TUR PESTS. 143 



The lifo history appears to be a short one and broods probably 

 succeed one another rapidly. The increase of the insect is chccke'l by 

 hymenopterous parasites. 



No precautions are possible once the fly has laid eggs in the pods. 

 Nothing- can then be done to destroy the insect without destroying- the 

 pods also. It is unlikely that the insect causes serious harm in large areas 

 of tur. Much has to be learnt of this insect before preventive measures 

 can be devised. 



Tur Leaf Caterpillar.^ 



This caterpillar feeds upon the small upper leaves of the tur plant, 

 webbing- them together into a small compact mass within which it lives. 

 The webbed leaves are very conspicuous so that the pest is at once 

 recognisable. 



The moth lays eggs on the upper leaves, the eggs being laid sing-ly, 

 scattered over many plants. A small white caterpillar hatches, which 

 feeds upon the leaf. It draws together the very small leaves at the tip 

 of the shoot in the usual way characteristic of caterpillars ; commencing 

 with two leaves close together, it rapidly draws a thread between them, 

 the thread being of soft gummy matter, exuded from the lower lip of the 

 insect ; first touching one leaf with the end of the lower lip it affixes the 

 gummy matter, draws it rapidly across to the other leaf and so produces 

 the first thread ; it then returns, bringing a second thread to the first 

 leaf and continues to move from one to another, producing small threads 

 which rapidly dry and so contract ; as the first threads dry they pull the 

 two leaves together and the later threads are shorter ; all the threads as 

 they dry shorten and their united pull eventually brings the two leaves 

 together ; the caterpillar then commences on a new leaf, and draws that 

 close to the two previously webbed ones, so continuing- till it has prepared 

 its habitation. Within this knot of leaves the caterpillar lives ; it orows to 

 a length of one quarter of an inch, smooth, with no markings, the head 

 brown, a very small prothoracie shield and the body a yellow tendino- to 

 orange. When full fed it pupates within the twisted leaves and a tiny 

 dark-coloured moth emerges. This moth is never seen in the fields 

 being very small and coming out only at night or in the dusk. 



This pest attacks the young tur plants in July, August and Septem- 

 ber. It produces a very characteristic form of injury, which is of little 

 importance unless the top shoot is so drawn into the knot that it is killed. 

 When only side leaves are drawn in, the leaves alone are killed, but where 

 the top shoot is affected, it is bitten throug-h and side shoots are 



143. Hucelis critica. Meyr. (Tineidse,) 



