202 PROTECTION OF WOODLANDS. 



barrel-shaped cocoon inside a nest or pupal community spun by 

 mutual labour, and attaining about the size of a child's head. 



The moths swarm in August, and are, like other moths, usually 

 most active towards evening. After impregnation, the female 

 deposits about 150 to 200 ova in rows along the deep fissures in the 

 bark of old Oak trees, and covers them up with a little grey 

 wool-like coating as a protection against the wintry cold. 



In the following May the young caterpillars make their 

 appearance, and at once commence feeding in large communities. 

 During the day-time they generally collect closely together in a 

 nest in common on the stem, situated just under the junction of 

 one or other of the large branches, and then towards evening 

 setting out in close phalanx-like column to re-commence feeding. 



The column is generally headed by one caterpillar, but gradu- 

 ally increases to the middle, and then, after decreasing, again 

 terminates in another single caterpillar ; in this marching order 

 the caterpillars range themselves closely together, and whenever 

 the column is broken or disturbed, they endeavour to re-form in 

 proper order again as soon as possible ; their track or marching- 

 route is marked by gossamer threads. After they have finished 

 feeding, they usually march back to the same nest, which is 

 gradually increased in dimensions and woven together more closely 

 as the caterpillars grow larger, so that at last it attains the size of 

 an infant's head, and can plainly be seen from a distance. Such 

 nests in common usually contain a good deal of larval excrement. 

 When the tree they happen to be on has been denuded of foliage, 

 the caterpillars migrate to another, still moving always in closed 

 column. 



About the beginning of July the pupal state of rest is entered 

 into by the colony, either in the nest in common which they 

 happen to be occupying, or in a new one specially woven for the 

 occasion either at the foot of the bole or else at some height up 

 the stem, but always on the sheltered side of the tree ; inside this 

 nest in common each caterpillar forms, as already stated, its 

 individual cocoon, from which the complete moth emerges in 

 August. 



It is only the Oak that is attacked by this insect, but as it 

 occurs not infrequently, the injuries inflicted can assume consider- 

 able proportions. Trees in the full enjoyment of light and air 

 are, on the whole, most exposed to attacks from the processionary 



