Wild Caught Invertebrates as Reptile and Amphibian Food – Pesticide Concerns – Part 2
Hello, Frank Indiviglio here. 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
While 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-
keeper 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
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.).
Enjoy
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.
Thanks, until next time,
Frank Indiviglio
Black Widow image referenced from wikipedia and originally posted by Trachemys.
Milkweed Bugs image referenced from wikipedia and originally posted by Greg5030.
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about 2 years ago
Very helpfull info! Thanks. I have been wondering about pesticides in the localy caught feeder bugs.
about 2 years ago
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.
about 2 years ago
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
about 2 years ago
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.