CECONOMY OF INSECTS. 39 



witTi great sjTnmetry in rings round the smaller tAvigsof trees; others 

 affix them to the surface of leaves; and again, others lodge them in the 

 crevices of trees. 



The Ephemera, Pfin/ganea, Libellii/a, and Gmt, hover over the water 

 all the day to drop their eggs : these hatch in the water, and continue 

 there while in the larva and pupa form, quittifig the water only when 

 they attain ihe winged state. The mass formed by the eggs of the gnat 

 resembles a little vessel, and floats on the surface. This inject is said to 

 deposit only one egg at a time ; the tirst is retained by means of the legs, 

 Avhen dropped, till a second is depo'-ited next to it, then a third, fourth, and 

 4iirther number, till the mass becomes capable, li-om its synnnetry, to 

 support itself ujiright. ]Many moths cover tiieir eggs with a thick bed 

 of hair or down, collected from their own body ; others cover them with 

 a glutinous substance, which when hard protects them from the ill ef- 

 fects of moisture, rain, and cold. The solitary bees and wasps pre- 

 pare nests in the earth, hollow trees, or cavities in old walls, wherein 

 they place a quantity of food for the support of the young brood when 

 ihey lireak from the egg. The ants are known to construct nests in 

 the earth, in which their eggs are jilacetl with the utmost care. Some 

 deposit their eggs in the larva of other insects, chiefly those of the 

 moth and butterfly kind; and havingpassed through all their changes 

 in their bodies, become what is termed the ichneumon-fly. The 

 Gasteroplulus jE^m^' (bot-fly) deposits its eggs on the bodies of horses in the 

 following remarkable manner. When the female has been impregnated, 

 and the eggs sufliciently mat\ired, she seeks among the horses a sub- 

 ject for her purpose; and approaching him on the wing, she carries her 

 body nearly upright in the air, and her tail, which is lengthened for 

 the purpose, curved inwards and upwards : in this way she approaches 

 the part where she designs to deposit the egg; and suspending herself 

 for a few seconds before it, suddenly darts upon it, and leaves the egg 

 adhering to the hair : she hardly appears to settle, but merely touches 

 the hair with the egg held out on the projected point of the abdomen. 

 The egg is made to adhere by means of a glutinous liquor secreted 

 with it. She then leaves the horse at a small distance and prepares a 

 second egg, and, poising herself before the part, deposits it in the same 

 way. The liquor dries, and the egg becomes firmly glued to the hair : 

 this is repeated by these flies till four or five hundred eggs are sometimes 

 placed on one horse. 



The inside of the knee is the part on which these flies are most fond 

 of depositing their eggs, and next to this on the side and back part of 

 the shoulder, and less frequently on the extreme ends of the mane. 

 But it is a fact worthy of attention, that the fly does not place them 

 promiscuously about the body, but constantly on those parts which are 

 most likely to be licked with the tongue ; and the ova, therefore, are 

 ^hvays scrupulously placed within its reach. 



