Caterpillars and pet flea/tick medication

Deadly to butterfly caterpillars, flea/tick medication is an essential in our home.  The part of flea/tick medication that often doesn’t register in our brains, is that it is a pesticide/insecticide.  That’s why it kills fleas and ticks.  When we raise caterpillars and protect our pets with systemic medication, we simply use caution.  Pets on medication and butterflies can co-exist.

Our daughter’s dogs and cats have a terrible time with ticks. We live in the country and after one of his treks in the yard, we found over 100 young ticks in our dog’s fur. He had found a patch of young ones while playing outdoors, playing with the cats. Yes, we do use tick medication on Grim. Yes, Grim lives in our home.

Although it is called ‘medication’, flea and tick medication is actually an insecticide/pesticide. It does not harm the furry animal or us, but it is deadly to pests that attach to them. Some are organic and some are not. Both are deadly to ticks and caterpillars.

Systemic flea/tick medication, both oral and topical, enters into the pet’s body.  As we pet our dogs and cats, the medication/pesticide transfers to our hands through body oil and pet dander.

Tick medications work in different ways, depending on the active ingredient. Some affect mouth-parts, some affect nervous systems, some act in other ways.

Flea/Tick medication active ingredients:
Different active ingredients are used in different flea/tick medications. Checking the active ingredient of any flea/tick pesticide will reveal which active ingredient is in that particular pesticide. Pyrethrins are organic, made from certain species of chrysanthemum plants. It affects the nervous system of insects. It causes a repeated firing of nerves. Pyrethroids are synthetic, but work in the same manner as Pyrethrins. Arylheterocycles also causes paralysis by blocking the passage of chlorine through cells in the insect’s nervous system. Undecyclenic acid and dioctyl sodium sulfosuccinate softens the waxy coating of fleas and other target pests, finally affecting organs and causing death. Amitrax is a formamidines also inhibit nerves. Selamectin and Nitenpyram also block nerve signals from being transmitted. Dinotefuran blocks nerve signals and doesn’t not have to be ingested for it to affect an insect. Spinosad affects the nervous system, causing muscle spasms, paralysis, and death of the insect. Citrus extracts affect the insect’s nerves. Borax inhibits development of caterpillars. Imidacloprid blocks nerve receptors. The insect’s nerves are not able to send a normal signal. It tends to cause a degree of paralysis. The ones that cause paralysis often causes paralysis of the caterpillar’s mouth. It can’t eat as much as normal and simply doesn’t thrive and eventually dies from starvation. It doesn’t grow as quickly, becomes a bit squishy, and the death is often similar to Bt except that the caterpillars can often eat a little (but not as much as normal) each day. Insect growth regulators and inhibitors prevent the insect from maturing. An insect’s juvenile growth hormone keeps it from maturing into an adult. Arylheterocycles keep the growth hormone at a high level, preventing successful pupation.


How can pesticides (such as those on our pets) affect one species and not another? There are several ways. Sometimes we touch the food or caterpillars of one species more than we touch the other’s food. It can come from our hands and transfer to the food.

Why would only some species or some caterpillars in one species be affected?
• When we touch our animals, their cuticle oils come off on our hands. When we touch a caterpillar or its food, the poisons are transferred to their food or cuticle. If we touch only part of a leaf, the caterpillars that eat that part will be affected. Those eating other parts of the leaf may not be affected.
• If we are feeding several species, the one we feed first is more apt to be affected. By the time we feed other species, we may have washed off or worn off most of the pesticide.
• We are more apt to handle one species more than another. The one we handle the most has more growth regulator exposure.
• Some species are most likely more vulnerable to growth regulator than others.

We recommend washing hands THOROUGHLY or wearing disposable gloves when touching food or caterpillars. It should greatly improve your success rate.

(Side note: Grim was named after DanTDM’s dog. DanTDM is on youtube playing Minecraft, a favorite of one of our grandsons.)