| INCHWORM | Caterpillar of a geometer moth (8) |
| PUG | One of a grumble of carlins whose name also means an animal's footprint, a boxer, clay, a fox, an imp, a geometer moth, a monkey or a snub nose (3) |
| TUSSOCK | A dense clump/tuft of grass or rushes to which the caterpillar of a browntail/gypsy moth is likened (7) |
| PRIMROSE | Native British woodland plant with rosettes of yellow or cream petals; county flower of Devon, food of the caterpillars of the rare Duke of Burgundy butterfly (8) |
| RIVULET | A little stream; or, a brown geometer moth with a pale wave on its wings, suggestive of said brook (7) |
| INCHWORMS | Larvae of the geometer moth |
| POLYGONS | Figures that interest geometers |
| PALMER | Word for a pilgrim from the Holy Land carrying a hand-shaped leaf; or, a hairy hoary caterpillar of wandering or migratory habits (6) |
| PUSS | The caterpillar of the ___ moth may squirt formic acid if attacked (4) |
| LARVA | Caterpillar of particular value (5) |
| PERGA | 'The Great Geometer' of ancient times, Apollonius of ___ |
| MOTH | A lepidopteran such as a cream wave, lace border, maiden's blush, purple-bordered gold, small scallop or vestal whose scientific name, Geometridae or geometer, means "earth measurer" (4) |
| EUCLID | Geometer of 300 B.C. |
| RIDER | From the geometer I derived a corollary (5) |
| EUCLIDEAN | Reshaped clue concept new and relevant to one geometer (9) |
| EULER | Swiss geometer |
| PYTHAGORAS | Old geometer too befuddled to graph, say (10) |
| ARCHIMEDES | Greek geometer who reputedly yelled "Eureka!" (10) |
| LOCUS | Geometer's concern |
| QED | Geometer's exultation, e.g. |
