OBSERVATIONS ON INSECTS AND VERMES. 413 



There are many instances of the great service these little insects 

 are to mankind in reducing the number of noxious insects, by 

 depositing their eggs in the soft bodies of their larvcej but none 

 more remarkable than that of the ichneumon tipulce, which pierces 

 the tender bodies and deposits its eggs in the larva of the Tipula 

 tritici, an insect, which, when it abounds greatly, is very prejudicial 

 to the grains of wheat. This operation I have frequently seen it 

 perform with wonder and delight. MARKWICK. 



BOMBYLIUS MEDIUS. 



The Bombylitts medius is much about in March and the beginning 

 of April, and soon seems to retire. It is an hairy insect, like a 

 humble-bee, but with only two wings, and a long straight beak, 

 with which it sucks the early flowers. The female seems to lay its 

 eggs as it poises on its wings, by striking its tail on the ground, 

 and against the grass that stands in its way, in a quick manner, for 

 several times together. WHITE. 



I have often seen this insect fly with great velocity, stop on a 

 sudden, hang in the air in a stationary position for some time, and 

 then fly off again ; but do not recollect having ever seen it strike 

 its tail against the ground, or any other substance. MARKWICK. 



MUSCLE. FLIES. 



In the decline of the year, when the mornings and evenings 

 become chilly, many species of flies (Miisccz) retire into houses, 

 and swarm in the windows. 



At first they are very brisk and alert ; but as they grow more 

 torpid, one cannot help observing that they move with difficulty, 

 and are scarce able to lift their legs, which seem as if glued to the 

 glass ; and by degrees many do actually stick on till they die in 

 the place. 



It has been observed that divers flies, beside their sharp hooked 

 nails, have also skinny palms, or flaps to their feet, whereby they 

 are enabled to stick on the glass and other smooth bodies, and to 

 walk on ceilings with their backs downward, by means of the 

 pressure of the atmosphere on those flaps ; the weight of which 



