The caterpillar is dingy grey or greenish, with a row of black spots down the back, and a whitish stripe on each side. It feeds on the common sorrel (_Rumex acetosa_) and the sheep sorrel (_R. acetosella_), and when fully grown it spins a cocoon on the stem of its food plant, and there changes to a chrysalis. The larva may be found during May and early June. The chrysalis state lasts only a few days, and the moth is on the wing during June and July. _The Broad-bordered Five-spotted Burnet_ (_Zygaena Trifolii_) On Plate IX (fig. 7) will be found a coloured representation of this Burnet. The two crimson spots in the base of the fore wing are very close together, and often touch. The same remark also applies to the two spots on the middle of the wing. A glance at the list of British Moths (Appendix I) will show that we have also a _Narrow_-bordered Five-spotted Burnet. This insect is very similar to the species now under consideration, but may be identified by the narrower purplish margin on the hind wings, and also by the shape of the antennae, which are not thickened so much near the end as they are in _Trifolii_. The larva of the present species is yellowish or greenish, with a row of black spots on the back and a row on each side. It feeds on the bird's-foot trefoil (_Lotus corniculatus_), hop trefoil (_Trifolium procumbens_), and the horse-shoe vetch (_Hippocrepis comosa_) in May. Late in May or in early June the chrysalis may be found in a silken cocoon attached to a stem or leaf; and the perfect insect flies during June and July. _The Six-spotted Burnet_ (_Zygaena Filipendulae_) So common is this moth, and so conspicuous when it flies in the blazing sun, that it must be familiar to almost everybody. On a bright midsummer day hundreds may often be started from their grassy beds from one little patch of ground. [Illustration: FIG. 106.--THE SIX-SPOTTED BURNET.] [Illustration: FIG. 107.--THE LARVA OF FILIPENDULAE.] The colouring of the wings is much the same as in the last species, but there are two crimson spots instead of one near the tips of the fore pair. The larvae may be seen in vast numbers during May and June, feeding on clovers (_Trifolium pratense_ and _T. repens_), and the bird's-foot trefoil (_Lotus corniculatus_); and in the latter month thousands of the chrysalides, inclosed in shuttle-shaped cocoons on grass stems, may be seen on downs and sunny banks in almost every part of the country. The caterpillar, which is yellow, may be known by the two rows of black spots that adorn each segment of the body. CHAPTER XVIII _BOMBYCES_ This tribe is an important one, inasmuch as it contains those few moths whose silk is of present or anticipated commercial value. Many of the British members, even, make silken cocoons of moderate compactness, but none of them yield a quantity and quality of silk to justify any attempt to utilise it in the arts.