Guadalupe River Hatch Chart

Guadalupe Insects & Matching Fly Patterns

Unlike traditional trout streams, hatches on the Guadalupe River are generally unpredictable and sporadic. Except for freezing winter days, insects can be found year-round. The following photos were all taken on the Guadalupe River.

Insect	Description	Time of Year	Time of Day	Fly Patterns
Midges
Midge	Size #18-24. Larva and pupa are most important. Common colors are black, olive and brown. Prefer colder water below dam.	All Year	All Day	Larva: Midge Larva, Diamond Midge, Disco Midge, Miracle Midge. G.E.M. Pupa/Emerger: Gray or Olive RS2, Brassie Adult: Griffith Gnat, Adams
Mayflies
Trico Tricorythodes	Size #22-24. Dun has three tails, white wings and black body. Spinner fall occurs right after duns mature. Thick hatches of tricos occur pretty regularly in the morning.	Spring, Summer, Fall	Morning	Nymph: Black Hare's Ear Emerger: RS2, WD40, Foam-Wing Emerger Dun: Not relevant Spinner: Black Poly-Wing Spinner
Blue-Wing Olive Baetis	Size #18-20. Dun has two tails, blue-gray unmarked wings and olive body.	Spring, Summer, Fall	All Day	Nymph: Pheasant Tail, Olive Hare's Ear, WD-40 Emerger: WD40, BWO Foam-Wing Emerger, Sparkle Dun Dun: Blue-Winged Olive, Adams Spinner: Blue Quill Spinner, Poly Wing Spinner
Slate-Wing Drake Isonychia	Size #12-14. Dun has two tails, unmarked wings and four hind legs that are light-colored. Slate-Wing Drakes are becoming more and more common on the Guadalupe.	Spring, Summer, Fall	Afternoon to Evening	Nymph: Pheasant Tail, Mahogany Hare's Ear, Skip Nymph Dark, Zug Bug, Prince Nymph Dun: Mahogany Sparkle Dun, Mahogany Thorax Dun Spinner: Rusty Quill Spinner
Pale Morning Dun Ephemerella	Size #16-18. Dun has three tails, pale olive body, and unmarked wings.			Nymph: Olive Hare's Ear, Prince Nymph Emerger Dun: No-Hackle PMD Spinner: Hen-Wing Rusty Spinner
Hexagenia	Size #8. Dun has two tails, barred wings and yellow body. Hex mayflies are pretty uncommon on the Guadalupe.	Summer		Dun: Not relevant Nymph/Emerger: Chartreuse Woolly Bugger
Light Cahill Stenonema	Size #14. Dun has two tails, barred wings and yellowish-cream body.	Spring, Summer, Fall	Afternoon to Evening	Nymph: Gray Hare's Ear, Prince Nymph Emerger Dun: Light Cahill Spinner
Caddis flies
Caddis (Speckled and Spotted Sedge)	Size #12-16.	Spring, Summer, Fall	Mid-Afternoon to Evening	Larva: Caddis Larva, Peeking Caddis, Brassie, Olive Serendipity Pupa/Emerger: Sparkle Caddis Pupa, Soft Hackle Adult: Elk Hair Caddis, Tent Wing Caddis, Goddard Caddis
Terrestrials
Flying Ant	Size #14-16. Usually happens after a heavy rains in late May and June.	Summer	After rain shower	Foam Ant
Grasshopper	#8-10	Summer	All Day	Dave's Hopper
Others
Egg	Size #12-14. Trout spawn in winter from January to Mid-February.	Winter	All Day	Glo-Bug Egg, Pom-Pom Egg
Scud	Size #14-18. Found more in cooler water upstream near moss.	All Year	All day but mainly in the morning	Shell-Back Scud, Flash-Back Scud
Aquatic Worm Annelid	Size #12-14.	All Year	All Day	San Juan Worm
Minnow	Size #8-12.	All Year	All Day	Woolly Bugger, Clouser Minnow, Zonker, Matt's Bug

Southwest Texas State University Study
According to an April, 1998 study done by Southwest Texas State University:

Scuds+Midges+Mayflies+Caddis flies = 91% of drift.
Mayflies and Midges are most common in the evening drift.
Caddis fly pupae and larvae are most common in mid-afternoon drift Scuds are most common in the early drift, but are available throughout the day.
Blue Wing Olives (#18) and Tricos (#24) are the most common Mayflies.
The Speckled and Spotted Sedge (#12 - #16) are the most common Caddis.
Midges (#18 - #24) are the most common insect in the drift.