We teach the importance of identifying a pest in order to develop an effective pest management plan. An accurate ID leads to learning about the pest's lifestyle including host range and numbers of generations per season. Occasionally, a significant insect pest somehow continues to fly below the radar of insect taxonomists.
Such is the case with the "Sedum Flea Beetle." I'm using quotes because I've never found a reference assigning both a scientific as well as the common name to the beetle. This is my own made-up common name, but it captures the host range that I've observed thus far.
Purists will recognize that I'm bending plant taxonomy rules a bit by ignoring the fact that the genus Sedum no longer applies to many stonecrop plants used in landscapes. However, gardeners commonly refer to stonecrops as sedum whether the plants belong to the Sedum or Hylotelephium genera.
I first came across the beetle in mid-October, 2011, after receiving a phone call from a homeowner in eastern Cincinnati who said brightly colored beetles were destroying her "sedum." I visited and found that a flea beetle was doing so much damage the only way I could identify the defoliated plants was through a plant tag; it was Hylotelephium telephium ‘Autumn Joy’ (family Crassulaceae). There was little joy in the appearance of the landscape planting.
Last year, I received a report in mid-June that the same beetle was damaging 'Autumn Joy' and 'Munstead Red' in a landscape in Dayton. I visited in mid-June and found both adults as well as larvae. This season I've gotten e-mail messages with pictures showing the beetle on unidentified stonecrop plants in a suburb of Dayton and in western Hamilton County.
The reports and observations I've made thus far; in mid-June and mid-October, strongly indicates the sedum flea beetle has at least two generations, if not more. This may also explain why the plants I observed in October were so heavily damaged. The population along with the damage escalated with each succeeding generation.
The sedum flea beetle looks very similar to the Passionflower Flea Beetle (Disonycha discoidea, family Chrysomelidae). You can see some good pictures of this beetle posted on BugGuide by clicking on this hotlink:
However, the authors of Host Plants of Leaf Beetle Species Occurring in the United States and Canada (Clark et al. 2004) note that the passionflower flea beetle only feeds on passionflowers (family Passifloraceae) including Passiflora incarnata and P. lutea. Neither Sedum nor Hylotelephium is listed as hosts for any of the 31 flea beetle species in the Disonycha genus.
In fact, the home gardener in western Hamilton County noted she is only finding the beetles on sedum. She has not found them feeding on a passionflower growing in her landscape.
Based on reports I've gotten thus far, I've concluded this beetle has the potential to cause significant damage to various stonecrop plants. I don't know if the recent reports were plants belonging to the Sedum or Hylotelephium genera.
I'd like to learn more about this beetle as well as its host range. If you see the sedum flea beetle, please drop me a note with your location and contact information. Also, if possible, include the identity of the host plant (is it Sedum or Hylotelephium). Just click on my name at the top of this Alert and then click on my e-mail address.