36 



numerous colony may require a nest 1 ft. long and 6 inches 

 wide, a conspicuous object on the tree, especially when most 

 of its foliage has been devoured. The caterpillars shelter in- 

 side these nests buti they may often be found sunning 

 themselves on the outside, where they also cast their skins (as 

 they must from time to time when growing). Their fondness 

 for sunning themselves is also shown by their habit of lying, 

 many together, along any exposed branch. 



Throughout their existence the pests feed voraciously, de- 

 vouring leaf by leaf, so that in some cases the tree is stripped 

 bare- of foliage and almost smothered in web. When full-fed 

 in the latter half of June or early July each caterpillar spins 

 a silk cocoon (Fig. 4), yellow or white in colour, between 

 leaves on the tree, on the trunk, on a neighbouring fence, or 

 among grass and other herbage. Inside the cocoon the cater- 

 pillar turns to a blackish-brown chrysalis (Fig. 5) from which 

 the moth emerges some three weeks later. 



Natural Enemies. Lackeys, in the egg or caterpillar 

 stages, are attacked by numerous enemies which consist chiefly 

 of such other insects as Ichneumonid, Braconid or Tachinid 

 flies. Sixteen or more kinds of Ichneumon fly have been found 

 to destroy them and at least two kinds of Braconids related 

 to those which parasitise White Butterflies (making the small 

 yellow cocoons so often found beside the dead or dying butter- 

 fly caterpillars). Lackey caterpillars do not seem to be readily 

 eaten by birds, but of course are subject to disease. It is 

 not yet known whether the sudden epidemics are due to a 

 temporary lack of natural enemies or to favournble weather 

 conditions, but it is clear at present the pest is riot always 

 kept in check by these means. 



Control Measures. 1. Spraying is effective if carried out 

 early enough, and also at any time if there are not many cater- 

 pillars on the tree. When, however, the whole tree is enveloped 

 in webbing it is impossible to get enough poison on to the 

 leaves to do any good. The best time to spray is within three 

 weeks after the dropping of the petals from the flowers. Lead 

 arsenate (1 Ib. paste to 20 gallons water) is the best insecticide 

 to use and the wash should be applied through a fine nozzle, 

 giving a light dressing to every leaf on the tree. 



2. Nest Destruction. In gardens with only a few trees 

 affected, the nests can be destroyed by hand, taking care that 

 caterpillars which fall do not escape. Nest destruction is also 

 necessary in orchard epidemics where spraying could not be 

 carried out sufficiently early. Sometimes the trees are first 

 banded with sticky material to prevent fallen larvae from 

 crawling up again, and in cases where the trees- are very high 

 shot-guns have been used to destroy the nests. Naturally 

 nest destruction is ruinously expensive in commercial orchards 

 but it has on several occasions beeri necessary to resort to it. 



