100 



JOURNAL OF HOKTICULTORE AND COTTAGE GARDENER. 



t Fobi-uai-y 4, 1873. 



sects, whicli tisit flowers with a double object — the extraction 

 of the honey and the destruction of other insects, some of 

 which are amongst our enemies. The antennae in these in- 

 Bects are longer than in many flies, the bodies broad, and 

 elegantly marked with spots and streaks of a variety of colours. 

 On the thorax is usually an array of spines, perhaps to pre- 

 vent birds from attacking these insects, which do not appear 

 at all inclined to take up the refrain, "Let me like a soldier 

 fall," but show great alacrity in escaping danger by flight if \ 

 alarmed. The common Chameleon-fly (Stratiomys chamtelio) ' 

 is one of the familiar examples of the group, taking its name '• 

 from the varied colouring displayed by different specimens ; 

 black and yellow, however, predominate, and the legs are also 

 yellow. The 

 larva lives in 

 ponds or stream- 

 lets that have 

 little motion ; it 

 has rather a tele- 

 scopic structure, 

 and respires 

 from orifices in 

 the tail, set about 

 with hairs much 

 in the mode of 

 the larvoi of the 

 gnat. One of the 

 most peculiar 

 circumstances in 

 its history is, 

 that the period 

 of larval growth 

 having passed, 

 the creature rises 

 to the top of the 

 water, where it 

 floats about, the 

 pupa remaining 

 within the loose 

 larva skin, which 

 serves as a kind 

 of cocoon. Other 

 larva? of the fa- 

 mily are semi- 

 aquatic, profer- 

 ring damp places 

 or burrowing in 

 rotten stumps ; 

 the larva of 

 Sargus cuprarius 

 livesin the earth, 

 and those of its 

 congeners. In 

 these insects the 

 bodies are more 

 slender than in 

 the typical repre- 

 sentatives of the 

 family, yet we 

 find brilliant, 

 almost metallic 

 colouring. 



A curious group 

 of flies is that re- 

 presented by the genus Phora, for at certain times of the year 

 parties of these may be seen resting on the glass of window-panes, 

 and if a crowd of them should haunt agreenhouse, as may happen, 

 the gardener is doubtful whether to consider them as neutrals or 

 enemies. It may be that his readiest theory is that they have 

 bred from some manure that he has had on the premises, and 

 some of the larvfe really feed on decomposing substances, vege- 

 table rather than animal, though. Thus, the larva of P. Dauci 

 has been discovered in decaying Radish roots. I don't suppose 

 it would touch healthy ones, and if gardeners leave Radishes to 

 decay in the ground they must not wonder that insects inter- 

 fere. The majority are parasitic, with a history somewhat 

 obscure as yet, though some of the flies have been bred from 

 punctured larvas of Lepidoptcra. Like those of common 

 Muscida>, these larvre are footless cylindrical maggots, slightly 

 narrowed at the head, and with radiating points at the tail, 

 by which they retain their hold. The perfect insects fly, or, 

 one might say skip, about wi(h briskness, the wings being 



deflexed and fringed without transverse veins ; a ridge on the 

 thorax also gives to them the appearance of being hump- 

 backed. Some people have Ukened these flies to sand wasps in 

 miniature, the size varying from the twenty-fourth to the 

 sixth of an inch. We have about thirty British species. Be- 

 sides these, though belonging to the Hymonopterous order, we 

 might place the insects of the family Proctotrupidas, some so 

 small that they only look like moving dots until we magnify 

 them. Here the wings have scarcely any nervures, and the 

 insects spring rather than fly. The larvi-e, so far as is known 

 at present, live in the eggs of other insects, chiefly of moths 

 or butterflies, one small egg serving as food for three or four 

 larvfp ; it is doubtful how the shell is punctured. Teleas 



elatior, one of 

 these, is a beauti- 

 ful object under 

 the microscope, 

 the body being 

 an intense blue, 

 and the winga 

 exhibiting pris- 

 matic tints. 



The Ruby-tail- 

 ed flies are in- 

 sects belonging 

 to the division 

 of Hymeuoptera, 

 called the Tube- 

 bearers (Tubnli- 

 fera), from the 

 segments of the 

 abdomen being 

 formed into a 

 telescopic tube, 

 which, though it 

 seemingly con - 

 sists of a small 

 number of seg- 

 ments, contains 

 the usual com- 

 plement, but mo- 

 dified. It is se- 

 cured by a short 

 footstalk to the 

 thorax. The ob- 

 ject of this struc- 

 ture Mr. Wood 

 thus states, "Ow- 

 ing to the mode 

 in which tlie ab- 

 domen is attach- 

 ed, the insect is 

 able when alarm- 

 ed to roll itself 

 up in a ball. In 

 which it is aided 

 by the shape of 

 the abdomen, the 

 under surface of 

 which is concave 

 so as to receive 

 the thorax. At 

 the end of the 

 retractile tube is 

 a small sting-liie ovipositor, capable of inflict'°g a smart prick 

 when the insect is moved to anger." 



The claim of these flies to beauty must be admitted by every- 

 one who has seen the Chrysididte careering in the sunshine by 

 the roadsides or over flower beds, especially in gardens near 

 woods. Also they may be noticed crawling or running over 

 posts and palings, round orchards and plantations — not with- 

 out an object. England owns nearly a score of species, all of 

 bright colours, green or greenish blue, the abdomen in most 

 of some shade of red or purple. One of our commonest species 

 is CLrysis ignita, the larva' of which are nurtured in the nests 

 of sand-wasps, carpenter and mining bees, and even, according 

 to some authors, in the cells of the hornet. One or two species 

 attack the tunnelling wasps, conveying their eggs with inge- 

 nuity into the cell prepared by the wasp for its progeny. In a 

 certain sense, therefore, the Ruby-tailed flies are of use, by 

 keeping under other Hymenoptera, thoughl of course many of 

 the wild bees do no harm in gardens. Whether, like the 



Fig. 23.— The jietamobphosis op stratiomys i cha ji.elio. 



