196 INJURIOUS AND USEFUL INSECTS 



flies. These are beautiful insects, with long antenna;, slender 

 body, large gauzy wings, and iridescent eyes. Like the lady- 

 bird larva and the Syrphus-larva, the larva of the lacewing 

 preys upon aphids. The eggs are mounted on long, elastic 

 stalks, and fixed among the aphids. The larvse are long- 

 legged, bristly, and narrowed both in front and behind; They 

 spear their helpless prey with the pointed mouth-parts, and suck 

 their juices. One common British species, C. per la, seems to 

 be particularly fond of the rose-aphis. Not only true aphids, 

 but scale-insects and other plant-parasites are devoured by the 

 lacewing larva. Syrphus-larvee in their turn often suck the 

 lacewing larvse instead of the aphids which are their habitual 

 food. Some Chrysopa-larvas have the peculiar habit, not 

 unknown among other insects, of concealing their bodies by 

 fastening around them the skins of their victims. Among the 

 larvae which practise this disguise, for such it probably is, are 

 those of our commonest species, C. perla. 



Before pupation the larva spins a cocoon in a crevice, or in 

 a rolled-up leaf, or between pine-needles, according to the 

 species. Many lacewings, when handled, emit a very dis- 

 agreeable odour, and our common species is one of these. 

 The lady bird larva does the same. 



LEPIDOPTERA 



Structural peculiarities. — The head of the imago is furnished 

 with compound eyes and often with two simple eyes, which are 

 wanting in butterflies. The antennae are often long ; in butter- 

 flies they are clubbed at the tip ; in some moths (Bombycidse, 

 etc.) they exhibit a single or double comb, especially in the 

 male. The mouth-parts found in biting insects become 

 vestigial in a lepidopterous imago, except the maxillae and 

 the labial palps. The maxillae (strictly, the galeae of the 

 maxills) are much prolonged, united by interlocking pro- 

 cesses, and converted into a proboscis, which is usually 

 wound spirally when not in use. The proboscis itself be- 

 comes vestigial in many moths, which do not take food.' 

 The labial palps are relatively large, and stand on each side 

 of the base of the proboscis ; in some families the maxillary 

 palps are well developed. Sometimes all the mouth-parts are 

 reduced to microscopic vestiges {e.g, Hepialus, Psych idae). 



