BEETLES 177 



glow-worms are nocturnal, some being able to shine at will ; the males shine as 



they fly, especially about midsummer, while the wingless females crawl on the 



ground, where they emit a light to attract their partners. Very similar to the 



females are the larvae with their flat, broad segments, the hind edges of which are 



faintly spotted. Like the mature insect, they emit their light from the last three 



segments of the abdomen. 



Among the Heteromerous beetles, whicli take their name from 



Meal- Worms. . ,. . .. , „ . . , ,. , , , . , 



having a dissimilar number 01 joints on the tore and the hind 



feet, there being four in front and five behind, the most important forest- 

 types are the members of the family Tenebrionidce. A familiar example of this 

 family in its larval state is the meal-worm. Although these beetles thrive best 

 in dark, wet, or musty places, some are often met with among forests and underwood. 

 In the common tree-fungus, for instance, there lives Biaperis boleti, a bright, 

 black beetle, about one-third of an inch long, convex and ovate, with two waved 

 yellow cross-bands on the elytra, and a yellow spot at the apex, and with pitchy 

 red tarsi. Its larvae eat large pieces out of the funguses in which they live, and 

 develop into complete insects in the holes they make. Not infrequently the larva 

 of another species (Orchesia micans) hibernates and lives in touchwood. This 

 beetle is about a quarter of an inch in length, and is pitchy brown in colour, with 

 silken hairs, finely wrinkled and punctate, the legs and the under-side being a 

 dull red, and the elytra a paler brown. It appears in May, and like its fellows 

 is a good jumper with its hind-legs. 



Spanish Fly or Better known is the so-called Spanish fly (Cantharis vesicatoria) 



Biister-Beetie. w j 1 | c i 1 appears chiefly on the ash, and often strips the very young 

 trees of all their leaves. It occurs in the south of England, as well as in Sweden 

 and Russia, and is not infrequent in June throughout Germany, though mainly 

 known from the south of Europe. In colour it is golden green, or coppery, with 

 black antennae and bluish tarsi, the breast being densely pubescent, the head and 

 thorax having a longitudinal channel, the elytra showing two slightly raised lines, 

 and the length varying from half an inch to an inch. The females of the blister- 

 beetle, as the species is better called, lay their eggs in the ground, where the larvae 

 attach themselves, presumably as parasites, to wasps and bees. The mature 

 beetles are collected in Spain, the south of France, Russia, Sicily, and Hungary 

 for the drug-trade, the gatherers always using gloves, as the mere touch of the 

 beetle will raise blisters on the bare hands. They are used in the manufacture 

 of the various vesicant preparations, and are the basis of most of the lotions 

 for increasing the growth of the hair. Their blister-raising and other medicinal 

 properties are due to the active principle cantharidin, which is deposited mainly 

 in the ovary. Cantharidin is also found in other species, and in a lesser degree 

 in the lady-birds ; it is so powerful in its effect that a hundredth of a grain will 

 raise a blister on the lip. 



„ A third section of beetles, the Tetramera, comprises those in which 



Weevils. . . . „ . . 



the tarsi have apparently four, but in reality five joints, one being 



very small and hidden, while the anterior tarsi have sometimes only three joints. 



The members of one family of the group, the weevils (Curculionidce), which are 



extremely numerous and very injurious insects, are distinguished by the head being 



vol. 1. — 12 



