This presentation briefly reviews the primary insect pests of drying and stored raisins, and how to manage them.

1. Stored Raisin Product Pests
Matthew Fidelibus
Viticulture and Enology, UC Davis

2. Two Categories of
Raisins Pests
• Insects that primarily feed on drying raisins
– Includes Driedfruit Beetle and Raisin Moth
• Insects that primarily feed on dried raisins in
storage
– Includes Indianmeal moth and Sawtoothed Grain
Beetle

3. Driedfruit Beetle
• Carpophilus hemipterus L. (Coleoptera:
Nitidulidae). Cosmopolitan sap beetle.
• Larvae feed on ripe and overripe fruit
including grapes, stone fruit, figs, dates,
melons and citrus.
• Adult beetles are attracted to volatiles from
fermenting fruit, including bunch rot of grapes
• Fruit must have >30% moisture; living yeast

4. Adults are dark brown, about
3 mm long, and oval shaped.
Short wing covers leave the
tip of their abdomen exposed.
Light brown or amber colored
spots on their wing covers.
Legs and antennae are reddish,
and antennae are knobbed at tips.
Dried Fruit Beetle

5. Driedfruit beetle larva
Adult females scatter
eggs over raisins.
Larvae feed on
the flesh of the
underside of berries
on drying trays.
Fully grown larva enter
soil to pupate; adults
emerge 8 days later.
Feeding, excreta, and
cast skins reduce raisin
quality.

6. Controlling Driedfruit Beetle
• Well-dried raisins, free of bunch rots, will
minimize infestation
• Attract and kill systems with fermenting baits
• Stack and seal boxes of raisins with airtight
plastic or reinforced paper laminate
• Stacks may be fumigated with phosphine
• Controlled atmosphere (low O2 or high CO2),
or controlled temperature (2 weeks at -18 ◦C)

7. Raisin moth (Cadra figulilella)
• Larvae feed on ripening and drying grapes,
and raisins stored on farms.
• Adult females lay eggs on drying grapes. High
day-time temperatures may kill exposed eggs.
• Fully grown larva leave the raisins, pupating in
dark, dry cracks.

8. Raisin moth damage
• Larvae on stored raisins feed chiefly on the
ridge crests of the raisins, but may also bore
into the flesh.
• They do not completely consume raisins but
move about, leaving masses of excreta and
webbing.
• One larva can damage about 20 Thompson
Seedless raisins.

9. Raisin moth (Cadra figulilella)
Adults are about 10 mm
long, with a 16 mm wing
span.
Forewings are light pinkish
gray with indistinct markings.

10. Raisin moth eggs

11. Raisin moth larva

12. Raisin moth larva detail

13. Raisin moth in pheromone trap

14. Raisin moth control
• Clean up and destroy leftover grape bunches
and other fruit in and around the vineyard by
autumn, before larvae leave the fruit for
overwintering sites.
• Well dried raisins are less attractive to moths
• Dried raisins in bins should be covered
• Cleaning operations at packinghouse can
greatly reduce egg and worm numbers

15. Indianmeal moth
(Plodia interpunctella )
• Indianmeal moth is one of the most
destructive stored raisin pests worldwide.
• Moths lay eggs on raisins in the field and in
storage
• Young, first-instar larvae can enter crevices as
small as 0.13 mm (1/200 inch), thus infesting
commodities in containers thought to be
insect-proof.

16. Indianmeal moth and pupa

17. Indianmeal moth damage
• Infestations contaminate raisins with
excrement, cast skins, webbing, cocoons, and
living or dead larvae.

18. Indianmeal moth management
• Sanitation is key.
• Infestations are reduced by processing steps,
including stemming, cleaning, etc.
• Heavily damaged raisins are lighter in weight
than undamaged raisins and can be blown out
during processing.
• Cleaning storage, processing, and shipping
facilities helps minimize infestations

19. Sawtoothed grain beetle
(Oryzaephilus surinamensis)
• Cosmopolitan pest that feeds on practically
any stored dried food.
• Adults are 3 mm long, narrow and flat.
• Crawls rapidly but does not fly.
• Adults are long lived—up to 3 years.

20. Sawtoothed grain beetle
• Eggs are <1 mm; larva are yellowish white.
• Newly hatched larva can pass through very
narrow crevices.
• Feeds on all parts of a raisin.

21. Sawtoothed grain beetle

22. Sawtoothed grain beetles

23. Sawtoothed grain beetle
management
• Sanitation and fumigation.

24. Conclusions
• Good drying and strict sanitation practices, from the
vineyard through the packinghouse, will help
minimize infestations.
• Stored raisins may be disinfested by fumigation.
• Fumigation may need to be repeated periodically,
when storage exceeds 60 to 90 days, or after the seal
has been disrupted.

25. Reference for further details
• Grape Pest Management, third edition
• http://ucanr.edu/GPM