What an interesting group of creatures are the beetles! Many beetle (order Coleoptera) species find their homes and make their living in the varied habitats of Torrey Pines State Natural Reserve – some at the beach, some in the marshlands, some in the sands or plants of the Coastal Sage Scrub, others in the Torrey Pine woodlands.
On the sandy upland trails, hikers frequently encounter the Armored Stink Beetle. If its movement is suddenly blocked, as by a shoe, it will usually lower its head and raise its abdomen and may release a bit of smelly fluid from the tip of its abdomen as a defensive tactic. The Stink Beetle is one of many insects that live on decaying plant matter, and help to return nutrients to the soil to complete the cycle of life.
On the beach, the Kelp Beetle feeds on the seaweed that washes up, and the beautiful Pictured Rove Beetle comes out at night to feed on other insects that make their living in the kelp. Down in the marshlands there lives the amazing Sexton Beetle. This little insect, together with its mate, will actually bury a mouse or other small animal, and guard this treasure while their young are growing up! Imagine how much energy that would take!!
Still other beetles help to decompose the dead wood of fallen trees, or prey on other insects that can be harmful to the trees. In these ways – by recycling plant and animal material, by preying on each other, and by being prey for larger insects, birds and animals, these creatures are an important and vital part of the cycle of life.
The beetle that has attracted the most attention at the Reserve is the bark beetle. A link to more beetle examples is at the bottom of this page; go see and read about a selection of these fascinating and important inhabitants of our world.
Five-spined Engraver Beetle, aka The Bark Beetle
Many park visitors ask about the “fire-destroyed” trees they see in Parry Grove or from the Guy Fleming Trail. These trees were not burned, they were killed by the bark beetle (Ips paraconfusus), also called the five-spined engraver beetle. During the 1980’s, a combination of drought years and bark beetle infestation killed more than 650 Torrey pine trees. Because Torrey Pines is a Reserve, the policy is to let nature take its course, so the remains of these trees can still be seen in the groves where they died.
The bark beetle is a small insect that bores into the bark of a pine tree and creates egg chambers in the cambium, the living tissue of the tree. The larvae feed on the cambium, pupate and emerge as adults to repeat the cycle. Sometimes 3-4 lifecycles occur in one year. Usually the trees can protect themselves against this invasion by pushing out the insects with sap. But during drought or other times of stress, the trees’ defenses are low, and the insects can do enough damage to kill. Observe some of the fallen trees on the sides of Guy Fleming or Razor Point trails. You will see the “engraved” pathways the beetles have made in the wood.
At the time of the infestation in the 1980’s, there was much debate about whether and how the staff might intervene to save trees. Some might think it obvious that some intervention should occur to save the rare Torrey pine, but the Reserve is dedicated to preserving and enhancing natural processes, and usually maintains a “hands-off” approach. However, because of the severity of the problem, it was decided to try trapping the beetles. Traps made of cones bated with beetle pheromones (chemicals the insects use to attract mates) were placed in the groves. This was considered the least disruptive way to save the trees. Fortunately, the rains returned and this helped the trees to develop enough sap pressure to expel the beetles. The traps were removed in the mid-1990’s, and the groves grew more healthy with seedlings and young trees appearing to replace those which were destroyed. In 2001 the trees became stressed again, and traps have once more been placed at various positions in the Reserve to catch and monitor these beetles.