I really enjoy the days when I have an opportunity to go over insect images I’ve taken, but haven’t yet had the chance to identify. This small (approx 7-8mm), metallic beetle is a leaf beetle in the family Chrysomelidae. It’s a Long-horned Leaf Beetle (Plateumaris germari). They are associated with aquatic habitats and this specimen was found near a wetland habitat on San Juan Island, WA., May 12, 2015. Yes. I’m slow at getting around to sorting things, but was happy to share this one today.
I received this photo yesterday of a very cool Cerambycid (Long-horned) beetle from Chase S. on Canoe Island, WA. This is a Whitespotted Sawyer beetle (Monochamus scutellatus). These beetles are found in forested areas across the continent. The first time I saw one on San Juan Island, I almost mistook it for a giant black spider. Its long antennae give it the appearance of having eight legs, like an arachnid.
The larvae (known as sawyers) of Monochamus beetles develop in the wood of fire-scorched, diseased or injured, dying pine, Douglas fir, true firs, and spruce trees. The adult beetles lay eggs in slits in tree bark. Larvae (grubs) develop through several instars before pupating. The younger larvae feed on wood beneath the bark and filling the void with long, fibrous borings, then move into the wood, forming holes that will become almost perfectly round as the tunnel grows deeper. The tunnels can eventually reach the heartwood of the tree.
Prior to pupation, the larvae will pack the deep gallery with grass, leaving a space at the end for the pupal cell or chamber. Adults will emerge by gnawing through the cell and a thin layer of wood and bark to the surface. Telltale signs of boring damage is the accumulation of debris along infested logs. As they can attack and damage recently felled trees, they are considered a pest in logging areas. According to Furniss and Caroline’s 1977 Department of Agriculture Forest Service Publication No. 1339, utilization of preventative methods that avoid leaving logs exposed during the beetles’ egg laying period ( July-September ) is the best approach.
Furniss, R. L. (Robert Livingston)., Carolin, V. M. (Valentine M.)., United States. Forest Service. (1977). Western forest insects. [Washington]: Dept. of Agriculture, Forest Service : for sale by the Supt. of Docs., U.S. Govt. Print. Off..
Haggard, P. and Haggard, J. (2006). Insects of the Pacific Northwest. Timber Press Field Guide.
Peterson, M.A. (2018) Pacific Northwest Insects. Seattle Audubon Society.
Xestoleptura crassipes is a species of flower longhorn beetle. Taxonomically it is placed in order Coleoptera, family Cerambycidae. The species name “crassipes” means “thick-legged.” Adults are attracted to flowers (June-September) and larvae are wood borers, found in forested areas and associated with firs and oaks. Adult body length approximately 10-17mm.
I photographed this specimen on July 16, 2019. It was the only one on the daisy plant by my front door. On the morning of July 18, there remained the single beetle (or I believed it to be the same one). That evening, I observed a 2nd beetle feeding on an adjacent flower. This morning (July 19th, 2019), they were both gone. Perhaps this was a successful meetup for finding a mate. 🌼
Yesterday I had the extreme good fortune to be able to use the scanning electron microscope (SEM) at University of Washington’s Friday Harbor Labs (San Juan Island). We put a Cerambycid beetle under the SEM and “WOW,” the photos were phenomenal! Here’s a few for you to see. Below is a photo of the beetle’s compound eye. Just think of all the information each of those facets receives and processes.
Cerambycid beetle compound eye, imaged under scanning electron microscope at Friday Harbor Labs, San Juan Island, WA
Next, you see an image of the beetle head. It shows the antennal insertion points, the compound eyes, frons, clypeus, labrum, mandibles, and bristly setae.
SEM anterior, dorsal view of cerambycid head.
If you’re interested in learning more about the morphological features, here’s a pretty good diagram below for reference.
image from http://www.faculty.ucr.edu/~legneref/biotact/bc-51b.htm
The last image for you is of the beetle’s tarsi (the foot). This is an important identification feature for many insects. Imagine that! When I was working on my masters degree from the University of Florida, I had an amazing taxonomy professor who was an expert on Coleoptera (the beetles). He created identification keys for Florida beetles and you can take a look at them here: http://www.entnemdept.ufl.edu/choate/beetles.pdf Well, I’m looking forward to using the SEM again and my next imaging will hopefully include the sponging mouthparts of a fly. Stay tuned!