INSECTS 



The larva of the drinker moth {Odonestis potatoria, Linn.) when about half-grown may be often 

 seen resting on a twig of some sort, apparently waiting for the time when its old clothes will be 

 rent asunder, to appear in its new dress ; but sometimes we find a stop to the progress has been 

 made by the larva of an ichneumon fly [Rhogas geniculator, Nees) within, attacking some vital part 

 and causing its death ; there it remains, and in the course of a week or two the lodger within will 

 cut an opening out of its back and escape, ready to repeat the same tactics on another unfortunate 

 larva ; probably Arctia villica, Linn., may be selected, for the same species of parasite destroys both. 



The eggs that are deposited externally on nearly or quite full-fed caterpillars as a rule do not 

 hatch until the victim has prepared a place in which it intends to complete its metamorphosis ; 

 if, on the other hand, they should have hatched, the development is very slow to enable the cater- 

 pillar to proceed as if it were not attacked. The puss moth {Dicranura vinula, Linn.) is often 

 attacked by these external parasites, Paniscus cephalotes, Holmgren, and P. testaceus, Gravenhorst. 

 The caterpillar of the puss moth when full-fed makes its cocoon generally on the bark of a tree, 

 excavating a portion. The bark that is removed in the excavation is utilized by mixing it in with 

 the silk first produced to form an outer covering ; subsequently the spun silk is rubbed over by the larva 

 with formic acid, the fluid secreted in the prothoracic gland, which changes the fibrous character of 

 the silk to the tough, hardened, gelatinous material of the ordinary cocoon of this species. In this 

 cocoon the parasites just mentioned lie side by side in their black envelopes until they are ready to 

 emerge. In the genus Lissonota the cocoons made by the larvae are long oval, measuring 44 mm. long 

 and 4 broad with a bright polished surface. Those of the genus Ophion are much stouter and contain 

 several distinct layers in their manufacture, the outer one composed mostly of flossy silk ; the remainder 

 are like so many layers of ' gold-beaters'-skin,' each layer appears to be put on in a fluid state, or the 

 silk woven, afterwards covered or smeared over with formic acid, the acid dissolving the silk and 

 givmg it the appearance of ' gold-beaters'-skin.' It is insoluble in hot or cold water, alcohol, ether, 

 or chloroform. It is soluble in strong acids, being most readily dissolved in hot nitric acid, also in 

 strong alkaline solution, preferably caustic potash. It contains moisture, nitrogen, a trace of sulphur, 

 and on destructive distillation leaves about half its weight of carbon ; would, therefore, contain 

 C, H, O, N, and S in certain proportions. 



Stems of plants, cow-parsnip [Heradeum sphondylium), also afford protection for the cocoons of 

 Lepidoptera {Depressaria heradeana), consequently they also afford security for the parasites infesting 

 the larvae — Ichneumon heradiana, Bridgman, with a short ovipositor and Pimp/a strigipUuris, Thorns, 

 with a long ovipositor. 



Even caterpillars that are hidden deep in the solid wood of growing trees are not free from the 

 attacks of the ichneumon fly, any more than those that are exposed on the surface of the leaf. They 

 are certainly more difficult to get at. But once the caterpillar is discovered by the inquisitive fly, 

 Rhyssa persuasoria, or its allies, so sure is the attempt made to deposit the egg in the hidden larva ; 

 this is done by forcing her delicate ovipositor, not so large as the finest needle made for domestic use, 

 through the solid wood into the caterpillar below. It is almost beyond belief that a fly with an 

 ovipositor nearly two inches in length can thrust it into the solid wood of a growing tree the whole 

 length, if necessary, to reach its victim ; yet she does it. The genus Perithous, Holmgr., has also a 

 long ovipositor, and is assigned by nature to attack those little bees and wasps that make the decayed ' 

 stems of bramble and rose their nidus, in which they pass the winter in their larva or maggot stage ; 

 while those wasps and bees that make their home in old walls or earth banks have the attention of 

 a very curiously-formed parasitic fly, by name Foenus jaculator, Linn., whose abdomen seems to 

 proceed from the middle of its back ; that and its long ovipositor, also abnormally hind legs, with 

 the apex of the tibia flattened or spatulated, giving it a very grotesque appearance. Spiders also 

 receive attention from the Ichneumonidae ; HemiteUs fragilis and similis, Gravenhorst, are common 

 parasites in the egg bags of our ' domestic spiders,' Zilla x-notata, Clerck, and others. * Hunting 

 spiders,' Ocyale mirahilis, Clk., Lycosa pullata, Clk., and others of the group are kept under 

 by Hemimachus fasdatus, Fabricus, Pezomachus mkrurus, Foerster, and P. xonatus, Fourcroy, 

 attacking the egg cocoons. Orb-weavers, Epe'ira cornuta, Clk., whose habitation is beautifully 

 concealed, in which the spider makes her egg cocoon, do not escape the prying eyes of Pimpla 

 epeira, Bignell. The eggs are not touched, it is the young spiderlings that are consumed by the 

 remorseless Pimpla. 



It seems an anomaly to write about flies attacking spiders, and yet at the proper season it must 

 be a daily occurrence. The writer perhaps is the only living naturalist who has ever been an eye- 

 witness of an attack, and it may be interesting to here record how the ichneumon fly obtains its 

 end. Having selected a spider sufficiently large in which it has some confidence, she approaches 

 it carefully, but the spider, objecting to the confidence trick, drops from its hiding-place on the 

 bough of the tree by the usual silken cord. The ichneumon fly does not appear in the least troubled 

 on that account, no doubt having had previous experience. Taking advantage of the spider's rope, 

 she very leisurely walks down to the spider and apparently coaxingly touches it with her antennae. 



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