Bug zppers, mosquito control, malaria, flocking behavior

<x-flowed>First, on bug zappers:

ENTOMOLOGICAL NEWS [107(2): 77-82]. The following is their abstract:

"Our survey of insects electrocuted during routine use of electric
insect traps revealed only 31 biting flies, a minute proportion (0.22%)
of the 13,789 total insects counted. In contrast, species from 12
orders and more than 104 nontarget insect families, including 1,868
predators and parasites (13.5%) and 6,670 nonbiting aquatic insects
(48.4%) were destroyed. The heavy toll on nontarget insects and the
near absence of biting flies in catches suggests that electric insect
traps are worthless for biting fly reduction - and probably are
counterproductive - to homeowners and other consumers."

Other consumers would of course include insectivorous birds and bats.

Two cases of malaria have been confirmed in northern Virginia. Both were
teenagers. Neither had traveled out of the country.
The pesticide trucks were out in full force immediately.

Does anyone know if this widescale spraying actually knocks back the
mosquito population to such an extent that the risk of
exposure is significantly reduced? Or is this more like the prescription
of antibiotics for the common cold?

I drove the perimeter of what was a huge crow roost the other evening.
In fact, I drove it twice - not an easy thing to do in rush hour traffic
in Montgomery County Maryland. I saw no crows at the roost or in any of
the staging areas where the crows accumulated prior to flying west into
the roost area. In total, I saw four crows, all on the wing, and all
flying in random directions, loosely circling, over what was a major
staging area. It looked like frustrated flocking behavior, and it was
heart breaking.

The good news is that the Carolina Wren that I thought had gone missing
seems to have returned today. Montgomery County has the highest
incidence of WNV in the state, and the area where I live has the highest
incidence in the county. We have seen virtually no birds in weeks. The
cardinals, catbirds, chickadees, sparrows, doves - all absent.

I would guess that the birds in drought-stricken areas are having a
tough time generally, and may be more vulnerable due to drought-related
stress, but of course, w/out data to see if the impacts are greater in
some areas than others, we can't know that.

A fair number of biologists who admittedly know far more than do I are
willing to say that this isn't going to wipe out some wild bird
populations. While of course the virus itself is unlikely to take all
individuals in a population, the very low density that is likely to
result will make it difficult for hard-hit populations to rebound.

Ellen Paul

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Received on Sun Sep 15 00:31:42 2002