a tree over night , you can remove it in the morning and hey presto lots of insects will be nestling on or under it.
    Also if you haven’t got a light trap for moths you can warm brown sugar in a saucepan with a bit of honey mix it together to a gooey paste, then smear it on your tree or even your fence and you can collect the feeding moths also after an hour or so there should be quite a few.
    Collecting moths is best done after a light shower, which i am sure you will know, but your readers may not.

    • avatar

      Hi Bella,

      Nice to hear from you again; thanks very much for the useful tips. I’ve been meaning to write a follow-up article. I enjoy using bait for moths as you describe (have luck with molasses as well), and very effective and interesting. Thanks for reminding me about the tree trunk trap; I’ve not thought of that in a long time. Looking forward to spring!

      I’ve never had any problems using wild caught insects collected here in NY, and we’ve not seen any evidence of such via autopsies done a the Bronx Zoo. I would avoid collecting near agricultural areas where pesticides are used, or after large scale spraying of mosquitoes, etc. (West Nile control efforts here). TB from badgers would not seem to be a concern for herps, but I’ve not researched that specifically.

      European Badgers are not often seen here in US zoos; one under my care many years ago lived into it’s mid 30’s, but I’ve not sen any since. Interesting that they are common there…where are you located? Have red fox and hedgehogs also adjusted to human presence, as I often read? Best, Frank

  4. avatar

    Hi Frank,
    Sorry for my late reply, been, nursing the new spiny tail.S. Ponsettia, which is a little difficult as they are very flighty and nervous.

    I am in Hastings, East Sussex in the United Kingdom.
    We have red foxes, but I am lucky enough to have one with a little family in a lair 2 doors away, the Vixen is large and so beautiful, I often watch her and the kits playing on the garden lawn in the garden at the back of the neighbours house, we have an alley at the back which they always walk along.
    Since I have been in the house there isn’t one year she has not had a litter of at least 4 kits, and I have been her 6 years, tells a story doesn’t it .

    We did have one year when there when only 2 survived, but that was the year when, the vole and water rats and most of the smaller mammals failed due to the weather.
    The baiting pipes I put out had virtually no scats in them that year either not good for all the wildlife.
    The resident owl had no owlets that year either.

    Hedehogs are very common place here but most are hibernating here as it is still to cold for them.
    The common grey foxes are every where we have one competeting for the red foxs area, they scream at each other, the badgers likewise sounds like a real battle sometimes but there more warnings, they naturally avoid out right fighting , but,, it does get close to it sometimes.
    We have big male brocks that walk past you in the night I often go badger and fox watching in the spring and summer.

    If your ever over this way let me know, you would be most welcome to come along.

    With reguards to insects, i would never collect from agriculture areas.
    Maybe I will see if i can find some research if any about the effects of badger T>B on reptiles if any exsists.
    Spring is certainly a glorious time, but I love the winter as well, there are still many bugs and thing s to see in the woods and countryside around here, you just have to look harder, I love all the diffent Fungi that spring up in the damp conditions.I could go on for hours, but I wont on here lol.
    Oh I have used Mollases but its very expensive here, as honey is getting due to the disease in the honey bees very sad so many dying.
    Thank you Frank its always a pleasure talking to you.

    • avatar

      Hy Bella,

      So interesting to hear about the foxes, thanks. Red fox are adjusting to people here a bit, but only in suburbs, not in the city. Gray foxes very scarce, and are almost never found where reds are present; I’ve never run across other accounts of their facing off like that, thanks. I do lots here in winter as well; am out every week with 5 year old nephew, we collect mantis egg cases, moth pupae etc and hatch; he’s fascinated by fungi as well. Last Feb during a warm spell even found a Common Snapping Turtle basking in shallow water. European Hedgehogs not seen in zoos here very often; the smaller Africans were popular in the pet trade, but I believe imports restricted now. Thanks, I’ve never been to the UK and will certainly be in touch if I can take a trip. Honeybees in same situation here, commercial beekeepers now travel around the country with hives, pollinating crops, but die-offs common. I was chased by invasive African honey bees in Venezuela, they are established in the SE USA, but not raised commercially. Best, Frank

