Using Milk as a Natural, Homemade Pesticide

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PHOTO: FOTOLIA/KUBAIS
Milk can be used as a natural pesticide.MM

Spraying your plants with milk
won’t drive bugs away from your garden, but the dairy
product can be used to culture Bacillus thuriugiensis
Berliner, a well-known bacterial pesticide sold under such
brand names as Dipel, Thuricide and Biotrol. The agent is
quite effective in controlling — among a number of
insect problems — infestations of loopers, which are those
pesky little worms (they’re actually moth larvae) that
attack broccoli, cabbage, cauliflower and other members of
the cole family. Once eaten, the bacteria paralyze the
larvae’s intestinal tracts and bring about their death in
two to four days.
Before you spray your garden with
thuringiensis, though, be aware that this
bacterial-warfare weapon is fatal to the caterpillars of
all Lepidoptera (an order of insects that includes many
lovely, and relatively harmless, moths and butterflies) . .
. so please don’t employ the remedy in cases where simply
handpicking the loopers off your plants will do the job.
(That rule, of course, applies to the use of any pesticide,
natural or otherwise!)

Using Milk as a Pesticide

If the little green caterpillars get completely
out of control, you can go to the store and buy some
commercially prepared Bacillus thuringiensis (BT) and
use the product in conjunction with the pests themselves
to brew your own supply from that point on! The basic
procedure for doing so was mologist at Louisiana State
University’s Cooperative Extension Service in Baton Rouge.
Dr. Pollet decided that because milk is a good medium for
bacterial culture (a fact that not only causes the
liquid — especially when unrefrigerated — to spoil,
but allows us to harvest such by-products as cheese,
yogurt, and kefir), and since Dipel, Thuricide and Biotrol
are all bacterial pesticides, it should be possible to
use milk to extend the bacteria’s useful lives.

According
to a report on Dr. Pollet’s work, the process goes like
this: The pesticide is sprayed on the plants, where it’s
eaten by the loopers. Then the tiny parasites develop
inside the caterpillars’ bodies and kill their hosts. When
the infected larvae are gathered before the bacteria in
them die, and are blended into milk (an effective culture
for the microorganisms), the bacteria strain will stay
alive and can be used again to kill other loopers.

Experimenting With Natural Pesticides

After reading this report, I decided to conduct my own experiment: I wanted to
see for myself whether the system would work. (Besides, I
always jump at any chance to save money, and commercial
bacterial pesticides are expensive!)

All the project
involved was gathering a palm full of infected loopers from a
section of my cabbage patch that had been treated with some
store-bought BT . . . mashing and blending them into one
pint of warm milk (I thought a lukewarm environment would
promote bacterial reproduction . . . then letting the looper
or milk mixture stand for three day, sure the caterpillars
you start with are still fresh. Once the larvae are dried
up chances are the bacilli will no longer be active.) Next,
I strained the brew through cheesecloth, diluted it with
water to make a gallon of liquid sprayed the concoction on
some looper-infested broccoli plants.

Two days later, it
was evident that the larvae were no longer eating. By the
next day they were becoming discolored, and soon thereafter
they were very dead. My experiment was a success!

Putting Homemade Pesticides to Use

Having once-used loopers
infected with bacteria from a commercial source to make a
new batch of pesticide, I wondered whether I could continue
the chain by using pests that had been sprayed with my home brew (much as a starter from each batch of yogurt can
be used to make additional yogurt). So I gathered a dozen
loopers from the broccoli, treated with my pesticidal milk
shake processed them in the same manner sprayed a second
infested patch. This third generation mixture proved to be
just as effective as the first and second applications had
been.

And just how many times could the process be repeated?
Well, I really know, but it’s reasonable to expect that as
long as the
Bacillus thurangiensis Berliner can be kept alive — and
milk to provide a ready means of doing that — the
bacteria will live to serve you again and again.