Purple Martins are very adaptable creatures. If they hadn't been able to make the shift from
nesting in trees to human prepared nest sites, they would not be nearly as numerous. Because
we have attracted them, we have a responsibility to provide the best care that we can for them.
We build housing that protects them from outside factors like weather, predators and nest-site
competitors. We even supply calcium-rich eggshells or grit to supplement their diet. One area
that is under debate is the prevention of pest infestation. Mites, lice, ants and blowflies can
make the birds miserable at best and even manage to kill hatchlings. By having the birds in
such close proximity to each other causes the pest problem to explode. In effect, we have
caused the problem, so we must solve it. The most effective solution is the application of 5%
Sevin Dust. Careful dusting at the onset of pest infestation eliminates them. A one-time
application solves the problem for the breeding season. Data from the EPA clearly shows that
this pesticide is safe. Certainly, the risk of chick mortality is greater from pests than from Sevin.
Landlords who use pesticides are concerned as to the legalities of their usage. Technically, it
is still illegal to use any chemical treatment on a wild bird nest. Realistically, prosecution would
not be likely as we are aiding the birds by our actions. The key is making sure that the smallest
amount necessary is used in order to minimize the risk. We do not recommend the use of DE
(diatomaceous earth) because it is a known carcinogen and when the young birds are testing
their new wings it gets stirred up in the air and goes into the bird's lungs.
The EPA's own data from their Integrated Risk Information System (IRIS) shows just how safe
Carbaryl (Sevin) really is. In order for Carbaryl to even affect a human, 5.48 mg/day (120,000
times higher than workers in the manufacturing plant get exposed to) would have to be
consumed over a long period of time. It has a moderate to low mammalian toxicity. It is not
considered to be an oncegen (tending to cause tumors). It is a weak mutagen (tending to
cause mutations) and available data indicates that it has only low teratogenic potential (causes
extreme malformations or monstrosities). Carbaryl is not expected to contaminate groundwater.
While it is extremely toxic to aquatic invertebrates and honeybees, it has only low toxicity to
birds (Carbaryl was designed to control infestations in the poultry industry). An important
aspect of Carbaryl is how quickly it breaks down and is rendered harmless. Its insecticidal
properties are lost after 3-10 days (moisture breaks it down to a non-toxic form). Most animals,
including humans, readily break down carbaryl and rapidly excrete 75% of it in 24 hours. Data
suggests that there is low to very low toxicity to birds.
Most landlords are only using a teaspoon of 5% Sevin Dust applied on the nest at the first
sign of nest mites. Tap the nesting material to allow the Sevin Dust to fall to the bottom of the
nest. A single application usually solves the infestation within 3 days. Since moisture in the air
will render Sevin Dust inert in a few days after being opened, only purchase the smallest
amount necessary for a single application to all nesting compartments.
The presence of pests on Purple Martins and in their nests is a serious health risk. A quick and
serious solution must be found for these birds that need our help to survive. 5% Sevin Dust
seems to be the most effective and low risk method to solve this problem. Just as laws make it
technically illegal to make nest replacements, return fall out hatchlings to their nests and, even
to use Sevin, a sense of reason and common sense should allow humans to do our best to
properly care for this exceptional bird. As long as a minimum dose is effectively applied, it
surely is in the best interest of our Purple Martins to keep them healthy and thriving as our only
semi-domesticated bird species.
CONTROLLING PEST INFESTATIONS