An adult deer tick.

An adult deer tick. (Scott Bauer, Agricultural Research Service / May 10, 2012)

It was plain to see that the mild winter and warm spring had flowers and trees blooming ahead of schedule in March and April. Less easy to see are the ticks and other insects that came with them – unless you’re swatting them away.

Tick season got an early start this year by as much as three to four weeks, said Michael Raupp, a professor of entomology at the University of Maryland, College Park. Similarly, the mild winter and early spring heat stirred other insects, like mosquitoes, mites and stink bugs, he said.

That’s because insects are exothermic, drawing their energy from external heat, Raupp said. But it doesn’t necessarily mean all of them will pester people in greater number.

Insects with shorter life cycles, like mosquitoes, spider mites, potato bugs and harlequin bugs will have more time to procreate and grow in number during the longer warm season, he said. But deer ticks’ life cycles are about two years, meaning no immediate impact on their population from the warmth.

The tick population could be boosted, however, by a strong year for oak trees and acorns in 2010, Raupp said. That’s because the acorns meant more food for mice and other rodents, growing their population in 2011. More rodents means more food for ticks.

Public health officials are warning of a worse than normal risk of Lyme disease this year, particularly in the northeast. Maryland health Secretary Joshua Sharfstein recently encouraged Marylanders to take caution, covering themselves well with light-colored clothing as well as DEET insect repellent.

Meanwhile, a gradual warming of Maryland’s climate over the decades has also pushed north pests that were previously active no farther north than the Carolinas. That includes fire ants, relatives of the aphid, and kudzu bugs.

“It looks like the South will rise again here in the North when it comes to these bugs,” Raupp said.