My home was infested by this kind of tiny beetles, which is only 3.5-4mm in length. I found them mining in a pack of expired chocolate bar and they can tear open aluminum foil.  Later on I found them crawling out from a pack of catnips. They are very active flyers and drawn to light.  They may be reproductive as I still saw them occasionally after throwing their food source away weeks ago.



[ 本帖最後由 sunnet 於 2015-10-1 09:43 編輯 ]

I think this is the tobacco beetle (Lasioderma serricorne (Fabricius, 1792), Family Ptinidae) rather than a scarabid beetle.   May I know more about the chocolate bar.   Is it chocolate with nut? If yes, what kind of nut?   Or if it is just a chocolate bar without nut, is it dark chocolate or white chocolate?   Just curious.

Nadia, thank you so much again!!  
Honestly I really didn't know whether the chocolate bar had nut or not. It was not a common brand from HK. The foil was in cute Halloween design so I guessed it was milk chocolate for kids, a leftover from last year probably.  It was kind of disgusting as the bugs could drill holes and created some tunnel from the surface of the foil paper. I think Tobacco beetle does make sense. The GIMPET catnip pack was some kind of shredded plant just like tobacco inside the cigarette.  I suspected the beetle was came from either the catnip or the chocolate. I was surprised how the beetle could find and infest the second food source for the location was far apart.

[ 本帖最後由 sunnet 於 2015-9-30 16:58 編輯 ]

Oh yes, this beetle feeds on many 'things' of plant origin, including paper boxes if they are hungry.    It was known to me to feed on a chocolate bar with almond in the past and I'm interested to know whether they wanted the nut or the chocolate.   From what you described, it seems that can feed on just chocolate without the nut.   Many locals like to keep beans (red, green, broad, black), herbal medicine, soup ingredients and many other kinds of health food of plant origin at home.   If they were not kept in the fridge or in boxes, these tiny beetles will find their way to them eventually.   Thus inside the city, there are always a large number of nuclear stocks of this beetle everywhere.   It is extremely rare for any people living in Hong Kong without coming into contact with this beetle before, although usually it is the mom or domestic helper who discovers it first and throw everything away.

You are right. I did find this kind of beetle crawling from paper wrapper of Chinese medicine pack before and simply disposed the whole thing.  Found a record in the FEHD website too.

http://www.fehd.gov.hk/english/s ... a%20serricorne.html