Ten Lined June Beetles: Unseasonal Appearance!!!

A dozen ten lined June bugs in my basement (so far) in October!!
Location: South Eastern Idaho
October 24, 2011 9:03 pm
We recently purchased a 100+ year old home. The home had been vacant since the spring. When we installed a new furnace and brought the home up to temperature last week 10/15/11 I noted a few days later several large bugs lying around in the basement. All were dead or nearly dead when found. I looked around and noted that in the area of the basement where the concrete floor doesn’t cover that there are some bore holes, about the size of an adult’s finger into the clay floor in this area. I was surprised to find them all dead and even more surprised once I found a picture on your website that let me guess what kind of bug it is.
Am I seeing an infestation? Are they waking and dying because we warmed up the home and they think it is spring? Will I have this happen over and over or are these beetles going to exhaust thier numbers after this false spring?
Signature: Rick

Ten Lined June Beetle

Hi Rick,
Since the larvae and pupae of the Ten Lined June Beetle live underground for several years, and since the ground temperature is a significant factor in the emergence of insects that live underground, it is likely that heating the basement triggered an early emergence for the brood of Ten Lined June Beetles you found in October.  We suspect that the clay floor might have provided a suitable location for a female to have laid eggs since the grubs feed on the roots of trees and shrubs.  We strongly doubt that the eggs were laid outside and the grubs tunneled to your basement.  We think it is more logical that at some point a female was trapped in the house and laid eggs on the floor.  We doubt that this pattern will repeat in future years, though it is entirely possible there is an isolated population of Ten Lined June Beetles that have been cyclically reproducing in the home if the required roots are near the surface of the clay floor.

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