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Bug of the Day: White Grubs

White Grub larvaWhite Grubs, or simply "grubs", are actually the larva form of scarab beetles. While there are thousands of different species, their basic life cycle is the same:

  • April: third instar larvae burrow up from below the frost-line where they have been waiting all winter
  • May: larvae continue to feed on plant/grass roots
  • June: pupate for 1-3 weeks to metamorphize into beetle
  • July: emerge as beetle and feed on plant leaves
  • August: lay eggs for next season, 30-40 per female
  • September: emerge as first instar larvae and feed
  • October: molt every 1-3 weeks until full grow larvae (third instar)
  • November: burrow below frost line and wait for Spring

These insects are most vulnerable during their first months as a larvae, so spraying during the Fall is highly recommended. I have read several pest control sites that say spraying during the Spring is pointless - the larvae are just too resistant in their mature and/or pupa form.

The picture in this entry is actually taken by me - we found this little guy in one of our potted plants from last year while gardening over the weekend. You can view two larger pictures, where fine hairs can be seen. I am told that entomologists can use the patterns of these hairs to identify the species of beetle.

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