In article , Stephen
Henning wrote:
We getting lots of Green June Bug swarming over our lawn this year. It
is their mating time. They aren't eathing anything, just making lots of
grubs. Lots and lots of grubs. Is their any non toxic control for the
grubs. We have a shallow well and can't use any thing like diazanon.
A two-prong attack will be a permanent control:
Milky spore (Bacillus popillae) permanently limits the activity of grubs
(& if population can be kept always to one to three grubs per square foot,
the lawn & garden will be perfectly healthy). Milky spore can thrive &
remain viable in the soil for a decade or permanently once the population
is infected, because each grub that dies releases more milky spore
bacteria into the soil for the next batch of grubs to eat. It has the
bonus that it does not effect butterfly larvae (as B. theringiensis
would).
Steinernema nematodes are also a permanent control which takes two years;
by the third year the june beetles will be incapable of a major explosion,
the population pretty much permanently infected with the nematodes & never
able to recover in any big way. Application of nematodes can be done once
or multiple times from about mid-July to to August or September, & that
may be enough to last for decades, though sometimes it should be done a
second year.
Here's an excellent general introduction to understanding biolgoical control:
http://edis.ifas.ufl.edu/BODY_IN081
Microbial control method works the first year of application so it takes
patient avoidance of chemical controls which will retard or eradicate the
effectiveness of the biological control. Since you've noticed the adult
beetle population BEFORE you've seen the the damage, you already have a
one or two year head-start on the grub population. Most people find out
about them after lawn & plant damage is obvious, & that rarely occurs in
one year, so for you the nematodes & milky spore will probably take down
the population before they've done much damage. But one of the best
immediate controls people somehow overlook, or people with mulch-mowers
may never even think of:
Adult June beetles often appear en masse & mate as a large population most
of them in the same week. While they are active over the surface of the
lawn, a really good lawn mower set at minimum height, with clipping bag
attached, can literally vaccuum up the adults, & the clippings
double-bagged for municiple pick-up, or fumigated with a vapona strip in
each bag for a week or two before composting, or the clippings burned.
Also available as an effective biological control are parastic wasps
(Tiphia intermedia), which parasitize beetle grubs as their first choice.
Some of the finer independent nurseries will seasonally sell parasitic
wasps in early autumn, or they can be obtained from any number of mail
order sources.
Pelecinus polyturator is a spectacularly effective june beetle grub
hunter, but I don't think obtainable commercially. It's a two-inch big
jet-black flying insect, the female having a long spooky ovipositor often
mistaken for a stinger of some kind of super-wasp & totally scary to see,
but harmless to people & beneficial to the lawn & garden. It won't exist
where chemical insecticides have been used, but will annually become an
increasingly important control in a balanced organic garden.
Many regular wasps will also hunt grubs so wasps generally should be
encouraged & left unmolested in the garden, the majority of species
being suprisingly docile & of no threat unless one bangs right into a
nest. Also, ants feed on June beetle eggs before they even hatch, so if
you see a line of ants marching around in the lawn, don't freak out & kill
them, ants are your friends.
Starlings are also super-qualified white grub controls, so if the
starlings have ever annoyed the bejabbers out of you as garbage-birds,
think of them in the future as the white grub police. Robins also do a
pretty darned good job of yanking white grubs out of the lawn. Birds in
general should be encouraged.
Moles & skunks are the less often welcomed white grub predators. The
Olympic mole can be almost undetectible & so a welcome garden inhabitant,
but the Townsend mole makes dozens of mole-hills & usually not tolerated
because the hills are unsightly though not actually harmful. The skunk
arrives by night & leaves a series of cone-shaped holes throughout the
lawn, & will continue this activity for as long as there are grubs to be
found.
-paghat the ratgirl
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