314 INSECTS AT HOME. 



is bright oclireous yellow, -with the exception of a broad 

 satin-like belt round the middle, the colour being black, 

 glossed with violet. The boring instrument is brown, with a 

 slight tint of red in it. The femora, or thighs of tlie legs, are 

 black, and tlie rest yellow, and tlie antennae are yellow. Even 

 the wings have a decided yellow tinge about them. 



The reader may remember that most wood-boring insects are 

 exceedingly variable in size. The Sirex is no exception to the 

 rule, for, while some specimens are almost gigantic in dimen- 

 sions, others are the merest dwarfs by their side. 



The larva bears some resemblance in general form to that of 

 the Musk Beetle, described on page 195. The mandibles are 

 very strong, and furnished with saw-like teeth at the end, thoir 

 action being as remarkable as it is powerful. They remain in 

 the larval state for a considerable time ; but the duration of the 

 pupal existence depends much on circumstances, those which 

 change to the pupal condition in the summer only waiting a 

 month or so, while those which change at the end of autumn 

 have to wait for nearly a year. 



As a rule, none of the species of Sirex are very common in 

 this country. They are, however, tolerably plentiful in the 

 neighbourhood of my house, because there is a small fir-wood 

 within a hundred yards of it, and that wood has been fenced 

 off by a paling made from the misshapen firs. That tliey may 

 be thus locally common may be seen from an account published 

 in the first volume of the ' Transactions of the Entomological 

 Society.' A part of a fir-tree, some twenty feet long, was placed 

 in an outhouse, and for several months the Sirex juvencus issued 

 at the rate of five or six j)er diem. At first they were nearly 

 all males, then a few females appeared, and during the last two 

 weeks, i.e. the end of November, females alone made their 

 appearance. The piece of wood in question was sent to the 

 Society by Mr. Eaddon, from Bewdley Forest, Worcestershire. 



An enormous group of Hymenoptera now comes before us, 

 appropriately entitled Entomophaga. This name is formed 

 from two Grreek words, signifying ' insect-eating.' It is given 

 to them because, in the larval state, the greater number 

 of them are parasites within other insects ; usually, but not 

 always, attacking them while still larv^. In them the abdomen 



