© Stuart M Bennett 2003
Trogoderma variabile
(Warehouse Beetle)

What's going on I hear someone say, the picture above is virtually the same as the Khapra Beetle and you would be correct because: Adults of warehouse and khapra beetle can only be distinguished by dissection of the genitalia (sounds painful) or by DNA methods. Adult warehouse beetles can live for up to 100 days, although average longevity is between 9 to 50 days depending on environmental conditions.

Larvae of both Khapra and Warehouse Beetles are similar in appearance and can only be separated by expert dissection of the mouthparts. Larvae of both species are approximately 7 mm in length and both have characteristic tufts of body hair. The colour of the larvae changes from yellow-white of the first instars (an instar is that form the insect takes at that point in development) darkening to red-brown of the final instar. Larvae of both species can enter diapause (suspended development) triggered by unfavourable environmental conditions such as low temperatures, crowding and starvation. Larvae entering diapause will usually seek out crevices for protection and can remain in diapause for several years. The survival of larvae through diapause makes eradication very difficult.

Top and underneath views of both adult and larvae

Warehouse larvae having dinner out on some egg noodles


Fumigation using methyl bromide is the treatment of choice. Because of warehouse beetle's habit of hiding in cracks and crevices and infesting porous block, the entire structure, in addition to its contents, must be fumigated. Typically, the building is covered by tarpaulin or heavy grade polythene and the fumigant is pumped in at an approved rate, typically six to nine pounds per thousand cubic feet, depending upon temperature. The process may take several hours, depending on the size of the building and the strict safety precautions required. The future for the continued use of methyl bromide fumigation for khapra beetle and warehouse beetle is uncertain at this time as it is not as effective if the larvae are in diapause.


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