Ix] Butterflies and Moths 99 
been thinned. It is very noticeable after thinning as 
gaps are made in the rows. The caterpillars may be 
found by hunting in the soil near freshly damaged plants. 
Later on in the season they attack the swollen roots of 
turnips and mangolds by scooping out large holes. In 
a similar manner potato tubers are attacked. The 
Fig. 29. Caterpillar pupa and adults of a surface caterpillar moth. 
nibbled roots and potatoes usually rot. Corn crops often 
suffer from attacks on their roots in mild winters. The 
grubs remain hidden under the surface or under leaves 
during the day and come out to feed at night. The 
moths giving rise to these usually fly at night and are 
attracted by lamps or fires. Their hind wings are 
lighter in colour than the front ones. The female has 
7—2 
