1 48 General characterisation. By Dr. A. Seitz. 



slightly curved small band bounds the marginal area. But very often this pattern is replaced by an excellent 

 protective colouring, the conspicuous white discal spot being only reduced or quite obsolete, and the trans- 

 ver.se bands modified into markings imitating the venation of leaves. In Epicnaptera, Gastro pacha, etc., the 

 ving has exactly the appearance of a diy leaf, and when at rest the insect is very difficult to perceive. 



Although resemblance to parts of plants, pieces of bark, etc., is widely distributed among the Lasiocam- 

 pids, we meet with no sign of mimicry. There is indeed not a single insect of any protected family which the 

 Lasiocampids resemble even accidentally or quite superficially. 



The Lasiocampids are very prolific, as in all the species the 59 lay a large number of eggs. According 

 to the weather, this numerous progen}'^ cither produces one or several broods or succumbs to diseases, especially 

 flacherie and fungus, such as Isaria farinosa and Botrytis bassii. These diseases frequently already decimate 

 the young larvae, but often large numbers of them grow up until they are ready to pupate, when a large 

 percentage of them dies. Every collector wonders at the huge numbers of blue-haired larvae of Macrothylacia 

 rvhi found in the autumn. Almost every larva leaving in June the egg, which is laid in clusters of hundreds, 

 flourishes throughout the summer and hibernates in October; but only a restricted Jiumber of moths appears in 

 May to propagate the species. Much the greater number of larvae casually met with in the winter is diseased, 

 being infested with the white mycelium of fungus, and often bearing parasitic vegetation, which protrude from 

 the stigma and between the segments as white threads and club-shaped growths. 



Beside these plant-parasites the larvae of Lasiocampids are much decimated by parasitic insects, espe- 

 cially Tachinids, some of which are almost entirely confined to the Lasiocampid larvae. The largest of our 

 Eiu'opean Tac-hinids, E'jhinomyia grossa, nearly always hves in the larva of Lasiocampa trifolii; and Masicera 

 pratensis is especially abundant in Cosrnotricha potatoria, etc. Many parasites, especially Ichneumons, may 

 be regarded as the protectors of the forests, as they prevent the increase of such noxious insects, •especially 

 the genus DendroUmus. The appearance of large numbers of Lasiocampids in especially favourable seasons 

 is in some cases without any practical importance, e. g. the armies sometimes met with in the higher Alps of 

 Malncos. alpicola, which feeds on herbage. But if noxious insects appear in such masses, enormous devasta- 

 tions may be the consec^uence. The genus to which Dendr. pini belongs is notorious for this, and these injurious 

 species at once appear in districts devoid of forests as soon as woods of the food-trees are planted, and it is astonish- 

 ing to observe in how short a time a species usually occurring in single specimens multiplies to such an ex- 

 tent that even the most energetic measures against the pest are mthout success. At the season of flight the 

 ground in the woods is covered with dead specimens and masses of wings, and at night the moths swarm about 

 the lights and street-lamps in dejise clouds like snow-flakes in a storm. Where the climate renders it impossible 

 to fight against the plague of larvae, for instance by putting lime-rings around the trees, the forests are often 

 doomed and the cultivation of the food-plant has to be abandoned. 



In the temperate region the Lasiocampids have only one brood ; but in many species it is easy to force 

 (lie larvae so that a second artificial brood may be obtained, which is often visibly different from the first. As 

 an exceptioia so-called incomplete summer-broods also occur in Nature, some larvae developing more quickly 

 and giving the moth in the same summer, while the more slow-growing specimens do not emerge until the next 

 year. It is decidedly necessary for the Lasiocampids to pass the winter as larva and not in the pupal stage. 

 Species the larvae of which are full-grown in the autumn remain in that state throughout the winter and do 

 not pupate until the spring, often, as in Macrothylacin rubi, witliout taking any more food worth mentioning. 

 Sometimes the moth still appears at the very end of the season; e. g., Eriogaster rimicola emerges in October, 

 and Poecilocampa popiili in November. Eriogaster lanestris normally flies in the winter, and its Alpine variety 

 arhusculiie only emerges on mild Avinter-days, or if svich days do not occur, sometimes remains in the 2JU2)al 

 stage ten years or even longer. 



The moths are short-lived. The larva, usually very large in proportion to the moth, stores an enor- 

 mous quantity of fat. The ^J very soon swarms about in search of a ^ ; exceptionally it may copulate more 

 than once, but soon afterwards dies, while the $ is occupied for some time with depositing a large number of 

 eggs. The eggs are often laid in clusters, sometimes, however, also singly, and occasionally pasted around 

 small twigs side by side, forming regular rings {MaJacosoma neustria). As regards the food of the larva, the 

 family is poh^hagous, attacking trees and herbs, deciduous and indeciduous trees, Monocotjdedons and Dicoty- 

 ledons. It has even been said of Macrothylacia ruhi to have gnawed at moss, which is shunned by nearly all 

 other larvae, and to have attacked artificial vegetable products, such as bread. 



Apart from the interruption caused by the winter, the growth of the larva of the Lasiocampidae is 

 very regular and rather slow. The larvae of Macroth. ruhi, which emerge from the egg in June, are not full- 

 grown until the end of September or October, i. e. after about 14 weeks ; those of Lasiocampa. quercus, appearing 

 in July, are not ready to pupate until the following June, and the larvae of Gastrop. quercifolia appear in June 

 and feed until the end of May, excepting the winter months. The length of the larval stage explains the inca- 

 pacity of nearly all Lasiocampids to produce a second brood in the cooler districts. 



Pupation takes place in a carefully spun cocoon often of a very regular shape (Lasiocampa. Eriogaster, 

 Diplura); the hairs of the larva arc often used, being placed in an erect position on the surface of the cocoon. 

 In DendroUmus the aoiculate spines of the blue collar of the larva are often woven into the cocoon, so as to 



