AN ENCYCLOPAEDIA OF HORTICULTURE. 



187 



Insects continued. 



Fig. 302), Cockroaches (see Fig. 303), and Earwigs; 

 though some place the last-named Insects in a separate 



FIG. 303. FEMALE COCKROACH. 



order, called Euplexoptera, because of the very neat 

 folding of the hind wings below the front ones. The 

 Orthoptera are destructive during every stage after 

 leaving the egg, and in warm countries they do exces- 

 sive damage at times. In Britain, they cannot be re- 

 garded as of great consequence ; though Cockroaches 

 may gnaw the greenhouse plants, and Earwigs are rather 

 hurtful to florists' flowers, and require to be kept in 

 check (see Cockroaches, Crickets, and Earwig). 

 With the Orthoptera may also be classed the genus 



FIG. 304. THRIPS (magnified). 



Thrips (see Fig. 304) a genus of very small Insects, 

 which live in flowers, and gnaw the surface of the petals 

 (see Thrips). 



Neuroptera are at once far less numerous in species 

 and in individuals, and practically less important than 

 are the orders already discussed. None of the Insects 

 in it can be said to be hurtful to plants. On the other 

 hand, they are frequently of much service, since several 

 of them feed on Insects, and destroy large numbers of 

 injurious kinds. The order is characterised by the 

 possession of four wings, all alike membranous, and 

 supported on a complex network of nervures ; a month 

 fitted for biting. Certain of the sub-orders undergo 

 only an incomplete metamorphosis, while in others the 

 metamorphosis is complete. The larvae are provided 

 with six jointed legs. Neuroptera are mostly carnivorous, 

 alike in the larval state and when mature. Among the 

 better-known forms may be noted Dragon Flies, Heme- 

 robius, and Lacewing Flies. 



Hymenoptera have the wings all membranous and naked, 

 and supported on branching nervures, the hind wings 

 being the smaller ; the wings bear no scales. The month 

 has jaws for biting ; but in some of the sub-divisions of the 

 order, certain parts of the mouth are modified to serve for 

 licking up honey from flowers (in Bees, Wasps, Ac.). They 

 all pass through a complete metamorphosis. The larvae 

 vary much in form, often being like maggots (Bees, &c.), 

 while the Sawflies have larvas not unlike the caterpillars 

 of Moths. Sawflies are very injurious to plants, many 

 of them being hurtful to garden and field produce 

 (Turnip Sawfly, Gooseberry Sawflies, &c.). Some of the 

 Sawflies make true galls on Willows ; and many of the 

 Cynipidce, or Gall-flies (see Figs. 305 and 306), make 

 galls on Oak, Maple, Roses, &c. Most of the Hymenoptera 



Insects continued. 



are of much use in limiting the number of injurious 

 Insects; and among these useful species the Ichneumons 

 hold the first place. In the mature state, none of the 



FIG. 305. GALLS AND INSECTS OF RHODITES Ros*:, showing (1) 

 Entire Bedeguar Gall ; (2) Bedeguar, cut open ; (3) Grub, 

 natural size ; (4) Head of Grub, magnified ; (5) Pupa, magni- 

 fied ; (6) Insect, magnified. 



Hymenoptera can be said to be really injurious to plants ; 

 while many are of great value in conveying pollen from 

 flower to flower. However, Humble Bees are found at 

 times to injure the flowers, by boring through the tube 



Fio. 306. OAK GALL-FLY (magnified). The figure below, and to 

 the right, represents the hinder rings of the Abdomen, and 

 the Ovipositor, which serves to pierce the plant tissues, still 

 more magnified. 



of the corolla to gain readier access to the honey con- 

 tained therein. See also Ants, Galls, Honey, Bee, 

 Humble Bee, Ichneumon Flies, and Sawflies. 



Lepidoptera have the wings usually large (see Figs. 

 307 and 308), membranous, and covered all over with 

 small scales ; the mouth is of no use for biting but 

 has the lower jaws (maxillae) prolonged, so as, when 

 placed together, to form a tube, adapted for sucking 

 honey from flowers. The metamorphosis is complete. 

 The larvae (see Figs. 309 and 310) are of the form known 

 as Caterpillars; and, apart from points of minor im- 

 portance, vary chiefly in the number of sucker feet on 



