In fact the [monarch] butterfly population, which normally numbers in the 10s of millions, may be down by as much as 50 percent this year, [Texas A&M researcher Dr. Craig] Wilson said. That's because of a cold and harsh winter in Mexico -- butterflies are especially vulnerable to the cold after getting wet -- as well as illegal logging near their nesting grounds.
Unfortunately the butterflies may not find much hospitality on the Texas leg of their northward trek.
Butterflies lay their eggs on milkweed, and the plant has been slow to grow this year in Texas because of the near-record cold. Wilson said the milkweed in his butterfly garden on A&M's campus has yet to emerge.
Monarchs suffered a harsh one-two punch this past winter. A severe storm in late January and early February brought heavy rains and mudslides to to the monarch's overwintering grounds in Mexico. These storms and their effects, which have been extensively documented on the monarchwatch.com blog, utterly decimated the already smaller-than-normal hibernating population. A colder-than-normal winter here in Texas, meanwhile, killed the local overwintering monarch population (there is generally a percentage of monarchs that do not complete the entire journey to Mexico) and wiped out the host milkweed plants. That, in turn, means that there are very few plants for whatever migrating population that remains to lay eggs upon as they pass through Texas on their way up north. It's a bad situation all around.
However, as was noted in the comments of Eric's blog, insect populations can be remarkably resilient, so it's a bit early worry about the monarch being put on the endangered species list. Secondly, now that the spring planting season is underway we can do our part to help: start planting that milkweed, folks!