The earlier papers reported that many monarch caterpillars died after ingesting pollen from the genetically modified corn.

The trial appeared to indicate the pollen of genetically modified Bt corn presented a threat to monarch caterpillars.

Several factors make monarch caterpillars particularly likely to make contact with corn pollen, Losey says.

The host plants used by the monarch caterpillar include:

Biologists first set out to see whether monarch caterpillars would even encounter Bt corn pollen in the wild.

But this summer researchers discovered that large numbers of monarch caterpillars live on milkweed in cornfields.

More important, other scientists report finding this summer that the survival of monarch caterpillars in Bt and normal corn fields is indistinguishable.

These volunteers around the country raised monarch caterpillars on milkweed plants, the insect's food plant, from their area.

Sandhill milkweed defends itself against feeding monarch caterpillars by secreting sticky latex from its leaves.

Since most other animals avoid milkweed, the monarch caterpillars usually have the leaves all to themselves.