  5. avatar

    Hello again frank,
    Great to hear about your nephew start then young is what I say,.
    I had a computer crash and lost many of my photos such a shame I had some beaty’s of fungi in the woods and countryside, that will teach me to put all on discs from now on.
    Actually with regaurds to Hedgehogs this news is very sad, there is a huge decline in Hedgehogs ,thought you might like the link, also a link you may have seen already but it’s all about the Crevice lizard, I have now and the Polotician in America it was named after, and some lovely line drawings of the crevice.

    Sad to hear it’s the same with Bees over there.
    Wow Venezuela, how wonderful shame about the bees chasing you.
    Never been to the UK Frank, I’m really suprised, we have some amazing wildlife parks here amongst other things.
    You could say the same about me as well i have never been to America.
    Crikey it is 2.40am better get some sleep.
    Take care speak soon,

    • avatar

      Thanks for the links; I’m interested to see what’s going on with the hedgehogs; we’ve seen declines in striped skunks in some places here, perhaps linked to pesticides (in spring, they gorge on earthworms at golf courses); I’ve heard and read fantastic things about your wildlife arks; Gerard Durrell was a major influence on me, and the work of his wild;life trust continues to inspire. In fact, he factored into my landing my first zoo job (please see this article); as a child, I was captivated by the book To the Zoo in a Plastic Box, the story of 2 brothers who collected insects for the London Zoo; I still re-read it from time to time.

      Bee decline was linked to mites, pesticides, an untreatable disease and other factors; not sure if there is a definitive answer yet,.

      Here’s one on newly discovered fishes, some also named after politicians.

      I worked with anacondas in Venezuela..tag/release; tagged over 500 (with others!~) plus orinoco crocs, lots of electric eels, stingrays, some jaguar, not to mention a lagre criminal element in some places, but African honeybees were the worst threat!

      I was the same way with photos until I started watching my nephew, now I save all (and use his photo in book dedications!); here he is at 4, bagging a Dekay’s (Brown) Snake.

      Let me know if you ever plan to visit, Best, Frank

  6. avatar

    Hi Frank,
    We only have Skunks in Zoos etc here not in the wild.
    There do now seem to be imported into this country now as Pets, but unfortunately most of those have a procedure to stop them being able to release the awful smelling liquid when threatend.
    I actually wholly disagree with this and dont like the idea of any reptile or animal be doctered in this way, it disturbs me greatly..

    Your nephew is a real cutie ,I as well found hours of pleasure on persuing wildlife of all sorts when young.
    Woodlice were my first venture until they were found in a shoe box in my room amoungst leaves, wood and soil from the woods, (frowned upon and prohibited) now of course to remove anything from woods over here ). daily I would tip water onto the soil and add more woodland, lol,.
    My adoptive mother hated insects in fact any wildlife, but when I was old enough I bought any books I could and later, I think I must have bought most of the Gerald Durrel books and like you, he was my main inspiration to learn more, although the book you read, I have never seen.
    Unfortunately all my books and observation of those early days were thrown out, but we wont go into that.

