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Diamond-back moth

The diamond-back moth (Plutella xylostella) is a pest of brassica crops including oil seed rape. It is a relatively small moth so the eggs can be hard to find. Newly-hatched caterpillars burrow into the foliage to feed but then come out onto the leaf surface as they grow larger and cause characteristic ‘windowpane’ damage (second image down).

The diamond-back moth does not overwinter very successfully in the UK and infestations in early summer usually arise as a result of migrations from continental Europe (Chapman et al., 2002). These occur when the wind direction is favourable and when there is a large population of moths ready to migrate.

In 2018 diamond-back numbers are going to be monitored in two ways:

The diamond-back moth completes its life-cycle fairly rapidly – development times in days for the different life stages at different temperatures (data from Liu et al., 2002) are shown below.

Temperature oC Development time in days Development time in days Development time in days Development time in days

Egg Larva Pupa Total
8 20.8
10 15.4 42.4 29 86.8
12 12.8 30.8 21.2 64.8
14 8.4 19.8 12.7 40.9
16 6.4 16.1 10.6 33.1
18 4.7 14 7.9 26.6
20 4 11.3 6.3 21.6
22 3.5 9.3 5.3 18.1
24 3 7.7 4.5 15.2
28 2.4 6 3.6 12

Further information

Liu et al., (2002). Development and survival of the Diamondback Moth (Lepidoptera: Plutellidae) at constant and alternating temperatures. Environmental Entomology 31, 221-231.

Chapman JW, Reynolds DR, Smith AD, Riley JR, Pedgley DE and Woiwod IP (2002). High-altitude migration of the diamondback moth, Plutella xylostella, to the UK: a study using radar, aerial netting and ground trapping. Ecological Entomology 27: 641-650

INRA Factsheet

CABI datasheet


Adult diamond-back moth
Caterpillars and damage
Damaged plant
Moths captured in light trap June 2016
Moths captured in pheromone trap June 2016