    I would love to visit ,unfortunately I have a disabilitating illness now (M.E ), which does not allow me to travel far anymore.
    I have a daughter in Australia, who lived in Tasmania to start but alas, I could never visit to far for me.
    I did how ever manage to get to Africa just as my illness started, plenty of Skinks and Geckos,Lizards etc, if fact the hotel staff would tread on them as they would be over run with them this was about 13 years ago.
    In fact there were hertoligist walking about the hotel grounds then, although, I didn’t get the chance to speak to them.
    It was fascinating watching the resident vultures being fed outside the kitchens ,where the kitchen staff would throw the scraps out for them, such vulgar eaters, no manners at all, lol.
    the Rhesus monkeys I spent hours watching, oh for that life again.
    Still there is lots in the Uk and Tunisia which I like to visit about the furthest I can go now.
    Thank you for the interesting link to Skinks, they have always intrigued me.
    Did the evolution proccess lead to a snake like creature having legs and thus being called Skinks.
    If this was the case what name was given to the snake like creature before it grew legs.
    Re your question about information, if you could email me any Pink Tongue Skink information/ research I would be very grateful.
    I have a Pink Tongue rescue and would like to put some more detailed information about them on my rescue page.
    Thank you Frank
    would be very grateful.
    N.B When I try to follow you on RSS feed this come up, which I dont understand ? This XML file does not appear to have any style information associated with it. The document tree is shown below.

    • avatar

      Hi Bella,

      Thanks for your note…yes, plenty to see everywhere, new centipede species was found in NYC’s Central park in recent years, appx 2,000 insect species resident, nearly 300 species of birds sighted on grounds og Bx Zoo…I’m sure you’re getting the most out of where you are and go.

      The current theory is that snakes evolved after lizards…monitors seem to be the most highly evolved of the lizards, and there are many similarities in their senses (tongue/Jacobsen’s organ) etc to snakes. The body form and reduced legs of some skinks seems to be an adaptation to burrowing below leaf litter and soil, esp. noticeable in the “sand fish”; we see this also in other lizard groups (glass lizards), and many salamanders. great stuff, new info surfacing all the time.

      I’ll get back to you soon on the pink tongue,

      Take care, Frank

  7. avatar

    Hi Frank,
    Thank you will look forward to hearing from you re the pink tongue.

    • avatar

      Hi Bella,

      Pink tongued skinks can be kept in a similar manner to the more common blue tongues; Please see this 2 Part article for details.

      They prefer slightly moister conditions than Blue tongues – spraying 2x/day and providing a lg water bowl is fine in most homes. UVB is important, UVA may be beneficial. Field reports indicate that snails and slugs form much of the diet, at least when available. Captives will take slugs, edible snails (human-grade) and perhaps the canned snails now marketed as herp food, but they are not specialists. They can be fed a wide variety of insects, commercial and w/c. Roaches are preferable to crickets as a staple; some super mealworms ok but limit amount. A pink mouse can be given if desired each 4-6 weeks. A mixed salad of kale, collards, romaine, dandelion, etc., with a small amount of fruit, should be offered; many refuse greens, mixing in some live food may encourage them to try. Powder most meals with calciumD3 and use vit/min supplement 2-3x weekly.

      Temps should range from appx. 75-82 F, with a 90F basking site. Provide hide boxes/caves; most tame down but “stiff” smooth body renders them easy to drop; they have powerful jaws and will bite if stressed.

      Pl let me know if you need anything further, enjoy, Frank

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About Frank Indiviglio

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Being born with a deep interest in animals might seem unfortunate for a native Bronxite , but my family encouraged my interest and the menagerie that sprung from it. Jobs with pet stores and importers had me caring for a fantastic assortment of reptiles and amphibians. After a detour as a lawyer, I was hired as a Bronx Zoo animal keeper and was soon caring for gharials, goliath frogs, king cobras and everything in-between. Research has taken me in pursuit of anacondas, Orinoco crocodiles and other animals in locales ranging from Venezuela’s llanos to Tortuguero’s beaches. Now, after 20+ years with the Bronx Zoo, I am a consultant for several zoos and museums. I have spent time in Japan, and often exchange ideas with zoologists there. I have written books on salamanders, geckos and other “herps”, discussed reptile-keeping on television and presented papers at conferences. A Master’s Degree in biology has led to teaching opportunities. My work puts me in contact with thousands of hobbyists keeping an array of pets. Without fail, I have learned much from them and hope, dear readers, that you will be generous in sharing your thoughts on this blog and web site. For a complete biography of my experience click here.
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